1. Flowers, Fruits, and Seeds
Chapter 8
Lecture Outline
Flowers, Fruits, and Seeds
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2. Outline Introduction Differences Between Dicots and Monocots
Structure of Flowers
Fruits
Fruit and Seed Dispersal
Seeds

3. Introduction Annual plants - Cycle completed in single season.
Cycle = from seed germination to mature plant producing seeds
Biennial plants - Cycle completed in two growing seasons.
Perennial plants - Cycle takes several to many growing seasons or plant produces flowers on new growth, while other plant parts persist indefinitely.

4. Differences Between Dicots and Monocots
Two major classes of flowering plants:
Magnoliopsida (dicots) and Liliopsida (monocots)
Dicots
Monocots
Two cotyledons
One cotyledon
Flower parts in multiples of four or five
Flower parts in multiples of three
Leaves with distinct network of veins
Leaves with parallel primary veins
Vascular cambium and cork cambium present
Vascular cambium and cork cambium absent
Vascular bundles of stem in ring
Vascular bundles of stem scattered
Pollen grains with three apertures
Pollen grains with one aperture

5. Structure of Flowers
Flowers begin as embryonic primordium that develops into a bud.
Flowers occur as specialized branches at tips of peduncles.
May have branchlets of pedicels
Receptacle - Swollen end of peduncle or pedicel
Other parts of flower attached to receptacle in whorls: sepals, petals, stamens, and pistil.

6. Structure of Flowers Sepals - Outermost whorl
Collectively referred to as calyx
Protects flower while in bud
Petals - Next whorl inside sepals
Collectively referred to as corolla
Showy corollas attract pollinators.
Inconspicuous or missing corollas in many trees, weeds, grasses, and wind-pollinated plants
Calyx and corolla form perianth.

7. Structure of Flowers Stamens attached around base of pistil.
Each stamen consists of filament with anther at top.
Pollen grains developed in anthers.
Pistil consists of stigma, style, and ovary.
Ovary develops into fruit.

8. Structure of Flowers
Ovaries evolved from carpels with margins rolled inward.
Carpel - Leaf with ovules on margins
Carpels may be fused together into compound ovary.
Pistil can consist of one to several carpels.
Superior Ovary - Calyx and corolla attached to receptacle at base of ovary.
Inferior Ovary - Receptacle grows up and around the ovary.
Calyx and corolla appear attached at top of ovary.
Ovary contains ovules.
Ovules develop into seeds after fertilization.

9. Structure of Flowers
Flowers can be produced singly or in inflorescences.
Inflorescence - Group of flowers

10. Fruits Fruit - Matured ovary and its accessory parts Contains seeds
All fruits develop from flower ovaries and accordingly are found exclusively in flowering plants.
Tomato fruit

11. Fruits Fruit Regions Exocarp - Skin
Endocarp - Inner boundary around seed(s)
Mesocarp - Tissue between exocarp and endocarp
Peach fruit
Three regions collectively called pericarp.

12. Fruits Variability of fruits Can consist of only ovary and seeds
Can include adjacent flower parts
May be fleshy or dry at maturity
May split or not split
May be derived from a one or more ovaries

13. Drupes: peaches, almonds, olives
Fruits
Fleshy Fruits - Mesocarp at least partly fleshy at maturity.
Simple fleshy fruits develop from flower with single pistil.
Drupes: peaches, almonds, olives
Drupe - Simple fleshy fruit with single seed enclosed by hard, stony endocarp (pit)

14. Fruits Simple fleshy fruits Berry
From compound ovary, with more than one seed, and with fleshy pericarp
True berry - With thin skin and relatively soft pericarp
Tomatoes, grapes, peppers, blueberries, bananas
Pepo - Relatively thick rind
Pumpkins, cucumbers
Grape berries

15. Fruits Berry Hesperidium - Leathery skin containing oils Citrus
Pome - Flesh comes from enlarged floral tube or receptacle that grows up around ovary.
Endocarp papery or leathery
Apples, pears - Core and a little of adjacent tissue is from ovary; remainder is from floral tube and receptacle
Apple pomes

