Flowers and seeds

Plant Reproduction is the production of new individuals or offspring in plants, which can be accomplished by sexual or asexual reproduction.



Reproductive Flexibility of Flowering Plants

  • Angiosperms (flowering plants) are considered as one of the successful group of plants because they can reproduce both sexually and asexually .

  • Sexual reproduction entails the fusion of reproductive cells: eggs and sperm cells, collectively called gametes.

  • The union of gametes, which is called fertilization, occurs within the flower's ovary.

Sexual reproduction produces offspring by the fus of gametes, resulting in offspring genetically different from the parents.

  • Asexual Reproduction produces new individuals without the fusion of the gametes, genetically identical to the parent plants and each other, except when mutations occur.



FLOWER

  • A flower is a reproductive shoot usually consisting of four kinds of organs— sepals, petals, stamens, and carpels—arranged in whorls (circles) on the end of a flower stalk, or peduncle

  • The peduncle may terminate in a single flower or a cluster of flowers known as an inflorescence





TYPES OF FLOWER

Based on the Parts:

  • Complete Flower- all four parts are present

  • Incomplete Flower- lacks one or more of the parts.

Based on Sex:

  • Perfect Flower- both stamen and carpels

  • Imperfect Flower- has stamen or carpels but not both. (a) staminate or male flower; and (b) pistillate, also called carpellate and female flower.



PARTS OF FLOWER

  • Peduncle- the end of the flower stalk

  • Receptacle- the enlarged tip of the peduncle that bears some or all of the flower parts.

  • Sepal- one of the outermost parts of a flower, usual leaf- like in appearance, that protect the flower as a bud.

  • Calyx- the the collective term for all the sepals of a flower

  • Petal- one of the often conspicuously colored parts a flower attached inside the whorl of sepals.

  • Corolla- the collective term for all the petals of a flower.

  • Stamen- the pollen-producing part of a flower.

  • Filament- the thin stalk of a stamen

  • Anther- saclike structure on top of the stamen in which pollen grains form.

  • Carpel- the ovule-bearing reproductive unit of a flower.

  • Ovule- the structure in the ovary that develops into a seed after fertilization.

• A single carpel or a group of fused carpels is sometimes called a pistil.

• A pistil may consist of a single carpel (making it a simple pistil) or a group of fused carpels (making it a compound pistil)

  • Stigma- the sticky tip of a pistil where pollen grains land.

  • Style- a neck-like structure through which the pollen tube grows

  • Ovary- a jug-like structure that contains one or more ovules and can develop into a fruit

  •  Each ovule contains a female gametophyte, also known as an embryo sac, in which develops one female gamete (an egg) and two polar nuclei.

    • Superior ovary is one that has the other floral organs (sepals, petals, and stamens) free from the ovary and attached at the ovary's base.

    • Inferior ovary is one that is located below the point at which the other floral organs are attached.
      Fertilization- the Fusion of male and female gametes. After fertilization, flowering plants produce seeds inside fruits.

    • Pollination- In seed plants, the transfer of pollen grains from the anther to the stigma. Pollination happens before fertilization.

    • Self-Pollination- occurs within the same flower or within a different flower on the same individual plan amoycesa

    • Cross-Pollination- occurs when pollen grains are transferred to a flower on another individual of the same species.

    • Artificial Pollination- is the type of pollination carried out by humans. It is a mechanical technique used to pollinate plants when natural pollination is insufficient or undesirable.

The term coevolution describes such reciprocal adaptation, in which two species interact so closely that they become increasingly adapted to each other as each undergoes evolutionary change by natural selection.

• Some flowers produce nectar, a sugary solution, in special floral glands called nectaries.

  • ENDOSPERM. The nutritive tissue that is formed at some point in the development of all flowering plant seeds.

  • COTYLEDON. The seed leaf of a plant embryo that often contains food stored for germination.

  • Monocots have a single cotyledon, and eudicots have two.

  • The short portion of the embryonic shoot connecting the radicle to one or two cotyledons is the hypocotyl.

  • The shoot apex above the point of attach- ment of the cotyledon(s) is the plumule (also known as the epicotyl).

  • FRUIT In flowering plants, a mature, ripened ovary that often provides protection and dispersal for the enclosed seeds.

  1. SIMPLE FRUIT - fruit develops from one or several united carpels. At maturity, simple fruits may be fleshy or dry.

Berry (simple fruit)

  • A simple, fleshy fruit in which the fruit wall is soft throughout.

Pepo 

  • modified berry in which the fruit wall is a leathery rind.

Hesperidium 

  • leathery fruit wall with numerous oil glands

Examples: lemons, limes, oranges


Drupe (simple fruit)

  • A simple, fleshy fruit in which the inner wall of the fruit is a hard stone.

  • Peach (Prunus persica)

  • A drupe is a fleshy fruit with thin skin and a central stone containing the seed.

Examples: peaches, cherries, avocados, olives, and almonds

Follicle (simple fruit)

  • A simple, dry fruit that splits open along one suture to release its seeds; fruit is formed from an ovary that consists of a single carpel.

  • Milkweed (Asclepias syriaca)


Legume (simple fruit)

  • A simple, dry fruit that splits open along two sutures to release its seeds; fruit is formed from an ovary that Consists of a single carpel.

  • Green bean (Phaseolus vulgaris)

Examples: lima bean pods, pea


Capsule (simple fruit)

  • A simple, dry fruit that splits open along two or more sutures or pores to release its seeds; fruit is formed from ovary that consists of two or more carpels.

  • Iris (Iris)

Examples: iris, poppy, cotton


Caryopsis (simple fruit)

  • A simple, dry fruit in which the fruit wall is fused to the seed coat.

  • Wheat (Triticum)

Examples: corn kernel


Achene (simple fruit)

  • A simple, dry fruit in which the fruit wall is separate from the seed coat.

  • Sunflower (Helianthus annuus)


Nut (simple fruit)

  • A simple, dry fruit that has a stony wall, is usually large, and does not split open at maturity.

  • Oak (Quercus)

Examples: hazelnuts, acorns


  • AGGREGATE FRUIT - a fruit that develops from a single flower with several separate carpels that fuse, or grow together.

Examples: raspberries, blackberries (Rubus), magnolia

  • ULTIPLE FRUIT- a fruit that develops from the carpels of closely associated flowers that fuse, or grow together. A fruit that develops from the ovaries of a group of flowers.

Examples: pineapples, figs, mulberries 

(Morus)


  • ACCESSORY FRUIT- a fruit whose fleshy part is composed primarily of tissue other than the ovary.

Examples: strawberry, apples (Malus sylvestris), pears


  • American Apple - an Accessory fruit