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علوم گیاهی - Fruit 2

Fruit 2

شنبه 10 تیر 1391 04:59 ب.ظ

نویسنده : عسکر اله قلی
Fruit consists of carpels where the ovules (seeds) develop and the ovary wall or pericarp, which may be fleshy (as in apples) or dry and hard (as in an acorn). Some fruits have seeds (mature ovules) enclosed within the ovary (apples, peaches, oranges, squash and cucumbers). The peel of an orange, the pea pod, the sunflower shell, and the skin flesh and pit of a peach are all derived from the pericarp. Other fruit have seeds that are situated on the periphery of the pericarp (corncob, strawberry flesh).


Figure 1. In apples, the ovary wall becomes the fleshy part of the fruit. Notice the small fruit structure in the blossom.


Figure 2. Pome fruit (apple)


Figure 3. Stone fruit (peach)
Fruit Types

Conifers

Conifersare best known for their woody cones, pine cones. Junipers are an example of a conifer with a fleshy cone (Juniper berry). Upon close examination, the overlapping scales can be observed.

Figure 4. Fruit of conifers – Left: Woody seed cone (pine cone). Right: Fleshy seed cone (Juniper berry).
Flowering Plants (Angiosperms)

Depending on flower structure and inflorescence type, fruits may be either simple, aggregate, or multiple.

  • Simple – Fruit formed from one ovary.
  • Aggregate – Fruit formed from a single flower with many ovaries. If not all of the ovaries are pollinated and fertilized, the fruit will be misshapen (raspberry, magnolia).
  • Multiple – Fruit developed from a fusion of separate, independent flowers born on a single structure (mulberry, pineapple, beet seed).


Table 1. Key to Common Fruit Types
1a. Fruit fleshy. -- go to 21b. Fruit dry at maturity. -- go to 6
2a. Fruit simple, that is derived from a flower with a single ovary. -- go to 32b. Fruit derived from a single flower with many ovaries. – Aggregate Fruit(raspberry, magnolia). Note: If not all of the ovaries are pollinated and fertilized, the fur it will be misshapen.2c. Fruit develops form multiple separate flowers in an inflorescence, the fruits coalesce together to form a single “fruit” at maturity. – Multiple Fruit (mulberry, pineapple, beet seed)
3a. Fruit with a single seed enclosed in a hard pit. Theexocarp (outer layer) becomes the thin skin; the mesocarp(middle layer) becomes thick and fleshy; and the endocarp(inner layer) becomes a hard stony pit. – Drupe (peaches, olives, cherries, plums) 3b. Fruit with more than one seed, the seed not enclosed in a hard pit. -- go to 4
4a. Fruit develops from the ovary only. Pulpy fruit from one or more carpels that develops few to many seeds, inner and outer walls fleshy. – Berry (tomatoes, eggplant, blueberries, and grapes)
4a-1. Berries with a leather rind containing oils, enclosing a pulpy juice sack (carpels). –Hesperidium (citrus: oranges, lemons, limes, grapefruit)

4b. Fruits develops from the ovary plus other flower parts (accessory fruits). -- go to 5
5a. Simple fruits with relative hard rind at maturity, fleshy-watery interior with many seeds. – Pepos (cucumbers, melons, and squash)
5b. Simple fruit with several carpels and papery inner wall (endocarp) and fleshy outer wall. – Pomes (apple, pear, quince)
6a. Fruit not splitting at maturity. -- go to 76b. Fruit splitting open at maturity. -- go to 10
7a. One-seed achene fruit (elm, ash) or two-seed fruit (maple) with a wing-like structure formed from the ovary wall.–Samaras

7b. Fruit without wings. – go to 8
8a. One-seeded fruit with hard stony shell (pericarp) surrounding the seed. – Nut (oak, filbert, walnut)
8b. Fruit without hard shell. – go to 9
9a. Simple, one-seeded fruit with a thin seed coat (pericarp) surrounding and adhering tightly to the true seed. – Caryopsis(corn, rice, wheat, and barley)
9b. Simple, one-seeded, thin-wall fruit with seed loosely attached to ovary wall. – Achenes (sunflower)
10a. Fruit from two or more carpels, each with many seeds, splitting along or between carpel lines or forming a cap that comes off or a row of pores near the top. – Capsule (iris, poppy, jimson weed)
10b. Fruit splitting lengthwise along the edge. – go to 11
11a. Fruits from two carpels with a central partition to which the seeds are attached. Splits to expose seeds along central membrane. – Silique or Silicle(mustards)
11b. Fruits not leaving a central partition. – go to 12
12a. Fruit from a single carpel that splits along one suture only. –Follicles (Delphinium)
12b. Fruit from a single carpel usually splits along two sutures. Found in members of the Fabaceae (pea) family. – Legumes Pod (peas, beans)
12c. Fruit formed from two or more carpels that split at maturity to yield one-seeded halves. – Schizocarp



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