UNBiology1a

School Science Lessons
Plant reproduction and growth
2012-01-28 SP
Please send comments to: J.Elfick@uq.edu.au

Table of contents
9.1.0 Angiosperm asexual reproduction
9.3.0 Angiosperm sexual reproduction
9.5.0 Fruits
9.9.0 Plant growth
9.6.0 Seeds

9.1.0 Angiosperm asexual reproduction
9.1.7 Auxins, growth substances
9.1.1 Bulb, daffodil, hyacinth, jonquil, narcissus
9.1.2 Corm, gladiolus, crocus
9.1.3 Lignotuber, banksia, eucalyptus
9.1.4 Rhizome, ginger, iris, Jerusalem artichoke, mint, couch grass, Solomon's seal, bracken fern, canna, tumeric
9.1.5 Runners, strawberry
9.1.6 Stem tuber, potato (Irish potato), starch grains
9.1.8 Tuberous roots, root tuber, carrot, turnip, parsnip, beetroot, sweet potato, dahlia, skeleton weed, dandelion, lesser celandine

9.3.0 Angiosperm sexual reproduction
4.29 Bean flower, (Primary)
9.3.2 Buttercup
9.3.11 Carpels and ovules, buttercup, lily, marsh marigold
9.3.3 Cherry flower
2.31 Collect flowers (Primary)
9.183 Conduction of water in plants, cut flowers in coloured water
9.2.3 Dispersal of seeds and fruits
9.3.18 Fate of flower parts, floral organs
9.3.12 Fertilization, lily
9.3.16 Flower maturity
9.3.1 Flower parts, tomato, lily, chilli
9.2.1 Flower parts, dicotyledons, K, C, A, G, P
9.51 Flowering plants, angiosperms, buttercup, wallflower, groundsel, Phylum Magnoliophyta
9.3.4 Hazel flower
9.2.2 Inflorescences
9.3.6 Lily
9.3.5 Monoecious, dioecious and hermaphrodite plants
6.2.12 Path of the transpiration stream, cut flower stems in ink
9.3.9 Pollen from stamens, lily
9.3.10 Pollen grain and male prothallus
9.3.17 Post-fertilization changes outside the ovule
9.3.15 Post-fertilization developments outside the embryo sac
9.3.14 Post-fertilization fate of the endosperm
9.3.6 Tulip
9.3.7 Willow flower
9.3.13 Zygote development, shepherd's purse

9.5.0 Fruits
9.5.8.1 Achene
9.5.5 Apple
4.30 Bean seeds and pods, (Primary)
9.5.6 Cherry
9.5.0.1 Classification of fruits
9.2.3 Dispersal of seeds and fruits
6.4.13 Dispersal of pine seed by swelling movements
9.5.5.1 Exalbuminous seed, broad bean
9.5.1 Dry indehiscent fruits, achene, caryopsis (grain), samara, cypsela, schizocarp, nut
9.5.2 Dry dehiscent fruits, follicle, legume (pod), lomentum, siliqua (silicula), capsule
9.5.0.1 Fruit classification, dry indehiscent, dry dehiscent, true succulent fruits (fleshy fruits), false succulent fruits
9.5.7 Gooseberry
9.5.12 Legume pod fertilization
9.5.10 Nut
9.5.2.1 Pea pod
9.5.4 Pip fruit, stone fruit and berries
9.5.8 Popcorn, pericarp of maize
9.5.9 Samara
9.5.11 Schizocarp
3.29 Seeds and fruit, (Primary)
1.24 Seeds and seed pods, (Primary)
9.5.3 Succulent fruits (fleshy fruits), berry, drupe, pome, hesperidum, aggregate fruit (syncarp)

9.9.0 Plant growth
6.34a Chemical fertilizers (Primary)
9.9.12 Cotyledon functions
9.9.9 Plant embryo development, shepherd's purse
6.33 Fertilizing soil, (Primary)
9.73 Gravity affects the growth of stems and roots
9.9.4 Growth of first internode, runner bean seedlings
9.9.17 Growth of plants in the classroom without soil
9.9.2 Growth of radicle, zone of elongation, broad bean root
9.9.3 Growth of young shoot, sunflower, castor oil seedlings
4.31 How seedlings grow (Primary)
9.4.1 Mitosis in cells of onion root tip
9.9.13 Natural growth inhibitors
9.9.7 Nodules and galls
2.1.7 Plant growth substances, Safety in school science, ("plant hormones")
9.9.5 Seedlings growing in the light and in the dark, e.g. pea
4.31 How seedlings grow, (Primary)
9.9.14 Zone of elongation of growing root

9.6.0 Seeds
9.5.4.1 Albuminous seed, castor oil plant
9.9.2 Depth of sowing
9.2.3 Dispersal of seeds and fruits
9.5.2 Dry dehiscent fruits, fruit opens to let the seeds out
9.109 Endospermic and non-endospermic seed
9.5.5.1 Exalbuminous seed, broad bean
6.4.2 Geotropism responses in soaked seeds
5.27 Germinate bean seeds
5.29 Germinate maize grain
9.9.1 Germination test
9.5.7.1 Germination of pollen
9.6.0 Germination of seeds
9.9.1 Germination test
9.4.0 Seed-bearing plants, seed plants, Spermatophytes
5.15 Seed germination
21.0 Seeds (Primary)
9.9.0 Seeds (Agriculture)
9.122 Viability of seed before planting

9.1.1 Bulb, daffodil, hyacinth, jonquil,
See diagram 9.81: Bulb of daffodil
1. Cut the bulb of an onion longitudinally through the middle. Note the stem, the outer membranous and inner fleshy scale leaves, and the large central bud containing the rudiments of foliage leaves and the flower. Dissect a bulb and note the presence of buds in the axils of the scale leaves. Cut a bulb transversely and note the arrangement of the scale leaves. Test the fleshy scale leaves for reducing sugars, starch and food reserves with iodine solution. Compare the bulbs. Grow bulbs and investigate the origin of new bulbs.
2. A bulb is an aggregation of fleshy leaf base developed on a short disc-like stem. It is protected by a series of thin, membranous, scale-like leaf bases. The scale leaves are the swollen bases of the vegetative leaves. They are composed of parenchyma cells and are swollen with food stored during the growing season. A longitudinal section shows a terminal bud or growing point, surrounded by the vegetative leaves, with the flowering stem in one of their axils. In daffodil, unlike most bulbs, the flowering shoot is thus lateral to the growing point, is not directly involved in the formation of the shoot, so persists from year to year. The bases of the vegetative leaves swell to form the new fleshy scales, bulb scales, as their organic material passes down to the base. Axillary buds in the axils of the outermost scales may form two daughter bulbs. The innermost scales are the most recently formed, and the outer scales represent the bases of leaves of previous seasons. The stem is flat with many adventitious roots at its base. In onion or hyacinth the growing point produces a flowering shoot with leaves that terminates its growth. Axillary buds arising in the axils of fleshy scales grow at the expense of food synthesized in the green leaves or stored in the bulb scales and enlarge to form the bulbs for the next season. The surface of the bulb is covered by the thin papery exhausted scales of the old bulb. The bulb is a very condensed shoot with extremely short internodes and with leaf bases swollen with stored food.

