Fruits and seeds

FRUITS AND SEEDS Fruits ❚ Part of sexual reproduction unique to angiosperms ❚ Develops from fertilized ovary ❚ Protect the enclosed seeds and aids in seed dispersal ❚ Widely utilized as a significant food source Fruit wall or Pericar p ❚ Develops from the ovary wall ❚ Composed of three layers ❙ outer exocarp ❙ middle mesocarp ❙ inner endocarp ❚ Appearance of these three layers varies among different fruit types Fruit Types I: Simple Fruits ❚ Derived from the ovary of a single carpel or several fused carpels ❚ Can be fleshy or dry Type I.a: Simple fleshy fruit ❚ Derived from the ovary of a single carpel or several fused carpels ❚ Often soft and juicy ❚ Seed dispersal occurs when an animal eats the fruit ❚ Types of simple fleshy fruits ❙ BERRY ❙ DRUPE -HESPERIDIUM -POME -PEPO Ber r y ❚ Thin exocarp ❚ Soft fleshy mesocarp ❚ Endocarp with one to many seeds ❚ Tomatoes, grapes and dates Hesperidium ❚ Berry with a tough leathery rind ❚ Oranges, lemons, and other citrus fruitS Pepo ❚ Tough outer rind that has both receptacle tissue and exocarp ❚ Mesocarp and endocarp are fleshy ❚ All members of the squash family (pumpkins, melons, and cucumbers) Dr upe ❚ Thin exocarp ❚ Fleshy mesocarp ❚ Hard stony endocarp which encases the seed ❚ Cherries, peaches, and plums Exocarp Mesocarp Endocarp Pome ❚ Fleshy part develops from the enlarged base of the perianth (calyx and corolla) that is fused to the ovary wall ❚ Apples and pears Citrus Fruits Citrus Fruits - Oranges ❚ Members of the family Rutaceae ❚ Fruit is a hesperidium ❚ Rind impregnated with oil glands (oils important for perfumes and cosmetics) ❚ Individual carpels filled with one-celled juice sacs ❚ Fruits high in Vitamin C Citrus Fruits ❚ Most citrus are native to southeast Asia ❚ Citrons first citrus fruit introduced to Mediterranean countries during Greek and Roman times ❚ Sweet oranges not introduced till 16th century Introduction to New World ❚ Spanish and Portuguese explorers introduced citrus to New World ❚ Sour oranges grown in Florida by 1565 ❚ Sweet oranges introduced after 1821 - grafted onto sour orange rootstock ❚ Florida remains leading orange-producing state for juices ❚ Grapefruit developed in Caribbean (pummelo x orange) Pummelos Navel Orange ❚ Seedless orange - propagated asexually ❚ First developed in Brazil by an American missionary in 19th century ❚ Two seedlings introduced to California in 1873 - believed that all navel oranges today are descendants of these two trees Chestnuts - Castanea dentata ❚ Member of the Fagaceae - Oak Family ❚ Nuts have a long history of use ❚ Nuts produced in groups of surrounded by spiny burr (actually bracts) Spiny bracts Individual nuts Chestnuts ❚ American chestnut tree was once one of the most abundant trees in North American forests ❚ Wood widely used for furniture, shingles, poles, ships masts Chestnut Blight ❚ Fungal disease first reported in 1904 in New York ❚ Spread throughout range from Atlantic Coast to Mississippi River ❚ Estimated billion chestnut trees died ❚ Chestnuts can resprout from roots but eventually will succumb to disease ❚ Research on blight resistant trees Durian ❚ Fruit native to southeast Asia, Malaysia, Thailand, Indonesia ❚ Called “King of Fruits” Durians ❚ Large fruits - 10-15 lbs ❚ Often collected from wild although cultivation is spreading ❚ Not available outside of Asia ❚ Custard-like pulp that is said to be heavenly Durians ❚ Said to be the most delicious fruit on Earth and the worst smelling ❚ Sold in open markets but prohibited in many cities ❚ “No durians allowed” [...]