16. Fruits Dry Fruits - Mesocarp dry at maturity
Dehisicent or indehiscent
Dehiscent fruits - Split at Maturity
Follicle - Splits along one side
Larkspur, milkweed, peony
Legume - Splits along two sides
Legume family: peas, beans, lentils, peanuts
Milkweed follicle
Legumes

17. Fruits Dehiscent fruits
Siliques and silicles - Split along two sides, but seeds on central partition, which is exposed when two halves separate.
Silicle
Silique - More than three times longer than wide
Silicle - Less than three times longer than wide
Mustard family: broccoli, cabbage
Silique

18. Fruits Dehiscent fruits
Capsules - Consist of at least two carpels, and split in a variety of ways
Irises, poppies, violets, snapdragons
Capsules

19. Inside of sunflower achene
Fruits
Dry Fruits
Indehiscent Fruits - Do Not Split at Maturity
Single seed united with pericarp
Achene - Base of seed attached to pericarp.
Sunflower seed, buttercup, buckwheat
Nut - Similar to achene, but larger, with harder and thicker pericarp, and a cluster of bracts at base
Acorns, hazelnuts, hickory nuts
Inside of sunflower achene
Acorn

20. Schizocarp of mericarps
Fruits
Corn section
Indehiscent Fruits
Grain (Caryopsis) - Pericarp tightly united with seed
Grasses: corn, wheat, rice, oats, barley
Samara - Pericarp extends as wings for dispersal.
Maples, ashes, elms
Samaras
Schizocarp - Twin fruit that breaks into one-seeded segments called mericarps
Schizocarp of mericarps
Parsley family: carrots, anise, dill

21. Fruits Aggregate Fruits Multiple Fruits
Derived from single flower with several to many pistils
Individual pistils mature as clustered unit on single receptacle.
Blackberry aggregate fruits
Raspberries, blackberries, strawberries
Osage orange multiple fruit
Multiple Fruits
Derived from several to many individual flowers in single inflorescence
Mulberries, Osage orange, pineapples, figs

22. Fruit and Seed Dispersal
Dispersal by Wind
Fruits: Samaras, plumes or hairs on fruit
Seeds: Small and lightweight, or with wings

23. Fruit and Seed Dispersal
Dispersal by Animals
Seeds pass through digestive tract.
Fruits and seeds adhere to fur or feathers.
Oils attract ants.
Elaiosomes on bleeding hearts used as food by ants.
Seeds from bleeding hearts. Elaiosome is white.
Water Dispersal
Some fruits contain trapped air for floatation.

24. Seeds Structure Ovules develop into seeds.
Cotyledons - Food storage organs that function as “seed leaves”
Embryo = cotyledons and plantlet
Plumule - Embryo shoot
Bean seed
Epicotyl - Stem above cotyledon attachment
Hypocotyl - Stem below cotyledon attachment
Radicle - Tip of embryo that develops into root

25. Seeds Epigeous germination Hypogeous germination
Hypocotyl lengthens, bends and becomes hook-shaped.
Top of hook emerges from ground, pulling cotyledons above ground.
Epigeous germination
Hypogeous germination
Hypocotyl remains short and cotyledons do not emerge above surface.

26. Germination Germination is beginning or resumption of seed growth.
Some require period of dormancy.
Brought about by mechanical or physiological factors, including growth-inhibiting substances present in seed coat or fruit
Break dormancy by mechanical abrasion, thawing and freezing, bacterial action, or soaking rains.
Scarification - Artificially breaking dormancy
After ripening - Embryo composed of only of few cells when fruit ripens; seeds will not germinate until embryo develops.

27. Germination Favorable environmental factors needed for germination.
Water and oxygen
Light or its absence
Proper temperature range
Enzymes in cytoplasm begin to function after water is imbibed.

28. Vivipary in red mangrove
Longevity
Seed viability varies, depending on species and storage conditions.
Viability extended:
At low temperatures
When kept dry
Vivipary - No period of dormancy; embryo continues to grow while fruit is still on parent.
Vivipary in red mangrove

29. Review Introduction Differences Between Dicots and Monocots
Structure of Flowers
Fruits
Fruit and Seed Dispersal
Seeds