9.1.2 Corm, gladiolus, crocus
See diagram 9.82: Gladiolus corm
1. A corm is the swollen base of the flowering stem, usually a monocotyledon. Its surface is sheathed in the bases of withered leaves forming membranous brown scales. Remove the scales to see thin depressed scars where axillary buds form. The upper axillary buds form the next season's leaves and flowering shoot. The lower axillary buds can form little corms or "cormlets" (cormels) that can grow into suckers, separate, and reproduce vegetatively. Cut longitudinally through the middle of a corm, passing through one large bud. Test the cut surface of the stem for reducing sugars and starch with iodine solution.
2. The taro corm is an underground stem swollen with stored starch. Like other stems it has these parts: The growing point or a shoot apex. Many leaves joined to the shoot apex. Leaf scars are seen as circular marks that go around the corm. Axillary buds form just above the place where the leaf was joined to the stem. The axillary buds can grow into little corms or "cormlets" (cormels). The cormlets can grow into suckers.
3. The growth of the vegetative leaves and flowering axis uses all the food stored in the old corm but it can be seen below the new corm for some time. The base of the flowering shoot gradually becomes swollen using the food transferred from the leaves, and probably from the old corm also. This basal stem swelling is the young corm, sheathed in the bases of the lower leaves of the flowering shoot. At the close of the flowering period, the leaves and flowering stem wither and their stored food transfers to the swollen stem base while buds are produced in the axils of the withered leaves. See much starch in the outer part of the corm in a vertical section stained with iodine solution. Also, many scattered vascular bundles pass longitudinally to the uppermost buds and others pass laterally into the leaf bases. At the top of the corm are scars left by the withered flowering stem and foliage leaves. The flowering shoot of the next season develops from an upper bud in the axil of a scale leaf. Each new corm is lateral to that of the previous season because it arises as a flowering shoot from a lateral bud in the axil of the uppermost scale loaves.
4. Observe the corm of crocus. In the autumn, note the flattened swollen stem, the adventitious roots, the membranous scales encircling the stem, and the axillary buds. One or more buds near the top of the corm are strongly developed. Cut longitudinally through the middle of a corm and passing through one large bud. Examine the cut surface and note the structure of the bud with its axis, scale leaves, foliage leaves and central flowers. Test the cut surface of the stem with iodine solution. Grow corms and trace the development of the flowering shoot and of the new corms. Note that the old corms of are persistent. Note also that some axillary buds produce widely spreading underground stems that terminate in new corms.

9.1.3 Lignotuber, banksia, eucalyptus
A lignotuber is a swollen region where the trunk and roots meet. It enables the plant to survive fires.

9.1.4 Rhizome, ginger, iris, Jerusalem artichoke, mint, couch grass, Solomon's seal, bracken fern, canna, tumeric
See diagram 9.9.3: Iris rhizome | See diagram 9.83: Ginger rhizome
1. A rhizome is part of a shoot with reduced scale-like leaves. It usually develops horizontally and underground. The apex sends up stems or leaves. The rhizome is composed of a series of segments that have arisen from axillary buds. At the apex of each segment is the apical bud (terminal bud) that forms the large strap-shaped, vertical, sheathing leaves and the flowering axis. The ginger rhizome is hard and compressed sideways. Inside it is pale yellow. It is covered with scales and has fine fibrous roots.
The "stem" of the banana is a false stem (pseudostem). The true stem is an underground stem, a rhizome. The swollen stem base is a corm with very short internodes. The corm makes shoots that grow into branches or other corms. New plants come from these shoots. Suckers grow from the dormant buds, the "eyes" on the corm. Each sucker formed is higher than the corm it came from. When the land is sloping, the suckers are usually formed on the uphill side so generations of banana plants will gradually move up a hill.
2. Development of the flowering axis stops further growth of the segment. Axillary buds just behind form new branches of the rhizome. They also have terminal buds that later form leaves and a flowering axis. Each segment is marked by a series of concentric circles that represent the bases of the former sheathing leaves formed at the nodes. Axillary buds are associated with the circles. Fibrous adventitious roots develop from the under surface of the rhizome. The rhizome can be separated into segments. Each segment can reproduce the plant if it has a growing point. The rhizome is a food storing organ, accumulating much starch. Note the position of the aerial shoots and the way in which more growth of the rhizomes can continue. Note at each node a scale leaf with an axillary bud or branch. Adventitious roots also arise at the nodes. Note how the system becomes progressively more extensive. Note the presence of scale leaves, axillary buds, and adventitious roots.

9.1.5 Runners, strawberry
A runner is a stolon, i.e. a long lateral shoot producing roots at intervals. The shoot between the roots dies to form new individual plants. Plant a well-developed strawberry plant in spring in a dish. Put the dish on a windowsill and water regularly so that the soil does not become either too moist or too dry. Note the runners that grow out of the leaf axils. Note the runners that grow out of the leaf axils. Small leaves appear at their tips. Roots develop which anchor the tip of the runner in the soil and the leaves appear. A new strawberry plan forms. .

9.1.6 Stem tuber, potato
See diagram 9.9.5: Potato tuber with sprouting axillary buds to form aerial shoots | See diagram 9.86: Potato cell with starch grains
1. A stem tuber is the swollen end of an axillary underground branch developed at one of the lower stem nodes from dormant axillary buds called "eyes". Each eye can reproduce the plant. Cut the potato and test the cut surface with iodine solution. Thin layers of cork cells cover the tubers formed from phellogen, cork cambium, layers in which lenticels form. The eyes are within slight depressions with rims on which the scale leaves form, arranged in a distinct spiral. At the apex of the tuber is the terminal bud. At the opposite end is the scar of attachment to the stem that develops the tuber. The tuber is composed of thin walled living and intercellular spaces, and containing large quantities of starch grains of characteristic shape and protein. This stem tuber is different from the root tuber of sweet potato, dahlia, lesser celandine.
2. Scrape a freshly cut surface of a potato tuber with a blunt knife. Transfer some milky fluid on the knife to a drop of water on a slide, then add a coverslip. Find isolated grains under low power then high power. Note the structure of the starch grains. Each grain has a hilum and eccentric stratification.

9.1.7 Auxins, growth substances
Put oat, barley or wheat grains in a flat dish containing tap water. The next day, sow them in a pot. When the seedlings are 3 cm high, cut off 10 mm from the tips of the two thirds of the shoots. Leave one third of the seedlings not treated as a control. Dissolve 1 g of gelatine, with heating, in 20 mL demineralized water. Use this solution to stick back the shoot tips on half the cut seedlings. Note any further growth. The seedlings without a shoot tip stop growing. The seedlings with the shoot tips stuck on again continue to grow almost as much as the control seedlings. The growth substance, auxin, diffuses out of the replaced tips through the gelatine into the cut end, and allow the plant to continue to grow. Under the influence of light, substances form in plants that, in specific concentrations, trigger cell division and cause elongation. These growth substances (auxins) are found especially on buds and root tips.

