Chapter 31.4

1. Chapter 31.4 From Zygotes to Seeds and Fruits AP Biology Spring 2011

2. Ovule Positions Making a lateral cut through an ovary of different flowering plants shows variation Some are divided into more than one chamber, with more than one ovule attached to the ovary wall Part of the wall may become a tissue mass in the center of the ovary Figure on page 532

3. The Embryo Sporophyte • Variation in embryo sporophyte development • Ex. Shepherd’s purse- eudicot • Two cotyledons which develop from 2 lobes of meristematic tissue • Embryos absorbs nutrients from endosperm and stores them in cotyledons

4. The Embryo Sporophyte • Ex. Monocots: • Monocots have one cotyledon • Most monocot embryos do not tap into nutritive tissue until after germination

5. Seed and Fruit Formation Until embryo sporophyte fully formed, parent plants transfer nutrients to ovule’s tissue Food accumulates in endosperm or in coyledons

6. Seed and Fruit Formation • Ovule will eventually pull away from ovary wall • Seed coat forms • Embryo, food reserves, and coat = seed • Seed = mature ovule

7. Seed and Fruit Formation • Only flowering plants make seeds in ovaries, and only they make fruits • Several ways to categorize fruit • Origin • Composition • Appearance

8. Seed and Fruit Formation- Origin • Simple fruits: one flower, originate in a single or fused carpel • Ex. Cherries, apples

9. Seed and Fruit Formation- Origin • Aggregate fruits: one flower, originate in several unfused carpels and become a cluster of several fruits • Ex. Strawberries, raspberries

10. Seed and Fruit Formation- Origin • Multiple fruits: start out as a cluster of individually pollinated flowers that grow together and fuse into a single body • Ex. Figs, pineapples

11. Seed and Fruit Formation- Composition • True fruit: only the ovarian wall and its contents

12. Seed and Fruit Formation- Composition • Accessory fruit: other floral parts, such as the receptacle, expand right along with the ovary • Ex. Watermelons, apples

13. Seed and Fruit Formation- Appearance • Dry fruit: • Dehiscent: fruit wall splits along definite seams to release the seeds inside • Ex. Capsella pods and pea pods • Indehiscent: wall does not split open, seeds are dispersed inside intact fruit wall • Ex. Acorns, grains (corn), sunflowers, maples, strawberries

14. Seed and Fruit Formation- Composition • Fleshy fruit: • Drupe: have a pit (stone hard jacket around one seed; sometime more), and fleshy fruit that encloses the pit • Ex. Cheeries, peaches, apricots, almonds, olives

15. Seed and Fruit Formation- Composition • Fleshy Fruit: • Berry: has one to many seeds, no pit, and fleshy fruit • Ex. Grapes, tomatoes, lemons, oranges, grapefruit • Pepo: hard rind on ovary wall (pumpkins, watermelons, cucumbers) • Hesperidium: leathery rind on ovary wall (citrus fruits)

17. Seed and Fruit Formation- Composition • Pome: has seeds in a somewhat elastic core tissue and fleshy accessory tissues that encloses its core • Ex. Apples, pears

18. Seed and Fruit Formation • To categorize an apple: • Simple fruit: originates from one flower • Accessory fruit: fleshy receptacle expands around five carpels • Pome: carpels form an elastic core in fleshy accessory tisue