The fruits and the seeds.

Transcription

1 The fruits and the seeds.

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3 The Flower- Fruit Relation

4 Double Fertilization Double fertilization occurs: One sperm nucleus (1n) fertilizes the egg, producing a zygote (2n) which becomes the plant embryo inside the seed Another sperm nucleus fuses with the polar nuclei, resulting in a triploid endosperm (3n) Endosperm is a source of food for the young embryo. Endosperm

5 Flowers to Fruits Fruit (with 1+ seeds) Ovary (in flower) With ovules

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8 So What is a seed? A matured ovule, containing: 1. a plant embryo 2. a food supply 3. covered by a seed coat

9 Embryo The seed contains a well-formed multicellular young plant embryo (germ) (what used to be a zygote). Embryo is DIPLOID (2n) or two sets of chromosomes, one from the mother and one from the father. It will become a whole plant Endosperm-Starch Embryo-Germ Seed Coat-Bran

10 The endosperm Seed contains a food supply of nutritive tissue called the endosperm. It is 3 n. Stored food contains enough energy for the embryo to grow through the soil, when seedling is unable to photosynthesize.

11 Seed coat A thick protective coat outer layer of the seed Formed from the outside layers of the ovule. Seed coat

12 Dicot vs. monocot seed Dicot has two cotyledons (like bean) Endosperm (food) is kept in the cotyledons Monocot has one cotyledon which absorbs the endosperm tissue during germination (corn)

13 And what happened to the rest of the ovary? In flowering plants Fruit is a mature, ripened ovary that contains the seeds.

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15 Fruit Parts Pericarp: The fruit wall (derived from the ovary of the pistil) which is composed of the exocarp, mesocarp and endocarp (the three layers are not always recognizable, ex. dry fruit). Endocarp: The innermost layer of the pericarp (often hard, stony or papery). Mesocarp: The middle layer of the pericarp (often fleshy). Exocarp: The outermost layer of the pericarp (often like a skin or peel).

16 Rind: Tough, leathery covering on many fruits either composed of the exocarp (melon) or the exocarp and mesocarp (orange). Accessory tissue: Fruit parts not directly derived from the ovary, for example, receptacle tissue of pomes (apple) and the husks of nuts (acorn, pecan).

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18 Fruit Terms Major Distinctions: dry vs. fleshy dehiscent vs. indehiscent product of 1 ovary vs. 2+ ovaries product of 1 flower vs. multiple flowers

19 Fruit Types A. Simple fleshy and simple dry B. Aggregate C. Multiple D. Accessory

20 1. Berry 2. Hesperidium 3. Drupe 4. Pepo 5. Pome Simple fruit Simple fruits develop from a single ovary of single flower. Simple fruits can be either fleshy or dry when mature. Depending on the consistency of the fruit parts, fleshy simple fruits are classified into:

21 Simple Fleshy Fruit: Berry The exocarp, mesocarp and endocarp of a true berry are fleshy. Examples: Tomatoes.

22 Berry: multiple seeds, embedded in fleshy pulp

23 Simple Fleshy Fruit: Hesperidium The hesperidium has a thick leathery skin containing oils. Ex: Oranges, lemons, grapefruit

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25 Simple Fleshy Fruit: Drupe The drupe has a fleshy or soft exocarp, a fleshy mesocarp and a stony endocarp. Examples: Peach, apricot, plums.

26 Drupes are adapted to pass through the digestive system of an animal. In fact, some drupes require the scouring by digestive acids to allow the seed to germinate.

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28 Simple Fleshy Fruit: Pepo The exocarp of a pepo is a thick rind while the mesocarp and the endocarp are both fleshy. Examples: cucumbers, squash, pumpkin.

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30 Accessory Fruits Simple fruits develop from a single ovary of single flower. If the fruit uses the ovary and the receptacle is called an accessory fruit. Ovary Receptacle/ hypanthium

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33 Bartlett are the most popular variety of pears. Anjou, Bosc, Comice and Asian pears are other varieties. Quinces 90% of the apples grown in the United States, come from only 16 varieties of apples. 8 of these make up 80%?

34 Simple dry fruits Simple fruits from one ovary of one flower. Dry at maturity. Dehiscent: They open and shed their seeds. Splits opens along one side: Follicles Splits opens along both sides: Legumes Splits open along several seams: Capsule Indehiscent: Do not open

35 Dry, Dehiscent Fruits Follicle Follicle: From simple ovary, splits along 1 seam only Spiraea Fruits milkweed

36 Legumes Legumes are dry fruit that splits along two seams. Ex. Beans, peanuts, peas.

37 Simple dry fruit: capsule Capsule fruit is dry at maturity and splits open along several seams. Example: Cotton

38 Simple dry fruits, indehiscent Simple dry fruits that do NOT open at maturity (indehiscent). Caryopsis: seed coat is fused to the ovary wall (cereal grains like corn, wheat, rice) Nuts: single-ovary wall and seed coat remain separate, ovary wall is very hard (walnuts, pecans, acorns)

39 Aggregate Fruits These fruits develop from a flower with many separate carpels, thus each carpel produces a separate fruit. As the fruits develop, they fuse producing a single fruit. Examples: Raspberries, blackberries.

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41 Aggregate fruit develops from one flower with many separate pistils/carpels, all ripening simultaneously. Examples: strawberry, raspberries, blackberries

42 Multiple Fruits These fruits develop from all the flowers of an entire inflorescence. For example: pineapple, mulberry, syconium (figs).

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46 What is the purpose of the fruit? The main function of the fruit is to disperse the seeds. Dispersal is important because it spreads the progeny to new environments. Reduces competition for resources with parents. Four types of seed dispersal A. Self dispersal B. Wind dispersal C. Water dispersal D. Animal dispersal

47 Self dispersal Plants disperse their seeds by forceful ejection. These are commonly called explosive fruits! Witch hazel, squirting cucumber (jet propulsion)

48 The peanut plant sows (buries) its own seeds! Self dispersal Geocarpic: carpel grows inside the earth (soil)

49 Wind dispersal Fruit and seeds may have special devices for wind dispersal Plumes catch wind currents: Dandelion Trees take advantage of their great heights for wind dispersal. Fruits with wings are used to slow the descent to land: maple, ash fruit

50 Water Dispersal Fruits and/or seeds use flotation devices to travel by water (in rivers, oceans, etc.) Fruit may have air spaces and corky floats: coconut

51 Animal dispersal Plants have coevolved with animals to accomplish seed dispersal Many plants depend on animals for seed dispersal; they may offer a nutritional reward Animals learn to recognize ripened fruit colors Fleshy fruits eaten and dispersed with feces

52 Animal dispersal Some dry fruit attach and cling to animals (they hitchhike on the animals) Some have Velcro-like hooks that cling to animal fur (burdock, cockleburs) Others have sticky substances that stick to host

53 The End This class is really making me a pumpkin head