... from the seed ❚ Sunflower seeds ❚ Winged achenes ❚ Dispersed by wind ❚ Fruit in maple trees and ash trees Grains ❚ ❚ ❚ ❚ Also called caryopsis Single seeded fruits Pericarp fused to seed coat Fruits of all cereal grasses: wheat, rice, corn and barley Wheat gr ain Fused seed coat and ovary wall layers Nuts ❚ One-seeded fruits ❚ Hard stony pericarps ❚ Hazelnuts, chestnuts, and acorns ❚ Other things...Accessor y fruits ❚ Contain flower parts other than the ovary ❚ Both the pepo and pome are example Type I.b: Simple dry fruits ❚ Derived from the ovary of a single carpel or several fused carpels ❚ Pericarp may be tough and woody or thin and papery ❚ Two types: ❘ dehiscent ❘ indehiscent Dr y dehiscent fruits ❚ Split open at maturity to release seeds ❚ Wind often aids seed dispersal... Multiple fruits ❚ Result from the fusion of ovaries from many separate flowers on an inflorescence ❚ Figs and pineapples are examples of multiple fruits one of many ovaries that are fused together Seed Structure and Ger m ination Seeds ❚ Develop from the fertilized ovules ❚ Include an embryonic plant and some form of nutritive tissue within a seed coat ❚ Because of the stored nutrients many seeds are... are actually seeds Fruit Types II: Aggregate fruits ❚ Develop from a single flower with many separate carpels ❚ Raspberries and blackberries ❚ Strawberries also contain accessory tissue ❙ Seeds on the surface are actually separate achenes inserted on the enlarged, fleshy, red receptacle Raspberries and Blackberries Aggre gate-Accessor y Fruit ❚ Strawberries also contain accessory tissue ❚ Seeds on the... (magnolia and milkweed) * Legume - splits open along two seams (beans and peas) * Capsule - several pores or slits (cotton and poppy) Legume - pea ❚ Legume pod splits along two seams to disperse seeds Capsule ❚ Cotton fruit is a capsule splitting open along five lines ❚ Seeds are covered with long hairs (trichomes) which are the commercial cotton fiber Indehiscent fr u its ❚ Do not split open to release seeds. .. nutritive tissue within a seed coat ❚ Because of the stored nutrients many seeds are valuable foods Dicots and monocots ❚ Refers to the number of seed leaves or cotyledons present in the seed ❚ Dicot seeds have two cotyledons ❚ Monocots have one cotyledons Dicot seed ❚ Cotyledons attached to and enclose the embryonic plant ❚ Cotyledons occupy the greatest part of the seed ❚ Cotyledons have absorbed... Hilum and micropyle visible on surface * Hilum - attachment * Micropyle - opening in the integuments ❚ If the seed coat is removed the two large food-storing cotyledons are visible Dicot embryo ❚ Consists of : ❙ Epicotyl - part that develops into the shoot; typically has embryonic leaves - also called a plumule ❙ Hypocotyl - portion of embryo between cotyledon attachment and radicle (between stem and. .. are present Monocot seeds - Corn kernel ❚ Reminder: a grain is a one-seeded fruit in which the seed coat is fused to the pericarp ❚ Extensive endosperm occupies much of the seed ❚ Small embryo with a single cotyledon ❚ Presence of a coleoptile and the coleorhiza Seed ger m ination ❚ Absorption of water ❚ Emergence of the radicle ❚ Shoot emerges: ❙ In dicots the hypocotyl elongates and breaks through... In dicots the hypocotyl elongates and breaks through the soil ❙ In monocots the coleoptile emerges protecting the epicotyl tip ❚ Soon after the tissues are exposed to sunlight, they develop chlorophyll and begin to photosynthesize  ... many seeds ❚ Tomatoes, grapes and dates Hesperidium ❚ Berry with a tough leathery rind ❚ Oranges, lemons, and other citrus fruitS Pepo ❚ Tough outer rind that has both receptacle tissue and exocarp... peaches, and plums Exocarp Mesocarp Endocarp Pome ❚ Fleshy part develops from the enlarged base of the perianth (calyx and corolla) that is fused to the ovary wall ❚ Apples and pears Accessor y fruits. .. ❚ Both the pepo and pome are example Type I.b: Simple dry fruits ❚ Derived from the ovary of a single carpel or several fused carpels ❚ Pericarp may be tough and woody or thin and papery ❚ Two