9.1.8 Tuberous roots, root tuber, carrot, turnip, parsnip, beetroot, sweet potato, dahlia, skeleton weed, dandelion, lesser celandine
See diagram 9.87: Sweet potato tuber
1. In many biennials and perennials the main taproot, and sometimes the chief lateral roots, is very much swollen with stored food. When the aerial organs have died down, they preserve the plant until the next season. In these tuberous roots the new shoot develops at the expense of the reserve foods. Tubers form by secondary thickening of some adventitious secondary roots near the soil surface. As it is a root tuber the sweet potato tuber has are no nodes or internodes or reduced leaves. The end neared the main plant, the "crown" end, may produce shoots, stems and foliage. This end can be cut off and used as planting material. The end furthest from the main plant may produce secondary roots. Examine a sweet potato tuber (tuberous root).
2. The cambium in these tuberous roots forms much xylem parenchyma and few lignified elements. The food surplus is stored in the xylem parenchyma. Weeds with tuberous roots may be broken up during cultivation, develop adventitious shoot buds and propagate the weed. Axillary buds at the base of the foliage leaves also propagate the plant readily. In the dandelion, a peculiar longitudinal contraction of the tuberous taproots wrinkles its surface, and pulls the radical leaves downwards to the soil surface. At times the plant may form a shallow saucer-like pit on the surface of the soil. Similar contractile roots are also developed by crocus, gladiolus, and oxalis. They drag the bulb, corm, or rhizome from which they arise, more deeply into the soil. In gladiolus, each new corm arises on top of the old one and is higher in the soil, but the contractile roots at the base of the corm pull it down to a lower level. Aerial shoots (suckers) also result in vegetative reproduction. They arise from adventitious buds on the roots, and produce new aerial shoots as in begonias, plums, apples, poplars, and many other plants. Some botanists in USA refer to the storage organ of the sweet potato as a root, not a tuberous root, because only the swollen end of an axillary underground branch is a tuber, potato, Irish potato. Note the fibrous, normal roots, and the club-shaped root tubers.
3. Examine plants at various seasons of the year and trace the origin and mode of development of the root tubers.

9.2.1 Flower parts, dicotyledons, K, C, A, G, P
Hibiscus, tomato, lily, chilli, buttercup, larkspur, marsh marigold, shepherd's purse
See diagram 9.98: Parts of a dicotyledon flower | See diagram 9.98.7: Flowers, floral formula
Labels: 1. sepal (all the sepals = calyx, K) 2. petal (all the petals = corolla, C) 3a. anther, 3b. filament (anther + filament = stamen, all the stamens = androecium, A) 4a. stigma, 4b. style, 4c. ovary (stigma + style + ovary = gynoecium or pistil, G) 5. receptacle, 6. flower stalk (pedicel) 7. ovules inside the ovary
A flower grows from the axil of scale leaf or bract and represents a modified shoot. The flower stalk, pedicel, forms a receptacle as a base for the flower parts arranged in concentric whorls or in spirals. Flowers may be hermaphrodite with both stamens and carpels or have only stamens or only carpels. The perianth (P) is usually in two whorls but may be absent. The outer whorl of the perianth, the calyx (K) contains the leaf-like sepals that protect the bud. The inner whorl of the perianth, the corolla (C) contains the petals that are usually showy, coloured and scented to attract insects. The male part, the androecium (A) refers to the stamens that produce pollen and are arranged inside the corolla. The female part, the gynoecium (G) or pistil, refers to the carpels in the centre of the flower. The carpels contain the ovules that form seeds after fertilization. Fruits develop from the carpels, and sometimes other structures. The floral formula shows the number of parts in the calyx (K) corolla (C) androecium (A) and gynoecium (G). Perianth (P) is used when no separate calyx and corolla exist. The symbol oo (infinity) stands for a large and indefinite number of parts. Fusion between parts is shown by brackets round the number, e.g. K(5) = fusion of 5 sepals, K 5 means 5 separate sepals.
Dissect flowers and write the floral formulas. Cut the ovary crosswise and count the ovules or "seed pockets". Look for seeds in the ovules. Rub an anther from a stamen on black paper to see the pollen will usually be seen. Observe the pollen with a microscope.

9.2.2 Inflorescences
See diagram 9.99: Different types of inflorescence
Plants can bear flowers singly or grouped in an inflorescence. Each flower usually has its own stalk, the pedicel. Where the pedicels join the main stalk, the peduncle, is a bract. A spadix is a fleshy spike covered with male and female flowers, e.g. arum lily. Collect plants with different types of inflorescence. Note the peduncle, pedicels, and bracts, and their relative positions.
1. Each flower usually has its own stalk, the pedicel. Where the pedicels join the main stalk, the peduncle, is a bract.
2. A spike is a simple axis with successively younger sessile flowers, so it has no pedicels, e.g. Gladiolus, red clover.
3. A catkin is a unisexual spike without petals that usually hangs down, e.g. mulberry, willow, oak, birch
4. A spadix is a fleshy spike covered with male and female flowers, e.g. arum lily.
5. A raceme is similar to a spike but the flowers have pedicels, e.g. sweet pea.
6. A panicle is an open, repeatedly branched raceme bearing many flowers, e.g. oats and other grasses.
7. A corymb is a raceme with all flowers at one level with the youngest flower in the centre, e.g. apple, rowan, hawthorn.
8. An umbel has flower stalks all arising together at the end of the main stalk, e.g. carrot, parsley, fennel, frangipani, Hydrangea, Lantana.
9. A capitulum, or head, has flowers densely packed on a common receptacle with the youngest at the centre, e.g. sunflower, dandelion, daisy.
10. A cyme has the main axis ending in a flower, the oldest flower, with younger flowers on lateral branches.
11. A spathe is huge bract that can enclose the inflorescence, e.g. coconut.

9.2.3 Dispersal of seeds and fruits
Examine the dispersal mechanisms of seeds and fruits.
1. Dispersal by animals
Birds eat fleshy parts of blackberry or cherry drupes but not the hard seeds protected by a hard endocarp. Birds are irritated by the sticky receptacle of mistletoe fruit so it wipes the fruit on branches. Animals carry hooked fruits, burs, in their coats, e.g. capitulum of common burdock covered by spiny bracts. The weed cobbler's pegs has toothed bristles that attach the fruit to your socks.
2. Dispersal by wind
Dandelion, thistle and other Compositae have a ring of white hairs, pappus, to form a parachute and carry the achene. Seeds of willow have tufted hairs. Poppy has a pepper-pot mechanism to shake out tiny seeds from its capsule. Similarly Eucalyptus and Leptospermum have a capsule that opens by slits. The fruit of the castor bean, Ricinus, suddenly split apart to throw out seeds. Clematis and wood avens (Geum urbanum, herb bennet) have plumed fruit. The elm tree and the ash tree have winged fruit. Orchids have extremely light seeds. Spinifex and various "tumble weeds" produce a ball-like cluster of fruits to be bowled along by the wind
3. Dispersal by water
Waterlily seeds and fruit can float. Also, coconut fruits can float but they may not be viable after some time.
4. Mechanical dispersal
The drying pods of peas, beans, Wistaria and other legumes twist to send out seeds like a catapult. Geranium has a splitting schizocarp. The squirting cucumber squirts out its seeds.

9.3.1 Flower parts, tomato, lily, chilli
See diagram 9.4.2: Tomato flower and fruit | See diagram 9.98.1: Lily flower | See diagram 54: Chilli flower

9.3.2 Buttercup
Note the number, arrangement, shape and colour of each set of organs, viz. sepals, petals, stamens and carpels then dissect the flower. Note that the sepals are pale green, boat-shaped, and covered, on the outside with hairs. The petals are yellow, larger than the sepals, heart shaped, and each bears a nectary at its base. Each stamen is divided into two main portions, the filament and the anther head, whereas the carpels are free and each is composed of an ovary, a style and a stigma. Half a flower should then be drawn. This shows the relative positions of the various organs of each whorl as they are set upon the receptacle. This should be followed by a true longitudinal section, which shows only those organs through which the scalpel passes when cutting the flower longitudinally. A floral diagram should then be drawn, and the whole study completed with a floral formula.

