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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 Pericarp. Develops from the ovary wall Composed of three layers

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FRUITS AND SEEDS

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  1. FRUITS AND SEEDS

  2. 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

  3. Fruit wall or Pericarp • 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

  4. Fruit Types I: Simple Fruits • Derived from the ovary of a single carpel or several fused carpels • Can be fleshy or dry

  5. 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 -HESPERIDIUM -PEPO • DRUPE -POME

  6. Berry • Thin exocarp • Soft fleshy mesocarp • Endocarp with one to many seeds • Tomatoes, grapes and dates

  7. Hesperidium • Berry with a tough leathery rind • Oranges, lemons, and other citrus fruitS

  8. 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)

  9. Drupe • Thin exocarp • Fleshy mesocarp • Hard stony endocarp which encases the seed • Cherries, peaches, and plums Exocarp Mesocarp Endocarp

  10. Pome • Fleshy part develops from the enlarged base of the perianth (calyx and corolla) that is fused to the ovary wall • Apples and pears

  11. Accessory fruits • Contain flower parts other than the ovary • Both the pepo and pome are example

  12. 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

  13. Dry dehiscent fruits • Split open at maturity to release seeds • Wind often aids seed dispersal • Types characterized by how they open: • Follicle - splits open along one seam (magnolia and milkweed) • Legume - splits open along two seams (beans and peas) • Capsule - several pores or slits (cotton and poppy)

  14. Legume - pea • Legume pod splits along two seams to disperse seeds

  15. Capsule • Cotton fruit is a capsule splitting open along five lines • Seeds are covered with long hairs (trichomes) which are the commercial cotton fiber

  16. Indehiscent fruits • Do not split open to release seeds • Common types • Achene • Samara • Grain • Nut

  17. ACHENES One-seeded fruit Pericarp free from the seed Sunflower “seeds” SAMARAS Winged achenes Dispersed by wind Fruit in maple trees and ash trees

  18. Grains • Also called caryopsis • Single seeded fruits • Pericarp fused to seed coat • Fruits of all cereal grasses: wheat, rice, corn and barley

  19. Wheat grain Fused seed coat and ovary wall layers

  20. Nuts • One-seeded fruits • Hard stony pericarps • Hazelnuts, chestnuts, and acorns • Other things commonly called nuts that are not true nuts but are actually seeds

  21. 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

  22. Raspberries and Blackberries

  23. Aggregate-Accessory Fruit • Strawberries also contain accessory tissue • Seeds on the surface are actually separate achenes on enlarged, fleshy receptacle

  24. Fruit Types III: 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

  25. Seed Structure and Germination

  26. 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 valuable foods

  27. 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

  28. Dicot seed • Cotyledons attached to and enclose the embryonic plant • Cotyledons occupy the greatest part of the seed • Cotyledons have absorbed the nutrients from the endosperm which may be entirely used up

  29. Dicot seed - Lima bean • Thin seed coat • 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

  30. 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 root) • Radicle - the embryonic root

  31. Monocot seed • Cotyledon transfers food from the endosperm to the embryo • In several monocot families large amounts of endosperm are present

  32. 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

  33. Seed germination • Absorption of water • Emergence of the radicle • Shoot emerges: • 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

  34. Tomatoes • Native to Andes Mts in South America • First cultivated in Mexico • Spanish Conquistadors introduced tomatoes to Europe in the 16th century

  35. What is in a name? • Name among native peoples in Mexico was tomatl • In Europe there were lots of names for this fruit - love apple or pomme d’amour was the French name • Scientific name Lycopersicum esculentum (meaning edible wolf peach)

  36. Poisonous Relatives • Member of the family Solanaceae (called the potato or tomato family) • Family known for its poisonous plants • Also called the nightshade family because of deadly nightshade and henbane • Also called tobacco family

  37. Suspect Plant • Because of the poisonous relatives, tomatoes were suspected by many as poisonous • Hard reputation to live down • In 1820 Col. Robert Johnson ate a bushel of tomatoes in front of a crowd to prove they were safe

  38. Popular “vegetable” • Although botanically it is simple fleshy fruit (a berry), in 1893 the Supreme Court ruled it was a vegetable • Widely used in fresh, canned, dried, pickled, and processed varieties • Also a favorite experimental tool - used in space shuttle, genetic engineering, and cloning experiments

  39. Apples - Malus pumila • Family Rosaceae • Long history of use • One of the first trees cultivated • Native to Caucasus Mts of western Asia • Many legends associated with apples

  40. Apple Varieties • Pome - simple accessory fruit • Hundreds of varieties exist but only a few dominate the market • Delicious, Rome, Gala, McIntosh • Most apple trees are produced by grafting rather than by seeds • Grafting creates thousands of identical copies with the desired traits

  41. Citrus Fruits

  42. 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

  43. 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

  44. 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)

  45. Pummelos

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