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Flowers, Fruits, and Seeds
Chapter 8
Copyright © McGraw-Hill Companies PermissionRequired for Reproduction or Display
Outline
• Dicots versus Monocots• Structure of Flowers• Fruits
Fleshy Dry
• Fruit and Seed Dispersal• Seeds
Germination Longevity
Dicots versus Monocots
• Dicots (Magnoliopsida)• Two cotyledons• Flower parts in fours or
fives• Leaves with distinct
vein network• Vascular cambium
present• Vascular bundles in
ring• Pollen grain with three
apertures
• Monocots (Liliopsida)• One cotyledon• Flower parts in threes• Leaves with parallel
primary veins.• Vascular cambium
absent• Vascular bundles
scattered• Pollen grain with one
aperture
Structure of Flowers
• Each flower, which begins as an embryonic primordium that develops into a bud, occurs as a specialized branch at the tip of a peduncle which may have branchlets of pedicles. Pedicle swells at its tip into a small pad
(receptacle).- Other parts of the flower are attached to
the receptacle.
Structure of Flowers
• Outermost whorl typically consists of three to five sepals. Sepals (calyx) may
be fused together.• Next whorl consists of
three to many petals (corolla). Calyx and corolla
form the perianth.
Structure of Flowers• Several to many stamens
are attached to the receptacle around the base of the pistil. Each stamen consists of
a filament with an anther at the top.
- Pollen grains developed and disseminated in anthers.
Structure of Flowers
• Pistil consists of Stigma, Style, and Ovary. Superior Ovary - Calyx
and corolla are attached to the receptacle at the base of the ovary.
Inferior Ovary - Receptacle grows up and around the ovary.
- Calyx and corolla appear to be attached at the top.
Gymnosperms flowers
Sago palm, however not a true palm: The generic name comes from Greek Koikas, and means "a kind of palm".
About 95 species are currently accepted in the cycad family Cycadaceae.
Gymnosperms flowers
Polen cones-male strobili
Seed cones-female strobili Pollen grains
Monocot flowers
Dicot flowers
Structure of Flowers• Inflorescences - Group of several to
hundreds of flowers
Fruits
• Fruit is an ovary and its accessory parts that have developed and matured. Usually contains seeds. All fruits develop from flower ovaries and
accordingly are found exclusively in flowering plants.
Fruits
• Fruit Regions Exocarp - Skin Endocarp - Inner
boundary around seed(s).
Mesocarp - Fleshy tissue between exocarp and endocarp.
- Three regions are collectively called the pericarp.
Fruits
• Fleshy Fruits Simple fleshy fruits develop from a flower with a
single pistil.- Drupe - Simple fleshy fruit with a single seed
enclosed by a hard, stony endocarp, or pit. E.g,; coconuts,apricot, peach,plum, almond
Fruits
• Berry - Usually develops from a compound ovary and often contains more than one seed. Three types of berries: True berry is a fruit with a thin skin and a
relatively soft pericarp.E.g.;tomatoes, grapes, peppers, eggplants, blueberries, cranberries, pomegrantes.
Fruits
Pepos - Relatively thick rinds (Pumpkins).
Fruits
Hesperidium – Berry with a leathery skin (citrus family)
Fruits• Pomes - Bulk of flesh comes from enlarged floral tube
or receptacle that grows up around the ovary. (Apples)• –Acessory fruits: Fruits developed from more than an
ovary alone i.e. Pomes, pepos and some berries
Fruits
• Aggregate Fruits Derived from a single flower with several to
many pistils.- Individual pistils mature as a clustered
unit on a single receptacle Raspberries, Strawberries.
Aggregate fruits/Raspberries, blackberries
Aggregate fruits/Raspberries, blackberries
Individual pistils
Fruits
• Multiple Fruits Derived from several to many individual
flowers in a single inflorescence. - Pineapples, Figs, Mulberries
Multiple fruits/Pineapples, figs
Fruits
• Dry Fruits That Split at Maturity (Dehiscent) Follicle - Splits along one side or seam
(Milkweed). Legume - Splits along two sides or seams
(Beans, peas,garbanzo beans, lentils,carob, peanuts!).
Silique - Splits along two sides or seams, but seeds are borne on central partition, exposed when the two halves separate (Cabbage, broccoli).
Capsules - Consist of at least two carpels, and split in a variety of ways (Poppies, Lilies).
Silicles-Lunaria (Dollar plant)
Follicles-Milkweed)
Capsule-Orchid
Fruits• Dry Fruits That Do Not
Split at Maturity (Indehiscent) Achene (Sunflower) Nut (filberts=Hazelnut) Grain (Poaceae fam.) Samara( ashes, elms) Schizocarp (parsley,
carrots)
Fruits
• Dry Fruits That Do Not Split at Maturity (Indehiscent) Schizocarp: Twin
fruit (parsley, carrots, anis, dill). Upon drying twin fruits break into two one-seeded segments called mericarps
Fruit and Seed Dispersal
• Wind Dispersal Small and Lightweight
seeds.• Animal Dispersal
Seeds pass through digestive tract.
Fruits and seeds catch in fur or feathers.
Oils attract ants.• Water Dispersal
Some fruits contain trapped air.
• Mechanical Ejection of Seeds
Seed dispersal
Pine Life Cycle
Seeds
Embryo shoot: Plumule
Embryo root: radicle
SEED GERMINATION (DICOTS)
• Structure Cotyledons - Food
storage organs that function as first seed leaves.
Plumule - Embryo shoot.
Epicotyl - Stem above cotyledon.
Hypocotyl - Stem below attachment point.
Radicle - Stem tip developing into a root.
Ovule-ovary attachment point
SEED GERMINATION (MONOCOTS)
Germination
• Germination is the beginning or resumption of seed growth. Seed must be viable.
- Some require a period of dormancy.To break the dormancy artificial techniques might be used such as:
- Scarification: Reduce thickness of the coat- After Ripening: Remove inhibitors- Stratification: Cold requirement mimic
Favorable Environmental Factors- Imbibe water- Temperature: Above freezing but below 45- Light: Required in some (lettuce) but unwanted in
others (California poppy)
Longevity
• Viability of most seeds is significantly extended when the seeds are stored under conditions of low temperatures and kept dry.
- Aquatic lotus-1000 years- Arctic tundra lupine-10 000 years- Willow,orchids, cottonwood and tea-viable for only a few days- Cantoloupe, squash, cucumber- several years- Onion, leek- 2-3 years- Wheat with proper storage:30 years with 30 % viability
1879-William J. Beal- Experiment with 1000 seeds from 20 species of weeds
- every 5 years, after 1920 every 10 years- In 1884 –most seeds of weeds germinated- In 1960-evening primrose, curly dock, moth mullein seeds germinated- In 1980 29 moth mullein, 1 mullein and 1 mallow seeds germinated- Six of original boxes are remaining and scheduled to be open in 2040
A few species produce seeds with no period of dormancy.- Vivipary
Rhizophora mangle (Vivipary)
Review
• Dicots versus Monocots• Structure of Flowers• Fruits
Fleshy Dry
• Fruit and Seed Dispersal• Seeds
Germination Longevity
Copyright © McGraw-Hill Companies Permission Required for Reproduction or Display
Oriental Sacred Lotus/ Nelumbo nucifera