9.3.3 Cherry flower
1. The cherry flower has male and female flowering parts in one flower. On the outside are the sepals, then the petals, then the male parts, the stamens, and in the middle of the flower is the female part, the pistil. A flower that contains both female and male parts is called a hermaphrodite. Hold a cherry flower by the stem and detach all the individual parts with tweezers. Begin with the outer parts of the flower and work inwards. Finally, cut off the part of the stem in the middle of the flower. Put similar parts in groups and arrange the groups on the table in the order in which you detached the parts from the flower. The first group are the sepals. They form the calyx that protects the bud before blossoming. Note their colour, shape and number. The second group are the petals. They form the corolla, protecting the inner parts of the flower and attract insects. Note their colour, shape and number. The third group are the stamens. Note their colour, shape and number. Use a magnifying glass to see a thin stalk, the filament, with an anther on top that contains the pollen. The last part cut away from the stem is the pistil. The pistil has of three sections. The convex lower section, adjoining the stem, is the ovary, which merges into the style at the upper end. The tip of the style is called the stigma.
2. Study a cherry blossom with the naked eye and then under a magnifier.
Note the following:
1. The small, green, outer leaves, called the sepals that form the calyx, which protects the flower bud before it opens.
2. The white petals that form the corolla protect the inner parts of the flower and attract insects.
3. The stamens, on and above the petals. Each stamen consists of a small thin stalk, the filament, on which the anther is mounted. The stamens are the male parts of the flower. The anthers contain the pollen.
4. The pistil is in the centre of the flower.
It consists of three sections:
4.1 The bulbous, lower section, which adjoins the stalk of the flower, called the ovary.
4.2 The style is attached to the upper end of the ovary.
4.3 The upper end of the style forms the stigma. The pistil is the female part of the flower.
5. To observe how the various parts of the flower are arranged and are related to each other, separate all the parts of the flower at their points of attachment. Use forceps, starting at the outside. Put similar parts together on a black piece of cardboard. Write the names next to the rows of the various parts of the flower. Study other flowers in the same way, e.g. columbine, primrose, dog rose, snapdragon and apple blossom.

9.5.6 Cherry seed
The cherry has a seed with a very hard shell in the middle of the fruit called the stone. The plum, apricot and peach are also stone fruit. The name "cherry pip" is also used colloquially, but is not technically correct. The stone of the stone fruits, like the core of the pip fruits, is surrounded by fruit pulp enclosed in a skin.

9.3.4 Hazel flower
The hazel flower is either male or female. The male flowers are grouped in catkins, and the female flowers are in the buds with the clusters of red threads. The two types of hazel flower are found on different parts of the same bush. In the spring find a hazel bush twig with catkins which are already flexible and loose. Hold the twig over a hard dark surface and hit the catkins with a glass rod. The yellow dust which falls is pollen, so the catkins are male flowers. The male parts of a flower are the stamens with filaments and anthers. The female part is the pistil with ovary, style and stigma. To see whether the male and the female parts are in hazel catkins use a magnifier to examine the most wide open catkin. On the flexible stem of the catkin are very many small leaf-like scales. They stand out from the stem of the catkin like small rooftops. As well as the catkins there are also buds on the twigs of the hazel bush with a bundle of fine red thread on their tips. Use tweezers and a dissecting needle to remove the small leaves and the scales which enclose the bud. Inside there are several green scale-like small leaves. To one side on the lower edge there are two small egg-shaped structures, the ovaries. The style and stigma of these ovaries are divided and are the red threads which jut out from the bud.

9.3.5 Monoecious, dioecious and hermaphrodite plants
Male and female gametes may be on the same flower or on different flowers.
Hermaphrodite, bisexual, perfect flowers have male and female organs. Complete flowers have male and female organs and petals and sepals.
Monoecious plants have separate male and female flowers on the same plant, e.g. maize Zea mays
Dioecious plants have separate male and female flowers on separate plants, so they have male plants and female plants, e.g. holly, ginkgo, persimmon

9.3.6 Tulip, lily
Examine specimens of large simple flowers, tulip or lily. Count the stamens and observe how they are arranged about the central pistil. Make large diagrams of the essential organs. Label the parts of the pistil (stigma, style and ovary). Label the parts of the stamen (filament and anther). The end of the stalk on which the flower grows is called the receptacle. At the base of the receptacle there are usually leaf-like structures that enclose the bud. These are called sepals. Above the sepals there is usually a ring of brightly coloured petals called the corolla.

9.3.7 Willow flower
Collect willow branches with catkins beginning to open. Willows have two types of catkins, oval-shaped or round and, pale to bright golden yellow and oblong, cylindrical and a greenish colour. Note whether both types of catkin occur on one branch or on the same tree. Study an oval-shaped catkin by cutting longitudinally with a razor blade and using a magnifying glass. It contains many stamens which sit in pairs on a hairy leaf scale (bract). They form the male (or pollen) flower. Study an oblong, greenish catkin by cutting longitudinally with a razor blade and using a magnifying glass. Observe the many bottle-shaped greenish structures, the pistils (the female flower organs). Each pistil sits on a hairy leaf scale (bract). In the hazel tree male and female flowers are separate but on the same bush. Sex differentiated plants on which both male and female flowers are found on the same plant are called monoecious, sex differentiated plants in which the male and female flowers are found in different plants are called dioecious plants. Some dioecious plants possess fruits which can be eaten, e.g. sea buckthorn. Its fruits are very rich in vitamin c and give a pleasant tasting juice.
When a plant flowers differs between species. Anemones, primroses, cherry trees and apple trees flower in spring. Larkspurs, roses and carnations flower in summer. Dahlias and chrysanthemums flower in autumn. Christmas rose flowers in winter.

9.3.9 Pollen from stamens, lily
See diagram 9.98.2: lily stamen
The stamens are attached to the receptacle inside the corolla and outside the carpels. Each stamen consists of a filament like a little stem and terminal anther that produces pollen. The anther has of four sporangia, each occupying a lobe. The sporangia are held together by parenchyma tissue with a small vascular bundle called the connective. An adnate anther is fused to the filament, Ranunculus. A versatile anther swings loosely at the end of the filament, lily. Most anthers open by a longitudinal slit down each side so that the pollen from the two contiguous sporangia is shed simultaneously. Some anthers shed pollen by terminal pores. A transverse section of a young anther shows four locules or sporangia, two on each side of the connective with its vascular bundle. Each sporangium has an epidermal layer of cells with a thin cuticle, a fibrous layer of cells, parenchyma cells, and a tapetum, composed of a single layer of cells with large nuclei and dense contents and projecting into the sporangium. The tapetum nourishes the pollen-mother-cells (spore-mother-cells) inside that have thick walls, dense cytoplasm, and a large nucleus. As the anther matures, each diploid pollen-mother-cell divides by meiosis to form four haploid pollen grains. The walls of the pollen-mother-cells breakdown to release the pollen grains. Dehiscence occurs between the two contiguous sporangia where the cells have thin walls and readily split apart under tension when the cells of the fibrous layer contract. The split extends down each side of the anther to liberate the dry pollen grains.
Cut sections of anthers Place the anthers of a lily flower, or other large anthers, in alcohol for about a week. Cut transverse sections, mounting in glycerine, and note the structure as described in the text. Also, buds of marsh marigold also harden alcohol and may be sectioned at the level of the anthers.

