Plant Morphology and Reproduction PDF

Pollination Ecology ❖ Butterfly- and moth-pollinated flowers: Often have sweet fragrances White or yellow for night-flying moths Sometimes red, often blue, yellow or orange for butterflies Nectaries at bases of corolla tubes or spurs for long tongues. Pollination Ecology Bird-pollinated flowers (hum...

Pollination Ecology ❖ Butterfly- and moth-pollinated flowers: Often have sweet fragrances White or yellow for night-flying moths Sometimes red, often blue, yellow or orange for butterflies Nectaries at bases of corolla tubes or spurs for long tongues. Pollination Ecology Bird-pollinated flowers (hummingbirds and sunbirds): ❖ Often bright red or yellow Little if any odor - Birds do not have a keen sense of smell. Large and part of sturdy inflorescence Copious amounts of nectar - Birds highly active. Long floral tubes Pollination Ecology ❖ Bat-pollinated flowers: Primarily in tropics Open at night when bats are foraging Dull in color Large enough for bat to insert head or consist of ball-like inflorescence containing large numbers of small flowers Pollination Ecology ❖ Orchid flowers: Have pollinators among all types mentioned Some of adaptations between orchid flowers and pollinators are extraordinary. Pollen grains produced in little sacs called pollinia (singular: pollinium) with sticky pads at base. Members of Ophrys have modified petal that resembles female bumble bee or wasp. – Male bees or wasps try to copulate with flower. o Pollinia deposited on their head. Drug Dealers ❖ Caffeine Used to give bees a buzz Helps make a faithful “hooked” pollinator Drug Dealers ❖ Nectar (not a drug) Highly nutritious Hummingbirds and Heliconia sp. – Just enough nectar production Botanical Trickery ❖ Bee Orchid (Ophrys apifera) Instigators! ❖ Naughty Orchids Resemble aggressive bee Ouch! ❖ Some plants beat their pollinators into submission Warty Hammer Orchid 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 Vegetable = any edible portion of a plant Fruit Regions ❖ ❖ ❖ Exocarp – Skin Endocarp - Inner boundary around seed(s) Mesocarp - Tissue between exocarp and endocarp – Peach fruit Three regions collectively called pericarp. Fruits Variability ❖ 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 Fruits ❖ ❖ Fleshy Fruits - Mesocarp at least partly fleshy at maturity. Simple fleshy fruits develop from flower with single pistil. Drupe - Simple fleshy fruit with single seed enclosed by hard, stony endocarp (pit) Drupes: peaches, almonds, olives 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 o – Tomatoes, grapes, peppers, blueberries, bananas Pepo - Relatively thick rind o Pumpkins, cucumbers Grape berries Fruits Berry – Hesperidium - Leathery skin containing oils o Citrus Fruits Berry – Pome - Flesh comes from enlarged floral tube or receptacle that grows up around ovary. o Endocarp papery or leathery o Apples, pears - Core and a little of adjacent tissue is from ovary; remainder is from floral tube and receptacle Fruits ❖ Dry Fruits - Mesocarp dry at maturity Dehiscent 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 Fruits: Dry Dehiscent ❖ Siliques and silicles - Split along two sides, but seeds on central partition, which is exposed when two halves separate. – Silique - More than three times longer than wide – Silicle - Less than three times longer than wide – Mustard family: broccoli, cabbage Silicle Silique Fruits: Dry Dehisccent ❖ Capsules - Consist of at least two carpels, and split in a variety of ways Irises, poppies, violets, snapdragons A. C. Autograph Tree D. Unicorn plant Fruits: Dry Indehiscent ❖ Indehiscent Fruits - Do Not Split at Maturity Single seed united with pericarp – – Achene - Base of seed attached to pericarp. o Sunflower seed, buttercup, buckwheat Nut - Similar to achene, but larger, with harder and thicker pericarp, and a cluster of bracts at base o Acorns, hazelnuts, hickory nuts Inside of sunflower achene Acorn Fruits: Dry