Structure and Function of Flowering Plants.pdf

Flower is a specialized shoot with modified leaves...

Flower is a specialized shoot with modified leaves Pedicel (stalk) supports the flower, some flowers are sessile (without stalk) Parts of a Bisexual Flower Receptacle (thalamus) at the tip of the pedicel where floral parts are borne Four whorls of floral parts: sepals, petals, stamens, and carpels Complete (perfect) flower has all four whorls of floral parts Complete and Incomplete Flowers Incomplete (imperfect) flower is missing one or more sets of floral whorls Essential parts are the reproductive organs: stamens (male) and carpels (female) Flower Structure Essential and Non-essential Floral Parts Non-essential (accessory) parts are the sepals and petals that protect or attract pollinators Sepals and petals may be similar in appearance, forming a perianth Perianth can be sepaloid (green) or Perianth and Bracts petaloid (colored) Bracts are leaf-like structures that may be green or colored, sometimes mistaken for petals Nectar-secreting glands that attract insects for pollination Nectaries Prominent nectaries found in some flowers like Nasturtium Bisexual (perfect) flowers have both male (stamens) and female (carpels) parts Unisexual (imperfect) flowers have only Male, Female, and Bisexual Flowers male or female parts Neuter flowers lack both male and female reproductive organs Sexuality in Flowers Monoecious plants have separate male and female flowers on the same individual Monoecious and Dioecious Plants Dioecious plants have male and female flowers on different individuals Usually 5 sepals, may be free Structure and (polysepalous) or fused (gamosepalous) Function of Calyx (Sepals) Protect the young flower bud and can be Flowering Plants green or brightly colored (petaloid) Typically arranged in a single whorl, may be free (polypetalous) or fused (gamopetalous) Corolla (Petals) Attract insects for pollination and protect the reproductive parts Variable number of stamens, each with a Floral Parts: Detailed Description filament and bilobed anther Stamens may be free (polyandrous) or Androecium (Stamens) joined in groups (monadelphous, diadelphous, polyadelphous) Pollen grains produced in the anther sacs Composed of one or more carpels, each with a stigma, style, and ovary Stigma receives pollen, style connects to Gynoecium (Carpels) the ovary containing the ovules Placenta attaches the ovules to the ovary wall Arrangement of flowers on the plant axis Inflorescence Flowers may be solitary or clustered in various patterns Inflorescence and Placentation Arrangement of ovules within the ovary Placentation Different patterns observed in fruits like pea, tomato, mango, etc.