9.3.10 Pollen grain and male prothallus
See diagram 9.98.3: lily pollen grain
Each pollen grain contains a small generative cell and a large tube cell. Pollen grains shed from the anthers are carried by wind or by insects to a stigma, the receptive part of the gynoecium. Germination of the pollen is induced by the secretion from the stigma. The large tube cell divides to form the pollen tube that grows through pores in the wall of the pollen grain then grows down through the style tissue to reach the ovary. The small generative cell divides to form two male cells that function as gametes and may seem naked nuclei. As the pollen tube emerges from the pollen grain, the tube nucleus passes to the tip of the pollen tube leaving behind the two male cells. The pollen tube and its two small cells represent the male prothallus found in more primitive plant forms, liverworts, mosses, ferns and conifers. The germination of pollen grains can be studied using different concentrations of sugar solutions.
Observe the germination of pollen grains. Put fresh pollen in a 10% sugar solution for 12 hours and examine them with a magnifying glass. You may find germinating pollen on the stigma of a flower. Observe pollen stained with methylene blue under low power. Observe the germination of pollen in the styles of chickweed, taken from a flower which is just beginning to fade. Mount the styles in a dilute aqueous solution of methylene blue.

9.3.11 Carpels and ovules, buttercup, lily, marsh marigold
See diagram 9.98.4: Lily gynoecium | See diagram 9.98.5: Lily ovule | See diagram 5.4.2: Tomato flower and fruit
1. The carpels appear in the centre of the flower, and usually end the growth of the floral axis. Together the carpels form the gynoecium or pistil. An apocarpous gynoecium has separate carpels, Ranunculus. A syncarpous gynoecium has fused carpels. Lily 3 fused carpels. The gynoecium of legumes is a single carpel.
2. Each carpel consists of three parts:
2.1 The ovary at the base contains the ovules.
2.2 The style is an extension of the ovary.
2.3 The stigma at the end of the style secretes a sticky, sugary fluid to catch the pollen grains.
2.4 The ovule consists of a mass of cells, called the nucellus or megasporangium, surrounded by two rings of tissue called integuments.
3. The nucellus develops the diploid megaspore-mother-cell that divides by meiosis to form four haploid megaspores, while the megaspore-mother-cell becomes a large oval cell called the embryo sac. Of the four megaspores in a row in the embryo sac only the megaspore nearest the food supply and farthest from the micropyle survives because it crushes and absorbs its three sister megaspores. The surviving megaspore divides by three mitosis divisions to form the eight nuclei of the embryo sac (2 synergids, 1 ovum, 3 antipodals, 2 polar nuclei). At the micropyle end of the embryo sac are three nuclei or cells surrounded by cytoplasm with thin membranes. Two of these cells are pear shaped and called the synergids. The third cell is the globular ovum. At the other end of the embryo sac are three cells called the antipodals. In the centre of the embryo sac is the large fusion nucleus formed by the fusion of two polar nuclei. The embryo sac that represents the female prothallus is still surrounded by cells of the nucellus.
4. Placentation refers to how the ovules are attached to placentas in the ovary.
4.1 Parietal placentation is where the ovules are attached to the wall of the ovary, poppy.
4.2 Axile placentation is where the ovules are attached to the central axis of a multilocular ovary, lily.
4.3 Free central placentation is where the ovules are attached to the axis but the ovary is unilocular, primula.
5. The stigma is hollow or contains loose mucilage secreting cells to help the pollen tubes reach the ovarian cavity.
6. The pollen tube probably absorbs nutrients from this style tissue in flowers with long styles.
7. Cut sections of ovules. Take a just opened flower of marsh marigold and remove the sepals and petals. Harden the group of carpels in alcohol and then cut transverse sections of these. Cut a large number of sections and pick out a few thin ones which have traversed an ovule and mount in glycerine. These will give longitudinal sections of the ovules which can be compared with the figures in the text. Transverse sections of syncarpous ovaries should also be cut, tulip and lily.

9.3.12 Fertilization, lily
See diagram 9.98.6: Lily fertilization
The end of the pollen tube in the cavity of the ovary, enters the micropyle, penetrates the nucellus tissue, enters the embryo sac and bursts to set free its two male gamete cells. One male gamete unites with the ovum to form the zygote, the essential act of fertilization. The other male gamete cell unites with the fusion nucleus to form the primary endosperm nucleus or triple fusion nucleus. The synergids and antipodals shrivel and die. In angiosperms the endosperm develops only after fertilization. The triple fusion nucleus divides to form thin walled parenchyma tissue that accumulates food reserves, starch, oil and protein. As the endosperm develops, it crushes the nucellus.

9.3.13 Zygote development, shepherd's purse
See diagram 9.99.1: Shepherd's purse embryo 1 | See diagram 9.99.2: Shepherd's purse embryo 2
The zygote forms a firm cellulose wall then divides transversely into a filament of three cells called the pro-embryo. The large cell nearest the wall of the embryo sac is the basal cell that attaches the embryo to the wall. The middle cell is the suspensor initial that divides transversely to form a short filament called the suspensor. The uppermost cell is the embryonic cell. As it is towards the centre of the endosperm, it is nearer its food supply and can divide frequently to form the greater part of the embryo. The embryonic cell divides by a transverse wall and then by two longitudinal walls at right angles to each other, to form the octants. Each octant then divides by walls parallel to the surface (periclinal) into an outer and inner cell. The superficial layer later divides only by walls at right angles to the surface (anticlinal) and forms the dermatogen, which produces the epidermis. The inner cells divide periclinally, so that inner and outer series of cells are formed. In the lower part of the embryo, this segmentation is much more regular than in the upper half the lower forms the hypocotyl and root, while the upper forms the cotyledons (seed leaves) and plumule (terminal bud). The central cells are the plerome, which produces the stele tissues, while the outer series is the periblem and produces the cortex. The uppermost cell of the suspensor is the hypophysis, which forms the root apex by division. Between the two cotyledons the small plumule arises at the base of the groove between them and terminates the hypocotyl. The hypocotyl and radicle with its root cap, have all developed from the embryo initial and the hypophysis of the pro-embryo. The greater part of the embryo, however, arises from the embryo initial. In monocotyledons a pro-embryo of three primary cells is formed as in dicotyledons. However only one cotyledon appears terminal on the hypocotyl, while the plumule arises laterally.
Examine stages in the development of the embryo of shepherd's purse A flowering shoot, freshly gathered, with a few flowers at the top of the raceme and a succession of fruits below will provide the necessary material. Remove ovules from a fruit which has attained a size about one third of that of a mature fruit. Place these in a drop of 1% caustic potash until they become transparent, cover and examine the general form of the campylotropous ovule. Then press gently on the coverslip. This should cause the embryos to escape from some of the ovules. Now irrigate with dilute acetic acid, a treatment which renders the embryo walls more apparent. Embryos squeezed out from the ovules of both older and younger fruits should be examined in the same way

9.3.14 Post-fertilization fate of the endosperm
See diagram 9.99.3: shepherd's purse embryo
As the embryo develops it occupies a groove in the centre of the endosperm. In exalbuminous or non-endospermic seeds, legumes, the embryo absorbs the endosperm and food reserves are transferred to the large fleshy cotyledons. In albuminous or endospermic seeds the embryo remains surrounded by the endosperm.

9.3.15 Post-fertilization developments outside the embryo sac
In most angiosperms, the nucellus is exhausted by the development of the ovule. In ripe seeds, it may be present as a thin membrane between the endosperm and the seed coats. The integuments of the ovule form the permanent seed coats that are thin and membranous in some species hard and woody in others. When the funicle attaching the seed to the placenta dies, the seed is separated from the ovule and is ready for dispersal. When the seed is shed from the plant, it may not germinate because it requires a period of dormancy.

9.3.16 Flower maturity
Collect specimens of flowers in different stages of maturity, from newly opened buds to specimens in which the petals have fallen. Cut each ovary open, and note the changes that take place during seed development. Roses, apples and tomatoes are good for this purpose.

