Flower - A fascinating structure of Flowering plant

• Flower is a special reproductive strcuture found in Angiospermic plants. It develops in the axil of a small  leaf-like structure called bract.

• If a flower bears bract then it is called bracteate or it is absent called ebracteate. The stalk of a flower is called a pedicel.

• A pedicel bearing flower is called a pedicellate. If the pedicel is small the flower is sub sessile and if the pedicel is absent then the flower is sessile.

Essential and Non essential organ in flower 

• The tip of the pedicel has a swollen structure called thalamus or receptacle. It bears calyx , corolla, androecium and Gynoecium. 

• Out of these androecium and Gynoecium are essential organs because they take part in reproduction.

• Calyx and corolla are not take part directly in reproduction so they are a non essential organ of the flower and are called as accessory reproductive organ.

• In some flowers like waterlily, calyx and corolla are not distinct. It is called as Perianth.

Complete and Incomplete flower 

• A complete flower has all four types of floral organ.

• If any floral organ like sepals or petals or stamens or carpels is absent . Then the flower is said to be incomplete . 

Staminate and pistllate  flower 

• If a flower has both essential organs then it is perfect. A perfect flower may be hermaphrodite or bisexual.

• If a flower has only one type of essential organ it is called  unisexual or imperfect.

• A flower is staminate when only stamen is present and flower is pistillate when only pistil is present.

• The flower is neuter if all essential organs are absent or non functional.

Monocious and Diocious flower

• A unisexual flower may be male or female. If male  and female flowers are present on the same plant  then the plant is Monoecious.

• if male and female plants are present on a different plant than the plant is said to be Dioecious. Castor, Maize cucurbits are monoecious plants whereas Papaya Date palm are Dioecious.

Remember 👌🏽👌🏽A plant that has more than two types of flower like bisexual or unisexual such plants are called Polygamous like Mango.

Isomery in Flower

• Isomery is a condition in which a flower has the same basic number of parts in different floral organs.

• A flower is bimarous like Mustard whereas onion is an example of trimerous.

• A flower with different basic number of parts called heteromerous. Solanum nigrum is an example of heteromarous because it has five sepals, five petals, five stamen and two carpal.

Floral Phyllotaxy 

• The arrangement of different floral organs on the thalamus is called floral phyllotaxy.

• When all floral organs are developed spirally, called spiral phyllotaxy in Magnolia.

• In Mustard Onion Cyclic phyllotaxy is seen because floral organs are borne in a whorl. 

• An intermediate condition  found in Ranunculus in which some floral organs are borne spirally and some borne in whorl, called Spirocyclic.

Floral symmetry

• The arrangement of different floral organs around the axis of the flower.

• The axis of the stem on which the flower is developed is called the mother axis.

• If a flower is divided into two equal radial halves by any radial plane passing through the center then the flower is radial symmetrical or Actinomorphic like Mustard, Datura, Solanum.

• If a flower is divided into two equal vertical halves by only a single  vertical plane passing through the center then the flower is  bilateral symmetrical or Zygomorphic like Pea Bean Cassia .

• A flower is asymmetrical if it can not be divided into two equal halves like Canna Opuntia. This flower is irregular or asymmetrical .

Regular and irregular flower

• If a flower is said to regular if there is no difference in shape size color and origin in member of each type of floral organ like Mustard.

• If a flower is said to irregular if there is any difference in shape size color and origin in member of each type of floral organ. 

• A flower cane be trimerous, tetramerous pentamerous if floral appendages are present in multiple of 3, 4 and 5 respectively.