1. Flowers, Fruits, and Seeds
Chapter 8

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 2 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
2 major classes of flowering plants:
Magnoliopsida (dicots)
Liliopsida (monocots)

5. Dicots
Monocots
2 cotyledons
1 cotyledon
Flower parts in multiples of 4 or f5
Flower parts in multiples of 3
Leaves with distinct network of veins
Leaves with parallel 1° 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 3 apertures
Pollen grains with 1 aperture

6. Structure of Flowers
Flowers begin as embryonic primordium that develops into 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

7. Structure of Flowers

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 1 to several carpels

9. Structure of Flowers
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

10. Structure of Flowers
Flowers can be produced singly or in inflorescences
Inflorescence - group of flowers

11. Fruits Fruit - matured ovary and its accessory parts Contains seeds
Develop from flower ovaries and found exclusively in flowering plants
Tomato fruit

12. Fruits Fruit Regions Exocarp – skin
Endocarp - inner boundary around seed(s)
Mesocarp - tissue between exocarp and endocarp
Peach fruit
3 regions collectively called pericarp

13. 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 1 or more ovaries

14. 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)

15. Fruits Simple fleshy fruits Berry
From compound ovary, with > 1 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

16. Fruits Berry cont’d. Hesperidium - leathery skin containing oils
Citrus
Pome – flesh from enlarged floral tube or receptacle that grows up around ovary
Endocarp papery or leathery
Apple pomes
Apples, pears - core
and little of adjacent tissue from ovary; remainder from floral tube and receptacle

17. Fruits Dry Fruits - mesocarp dry at maturity Dehisicent or indehiscent
Dehiscent fruits - split at maturity
Follicle - splits along 1 side
Larkspur, milkweed, peony
Legume - splits along 2 sides
Legume family: peas, beans, lentils, peanuts
Milkweed follicle
Legumes

18. Fruits Dehiscent fruits cont’d.
Siliques and Silicles - split along 2 sides, but seeds on central partition, which is exposed when 2 halves separate
Silicle
Silique - more than 3 times longer than wide
Silicle - less than 3 times longer than wide
Mustard family: broccoli, cabbage
Silique

19. Fruits Dehiscent fruits cont’d.
Capsules - consist of at least 2 carpels, and split in variety of ways
Irises, poppies, violets, snapdragons
Capsules

20. Inside of sunflower achene
Fruits
Indehiscent Fruits – don’t split at maturity
Single seed united with pericarp
Achene - base of seed attached to pericarp
Sunflower seed, buttercup, buckwheat
Inside of sunflower achene

21. Fruits Indehiscent Fruits cont’d.
Nut - similar to achene, but larger, with harder and thicker pericarp, and cluster of bracts at base
Acorns, hazelnuts, hickory nuts
Acorn

22. Schizocarp of mericarps
Fruits
Corn section
Indehiscent Fruits cont’d.
Grain (Caryopsis) - pericarp tightly united with seed
Grasses: corn, wheat, rice, oats
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

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

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

25. 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

26. Seeds Structure Ovules develop into seeds
Cotyledons - food storage organs that function as “seed leaves”
Embryo - cotyledons and plantlet
Plumule - embryo shoot
Bean seed

27. Seeds Structure cont’d. Epicotyl - stem above cotyledon attachment
Hypocotyl - stem below cotyledon attachment
Radicle - tip of embryo that develops into root
Bean seed

28. Seeds Epigeous 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 don’t emerge above surface

29. Germination Germination - 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 a few cells when fruit ripens; seeds won’t germinate until embryo develops

30. Germination Favorable environmental factors needed for germination
H2O and O2
Light or its absence
Proper temperature range
Enzymes in cytoplasm begin to function after H2O imbibed

31. 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 still on parent
Vivipary in red mangrove

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