9.5.1 Dry indehiscent fruits, achene, caryopsis (grain), samara, cypsela, schizocarp, nut
See diagram 9.4.2: Pollination, fertilization, fruit formation | See diagram 9.100.1: Pollination | See diagram 9.100.2: Fertilization
1. Dry indehiscent fruits, fruit does not open to let the seeds out
1.1 Achene: One carpel, one seed attached to hard pericarp, e.g. buttercup, strawberry, rose, cashew, sunflower.
1.2 Caryopsis or grain: Usually has one carpel, ovary wall, pericarp and seed coat, testa, fused together, e.g. cereals, grasses, wheat, maize, rice.
1.3 Samara: Pericarp that forms wings, e.g. maple, sycamore, ash.
1.4 Cypsela: Two carpels, like an achene but it has an inferior ovary (buried in the receptacle), e.g. dandelion, sunflower, daisy.
1.5 Schizocarp: Carpels fused together to form an ovary that splits when ripe, e.g. geranium, mallow, hollyhock.
1.6 Nut: More than 1 carpel and a woody wall, e.g. macadamia nut, hazel nut (a peanut is not a nut!).

9.5.2 Dry dehiscent fruits, follicle, legume (pod), lomentum, siliqua (silicula), capsule
The fruit opens to let the seeds out.
See diagram 9.72.1: Legume | See diagram 9.72.2: Legume flower | See diagram 9.100.8: Siliqua, silicula, follicle
2.1 A follicle has one carpel and it dehisces (splits) along one margin only, e.g. oleander, Grevillea, larkspur, columbine.
2.2 A legume, pod, has one carpel and it dehisces (splits) along both margins, e.g. legumes, pea, bean, lentil, acacia, peanut (groundnut) cowpea, tamarind.
2.3 A lomentum has one carpel and the pod is constricted between seeds so it breaks into one seed pieces, e.g. clover, Cassia, bird's foot trefoil.
2.4 A siliqua (silique) has two united carpels, e.g. shepherd's purse, stock, cabbage.
2.5 A capsule has three or more carpels and it opens by pores or splits, e.g. Eucalyptus, Leptospermum, poppy, lily, pansy, violet, iris, snapdragon, cotton, castor oil, kapok, okra, rosella.
1. The follicle of larkspur splits along its ventral suture. It is formed from one carpel and contains several seeds.
2. A pod is a dry dehiscent fruit with many seeds. The legume, pea, develops from a single carpel and splits along both margins. When the pea fruit is ripe, both parts of the pericarp twist to throw the seeds some distance from the parent plant.
3. Examine different types of siliqua and silicule, e.g. wallflower, shepherd's purse, honesty. These fruits are formed from two fused carpels, and are distinguished by the formation of a false septum. Note how they split to expose the seeds.

9.5.2.1 Pea pod
See diagram 9.100.4: Drupe, mango, coconut, legume (pod)
When squeezing open a pea pod, you find the many seeds, the peas, lying in a hollow space. This is also the case with bean pods. You call such a fruit pod a "fruit". In legumes the seeds, peas or beans, are suspended in a pod. With the bean plant, you eat either the entire fruit (green beans as soup, a vegetable or salad) or only the seeds (e.g. bean soup made from white, dried beans). With the pea, you eat only the seeds in pea soup, green peas as a vegetable or peas pudding. Some peas can be eaten whole including the pea pod and enclosed seeds. In France these peas are called "mange tous" (eat all) peas.

9.5.3 Succulent fruits, "true" succulent fruits, fleshy fruits, berry, drupe, pome, hesperidum, aggregate fruit (syncarp)
See diagram 9.100.3: Succulent fruits | See diagram 9.100.10: Strawberry, rosehip | See diagram 1.4: Screwpine
See diagram 9.100.3: Berry, pineapple, banana | See diagram 9.100.4: Drupe, mango, coconut, pea | See diagram 9.100.5: Pome (apple)
See diagram 54: Chillies | See diagram 5.6.3: Banana | See diagram 55: Cocoa | See diagram 53: Coconut
The succulent part of a "true fruit" is formed from the ovary wall
Note the complete fruit and longitudinal and transverse sections, berry (gooseberry, currant, chillies, tomato, banana, grape, orange) pepo (cucumber) drupe (plum, cherry, coconut, cocoa walnut) pome (apple, pear) aggregate fruits (blackberry, raspberry, pineapple, custard apple, rose hip, Pandanus).
1. A berry has more than two carpels and the pericarp is divided into 1. skin, epicarp, 2. fleshy or fibrous mesocarp, 3. thin skin, endocarp, e.g. chillies, tomato, capsicum, eggplant, banana, gooseberry, date, currant, grape, avocado, papaya, passionfruit, allspice pimento, pomegranate, guava, mangosteen, carambola (star fruit) pumpkin, melon, cucumber, marrow, squash, snake gourd, gooseberry, currant, chilli, tomato, banana, grape.
2 A drupe has one carpel above the receptacle. The pericarp is the outer skin, epicarp. The mesocarp is fleshy or fibrous. The endocarp is hard and stony. It encloses one seed, kernel, e.g. "stone fruit": cherry, peach, apricot, plum, almond, cocoa, coconut, mango, cashew, coffee, pepper, nutmeg (walnut 2 carpels)
Succulent fruits, "false" succulent fruits
The succulent part of a "false" fruit is not formed from the ovary wall, e.g. fleshy receptacle of an apple or fleshy axis of a pineapple.
3.3 A pome has a "core", the ovary, and a fleshy receptacle, e.g. apple, pear, quince. You can bite into the fleshy receptacle of a ripe apple.
3.4 A hesperidum has many fused carpels, with pulp and tough rind containing oil glands, e.g. citrus, orange, grapefruit, lemon, lime.
3.5 An aggregate fruit, syncarp, is a collection of several carpels from one flower, e.g. blackberry, breadfruit, custard apple, fig (a syconium) jack fruit, mulberry, Pandanas, pineapple, raspberry, rose hip (achenes) strawberry (achenes).
Collect different fruit, slice each fruit transversely and longitudinally, and determine the type of fruit.

9.5.4 Pip fruit, stone fruit and berries
See diagram 9.100.3: Berry, pineapple, banana
Distinguish between:
4.1 the seeds that differ in size and number,
4.2 the fruit pulp which can be juicy,
4.3 the peel or skin that has different thicknesses and may contain oil glands.
4.4 You eat the fruit pulp and the skin of pip and stone fruits, but, not as a rule, the seeds. With the berries, you usually eat the whole fruit.
Allocate fruits to these groups and note which parts of which fruits can be used for food. Cut the fruits in half lengthways.

9.5.4.1 Albuminous seed, castor oil plant
See diagram 9.103: Castor plant
Note the embryo, with its hypocotyl, radicle and plumule. The cotyledons are thin and tissue-like. The seed is albuminous. Note the testa surrounding the seed. Test the food reserves present in the seeds.

9.5.5 Apple
See diagram 9.100.5: Pome, apple
The apple has a core in the middle of the fruit containing pips, the seed of the apple tree. So the apple is a pip fruit. The pear and quince are other examples of pip fruits but the core is surrounded by the mesocarp or fruit pulp enclosed by the peel.