Indehiscent ❖ Grain (Caryopsis) - Pericarp tightly united with seed Grasses: corn, wheat, rice, oats, barley Samaras Corn section Schizocarp of mericarps Schizocarp - Twin fruit Samara - Pericarp that breaks into oneseeded segments called mericarps extends as wings for dispersal. – Maples, ashes, elms – Parsley family: carrots, anise, dill ❖ Aggregate Fruits Derived from single flower with several to many pistils – o ❖ Individual pistils mature as clustered unit on single receptacle. Raspberries, blackberries, strawberries Blackberry aggregate fruits Multiple Fruits Derived from several to many individual flowers in single inflorescence – Mulberries, Osage orange, pineapples, figs Osage orange multiple fruit Fruit and Seed Dispersal ❖ Dispersal by Wind Fruits: Samaras, plumes or hairs on fruit Seeds: Small and lightweight, or with wings 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. Fruit and Seed Dispersal ❖ Water Dispersal Some fruits contain trapped air for floatation. Ho d 1i V I d.i i r, 11ni , I Explosive dehiscence of Jewelweed (Impatiens capensis) https://www.youtube.com/watch?v=48YAHg-kY10 Seeds: An important adaptation ❖ Maintain Dormancy ❖ Afford maximum protection ❖ Contain Stored food ❖ Adapted for Dispersal Specialized Adaptations: – Sometimes seeds are in tough cones that do not open until they are exposed to fire – Some germinate only after inhibitory chemicals leach out of the seed coat. ❖ Structure Seeds Ovules develop into seeds. – Cotyledons - Food storage organs that function as “seed leaves” – Embryo = cotyledons and plantlet – Plumule - Embryo shoot – Epicotyl - Stem above cotyledon attachment – Hypocotyl - Stem below cotyledon attachment – Radicle - Tip of embryo that develops into root Bean seed Seed Germination ❖ Epigeous germination Hypocotyl lengthens, bends and becomes hook-shaped. Top of hook emerges from ground, pulling cotyledons above ground. Seed Germination ❖ Hypogeous germination Hypocotyl remains short and cotyledons do not emerge above surface. 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. o Scarification - Artificially breaking dormancy After ripening - Embryo composed of only of few cells when fruit ripens; seeds will not germinate until embryo develops. Seed Germination ❖ Environmental requirements for germination Availability of oxygen for metabolic needs Adequate temperature for enzyme activity Adequate moisture for hydration of cells Light (in some cases) Scarification: break dormancy due to alterations in seed coat. – Heat, cold, animal intestinal acid, soil microbes ❖ Respiration and metabolism continue throughout dormancy, but at a reduced level 98 Longevity ❖ Seed viability varies, depending on species and storage conditions. Viability extended: – At low temperatures and when kept dry Some seeds can remain dormant for an indeterminent amount of time refereed to as seed bank. Longevity ❖ Vivipary - No period of dormancy; embryo continues to grow while fruit is still on parent. Vivipary in red mangrove Common Plant Families ❖ Magnoliaceae (Magnolia) ❖ ❖ ❖ Juglandaceae (Walnut) ❖ ❖ ❖ ❖ ❖ Cactaceae (Cactus) Brassicaceae (Mustard) Cucurbitaceae (Pumpkin) Asteraceae (Sunflower) ❖ Poaceae (Grass) ❖ Orchidaceae (orchid) ❖ Agavaceae (agave) Rosaceae (Rose) Fabaceae (Pea) Solanaceae (Potato) Family Magnoliaceae (Magnolias) Family Magnoliaceae (Magnolias) Family Juglandaceae (Walnut) Family Cactaceae (Cactus) Cactaceae Diversity Family Cactaceae (Cactus) Family Brassicaceae (Mustard) Family Brassicaceae (Mustard) Family Rosaceae (Rose) Family Rosaceae (Rose) Family Fabaceae (Pea/Legume) Family Fabaceae (Pea/Legume) Family Solanaceae (Potato) Family Cucurbitaceae (Pumpkin) Family Cucurbitaceae (Pumpkin) Family Asteraceae (Sunflower) Family Asteraceae (Sunflower) Family Poaceae (Grass) Family Poaceae (Grass) Family Orchidaceae (orchid) Family Orchidaceae (orchid) Grass Pink (Calopogon tuberosus) Family Orchidaceae (orchid) Family Agavaceae (agave)