9.5.5.1 Exalbuminous seed, broad bean
See diagram 9.110.1: Broad bean
1. Soak the seed for twenty four hours before dissecting. Note the embryo, with its hypocotyl, radicle and plumule. The cotyledons are thick and fleshy. The seed is exalbuminous. Note the testa surrounding the seed. Test the food reserves present in the seeds.
2. Examine the soaked seed. Note the hilum, elongated brown scar, at one end of the seed. At this point the seed was attached by a stalk to the inside of the fruit.
3. Remove the testa, seed coat, to reveal the embryo. The embryo consists of two large fleshy cotyledons attached to a small axis. The tips of the axis are the radicle, embryo root, and plumule, embryo shoot. The radicle can be seen at one side where it was inserted into a pocket in the testa. Remove one cotyledon to reveal the plumule. Apply some dilute iodine solution to a broken surface of the cotyledon and note the positive reaction to the starch test.

9.5.7 Gooseberry
A gooseberry has many pips distributed in the fruit pulp and not enclosed in a core as with the pip fruits. Fruits of this kind are called berries. You talk of the gooseberry, the raspberry and the strawberry, which are similarly rightly included among the berries. The fruit pulp of the berries is also surrounded by peel or skin.

9.5.7.1 Germination of pollen
See diagram 9.123: Germinating pollen grain
Make a strong sugar solution and put it in a shallow dish like a saucer. Shake pollen from several kinds of flowers on to the surface of the sugar solution. Cover with a sheet of glass and let it stand in a warm place for several hours. Observe little tubes growing from the pollen grains. Use a magnifying glass.

9.5.8 Popcorn, pericarp of maize
Heat 3 tablespoons (45 mL) of high smoke point oil, e.g. canola, peanut or grapeseed oil, vegetable oil in a 3-quart saucepan on a medium high heat stove until it is very hot but not smoking. Add three or four popcorn kernels to the oil and cover the saucepan. If they pop then the oil is hot enough so you can add the 1/3 of a cup of popcorn kernels and immediately close the lid, remove the saucepan from the heated stove and wait for 30 seconds to bring all the kernels to a ready to pop temperature. Return the saucepan to the heated stove. The kennels immediately start popping. Shake the saucepan to avoid burning the kernels and move the lid slightly to allow steam to escape. When the popping almost ceases dump the popcorn into a bowl. As the kernel gets hotter, water inside the pericarp vaporizes to turn the starch into a hot gelatinous mass. With increased internal pressure, the kernel explodes with a popping noise and the starch solidifies intro a fluffy white mass as it leaves the pericarp shell. Examine any kernels that have not popped. They usually are very small or have an unusual shape that interferes with the breaking of the pericarp. The pericarp of popcorn kernels is four times stronger than regular maize kernels

9.5.8.1 Achene
See diagram 9.100.10: Achene, strawberry
Use a magnifying glass to examine the collection of carpels of the buttercup, when they have ripened after fertilization, thus forming a collection of fruit. Each fruit is an achene. Dissect one and find the single seed enclosed. Compare and contrast a ripe strawberry with the collection of buttercup fruits.

9.5.9 Samara
Examine a bunch of ash fruits. Make a detailed examination of a single fruit and cut a longitudinal section of it, thus exposing the seed. Examine a double samara of the sycamore.

9.5.10 Nut
Examine a hazel nut, partly enclosed in its leafy cup. Examine the nut in detail and expose the seed. Compare this fruit with that of the buttercup. (Note: A "peanut" is not a nut.)

9.5.11 Schizocarp
Examine the schizocarp of the hollyhock, and compare this with the other types of dry, indehiscent fruits.

9.5.12 Legume pod fertilization
Examine about 1 kg of fresh-picked legumes, e.g. peas or string beans or other legumes. Pick out the pods that are not completely filled. Open these and compare them with fully filled specimens. The abortive seeds are the remains of ovules that were not fertilized by pollen.

9.9.2 Growth of radicle, zone of elongation, broad bean root
See diagram 5.6.1: Growth of bean root | See diagram 9.102: Growth of broad bean radicle
The increase in root length results from growth in the zone of elongation between the root tip and where the root hairs begin. Germinate a broad bean seed. When its radicle is 2 cm long, mark with Indian ink from the tip upwards at intervals of exactly a millimetre, for about 10 mm. Use a wide-necked jar with a cork lid and half full of water. Push a long pin through the cork and the seed to suspend the seedling in the jar with the root in the water. Wrap aluminium foil around the jar to keep the root in the dark. The next day, note how the ink marks have moved apart because of the growth of the root. The ink marks have moved different distances apart. The marks near the root tip have not parted much. The marks further away have parted further but the top marks and may not have parted at all.

9.9.3 Growth of young shoot, sunflower, castor oil seedlings
See diagram 9.0: Castor seedling
Do a similar experiment with a young shoot. Grow the seedlings on damp sawdust or potting mix.

9.9.4 Grow of first internode, runner bean seedlings
See diagram 9.129.1: Growth-measuring apparatus
When they are sufficiently developed, take daily measurements of the increase in length of the first internode. Record these measurements for 2 weeks then plot the data on a graph.

9.9.5 Seedlings growing in the light and in the dark, e.g. pea
Soak same-size seeds, e.g. pea or bean, in water and sow in same-size flowerpots. Put one pot in a well light place and the other pot in the dark. After the seedlings in the light grow to a height of 3 centimetres, compare the seedlings grown in the light and in the dark. Remove the plants from the pots, wash and dry them and weigh them. The etiolated plants grown in the dark are taller but their dry weight per plant is less than the plants grown in the light.

9.9.7 Nodules and galls
These are the result of growth stimulation by various agents: bacteria, viruses and insects. They may be beneficial, as are the root nodules caused by Rhizobium, a bacterium that fixes nitrogen when inside the root where a symbiotic association occurs. Some types are formed by parasitic associations, e.g. insect galls, or are pathological, e.g. sunflower gall and virus infections. Plants respond to the presence of the bacteria by producing auxins and kinins that are responsible for the abnormal cell division that lead to the swelling. Use young sunflower plants, half of which, about a week ago, received an inoculation of bacteria, Agrobacterium tumefaciens, which cause galls. Note normal growth and deformity caused by the bacteria.

9.9.9 Plant embryo development, shepherd's purse
See diagram 9.99.1 | See diagram 9.99.2 | See diagram 9.99.3
1. As there are often considerable differences in the time for development between embryos of the same age, grow many more than you need for the experiment. Put the seeds in a flat glass dish, add water, and allow the seeds to swell. For embryos in an early stage of development, put the swollen seeds in a flat glass dish on moist absorbent paper and leave until the desired stage has been reached. For seedlings of a greater, put the swollen seeds in a flowerpot filled with sawdust or sand. Stand the pot in one half of a flat glass dish and water regularly. For erect seedlings, rotate the flowerpot occasionally so that all seedlings get an equivalent amount of light, or use a clinostat. When the plants have reached the desired stage of growth, remove them from the sawdust and rinse under water.
2. The plant embryo develops from the fertilized ovule of the egg cell as the result of numerous cell divisions. During this process it passes through various stages of development, from the scarcely differentiated state with a small number of cells to the form where the cotyledons and the roots are clearly distinguishable. Investigate the development of embryos of shepherd's purse. Use forceps and a dissecting needle to open carpels of shepherd's purse taken at different ages and remove several ovules. Put a drop of 5% potassium hydroxide solution on a slide using a glass rod, put the ovules in the drop and put a cover slipover them. The tissue of the ovules is disintegrated, disaggregated, to some extent by the potassium hydroxide. Press down on the cover slip with the handle of the dissecting needle to squeeze the embryos out of the ovules. Do this operation with the utmost care to avoid crushing the embryos. Press down several times and check through the microscope after each application of pressure. Examine the preparation under 50 x, objective 10 x, eyepiece 5 x, and then under 200 x, objective 40 x, eyepiece 5 x, microscopic magnification. If, by luck, ovules of differing ages were transferred to the slide, embryos in almost all stages of development will be present. Draw embryos in different stages of development and arrange them according to age.

9.9.12 Cotyledon functions
See diagram 9.103: Castor plant
Place six similar bean seedlings on which sprouting primary leaves are just emerging, in test-tubes so that the roots are immersed completely in water. Hold the seedlings in place with cotton wool plugs, but the water must not contact the cotton wool. Keep two seedlings with both cotyledons. Remove one cotyledon from each of two other seedlings, and remove both cotyledons from the last two seedlings. After two weeks compare the growth of the bean plants. The plants with both cotyledons have developed best, and those without cotyledons have developed worst. Note that the cotyledons which were not cut off have shrivelled. When you remove a cotyledon the seedling gets less nutrients and it may starve.

9.9.13 Natural growth inhibitors
See diagram 9.3.49
1. The formation of growth inhibitors in the immediate vicinity of the embryos, e.g. in the endosperm, in the seed coats, in the pulp, may prevent the premature germination of seeds. Put seeds of garden cress, in a Petri dish with water for ten minutes and allow them to swell.
Put absorbent paper moistened with water in 4 Petri dishes and add the following:
Dish 1: a thin slice of apple,
Dish 2: a thin slice of orange,
Dish 3: a thin slice of tomato,
Dish 4: absorbent paper only (control).
2. Put ten swollen cress seeds on each of the fruit slices and also on the filter paper in the Dish 4, the control. Put lids on the dishes and leave at room temperature After 48 hours the cress seeds laid on the slices of fruit have hardly altered. However, the seeds on the filter paper in the control dish have germinated. They have grown a small root 10 to 20 mm long. In most instances the first tiny leaves can also be seen. The flesh of apple, tomato and orange all contain growth inhibitory substances. To ensure germination, seed must be separated from the old surrounding fruit tissue.

9.9.14 Zone of elongation of growing root
See diagram 9.102: Growth of broad bean radicle
The increase in root length results from growth occurring a small zone, the extension zone, which is situated just behind the tip of the root. It is only a few millimetres long and usually ends just where the root hairs begin Use four bean seedlings having straight roots 3 cm long, and apply, with a fine hair brush, 15 to 20 horizontal ink lines, each 1 mm apart, on the root, starting immediately behind the tip. A glass container is filled to a depth of 2 cm with water. The bean seedlings are placed on the cork disc, with 7 holes in it, the roots are stuck through the holes, and, with help, the disc is hung from the hooks in the glass container and the glass plate is placed on top. So that the roots will continue to grow, as far as possible, under normal light conditions, a blackout cover is placed over the glass container After 24 hours a marked increase in root length can be seen. The ink lines have been pulled different distances. The lines at the bottom, immediately behind the tip of the root, have not parted very much, the following lines have a much greater distance between them. The top lines are closer still and may not have moved at all. When the roots grow, the ink marks are pulled apart, the distance corresponding to the amount of extension growth in that particular root section.

9.9.17 Growth of plants in the classroom without soil
See diagram 9.3.46: Grow potato without soil
Put a potato, sweet potato, arrowhead vine, and tops of carrot, beet, turnip, pineapple in a container and keep the lower third covered with water or mineral water. Press toothpicks or matches into the sides to rest the plant parts on the rim of the container. The tops produce foliage but not new plants.

9.3.17 Post-fertilization changes outside the ovule

Hermaphrodite flowers .	Stamens and pistil in the same flower, Most familiar flowers, legumes, rose, potato, Grevillea, Primula
Monoecious (unisexual) (diclinous)	Stamens and pistil in separate flowers on the same plant, beech, oaks, hazel, sycamore
Dioecious (unisexual) .	Stamens and pistil in separate flowers on different plants, date palm, willow, poplar, hop

9.3.18 Fate of flower parts, floral organs

Ovule	Seed
Integuments	Seed coats
Nucellus	Shrivels to thin papery layer
Fusion nucleus of the embryo sac	Endosperm tissue for food storage and nutrition of the embryo .
Ovum	Embryonic plant
Antipodals .	Usually shrivel, sometimes persists as absorbing mechanism for endosperm
Synergids	Usually shrivel and are absorbed by the developing embryo

The ovule becomes a seed. The ovum (egg) inside the ovule becomes the embryo plant (baby plant). The calyx, corolla, stamens, stigma and style usually shrivel and fall off. The ovary forms a fruit. Examine the flowers of a plant and follow the fate of the different parts of the flowers until mature fruit forms.

9.5.0.1 Fruit classification

Fruit type	Name	Description	Examples
Dry indehiscent fruits	Achene	1 carpel, one seed attached to hard pericarp	Compositae family, buttercup, Clematis (strawberry, rose) cashew, sunflower
"	Caryopsis or grain	usually 1 carpel, ovary wall, pericarp and seed coat, testa, fused together	cereals, grasses, wheat, maize, rice
"	Samara	pericarp forms wings	maple, sycamore, ash
"	Cypsela	2 carpels, like achene but inferior ovary	Compositae family, dandelion, sunflower, daisy
"	Schizocarp	syncarpous ovary splits when ripe	geranium, mallow, hollyhock
"	Nut	more than 1 carpel, woody wall	macadamia nut, hazel nut .
Dry dehiscent fruits	Follicle	1 carpel, dehisce along one margin	oleander, larkspur, grevillea, kurrajong, columbine
"	Legume, pod	1 carpel, dehisce along both margins	Family Fabaceae, pea, bean, lentil, acacia, peanut (ground nut) cowpea, tamarind, fumewort, spiderflower
"	Lomentum	1 carpel, legume pod constricted between seeds	clover, cassia, bird's foot trefoil
"	Siliqua (silicule)	1 carpel, legume with constrictions between seeds	pod of Family Cruciferae, shepherd's purse, stock, cabbage
"	Capsule	3+ carpels, dehisce by pores or splits	Eucalyptus, tea tree, poppy, lily pansy, violet, iris, snapdragon, scarlet pimpernel, cotton, castor oil, kapok, okra, roselle, opium
True succulent fruits, fleshy fruits . .	Berry	2+ carpels, pericarp = skin epicarp, fleshy or fibrous mesocarp, thin skin endocarp (pepo or gourd has one cavity, pulp interior)	chillies, tomato, capsicum, eggplant, banana, gooseberry, date, currant, grape, avocado, papaya, passionfruit, allspice (pimento), pomegranate, guava, mangosteen, carambola (star fruit) (pepo: pumpkin, melon, cucumber, marrow, squash, snake gourd)
"	Drupe	1 superior carpel, pericarp = skin epicarp, fleshy or fibrous mesocarp, thin skin endocarp stony endocarp encloses seed (kernel)	apricot ("stone fruit"), almond, cashew, cherry, cocoa, coconut, coffee, mango, nutmeg, peach, pepper, plum, (walnut has 2 carpels, so a walnut is not a "nut")
False succulent fruits	Pome	"core" = ovary, fleshy receptacle .	apple, pear, quince
"	Hesperidum	many fused carpels, with pulp and tough rind containing oil glands	grapefruit, lemon, lime, orange, (citrus fruit)
"	Aggregate fruit, syncarp	collection of several carpels from one flower	pineapple, custard apple, rose hip (achenes) strawberry (achenes) blackberry, breadfruit, jack fruit, fig (called syconium) raspberry, blackberry, mulberry, pandanas