The following technical terms are used in connection with the description of flower.
Description of a flower
The following technical terms are used in connection with the description of flower.
1. Floral whorls
Complete: When all the four whorls. (Calyx, Corolla, Androecium, and Gynoecium) are present in a flower, it is termed complete. Incomplete: When one or more whorls are absent the flower is described incomplete. a. Monochlamydeous: Some flowers have only one accessory whorl and they are called Monochlamydeous. b. Dichlamydeous: Normally flowers have two outer whorls which are usually differentiated into calyx and corolla. Such flowers are known as dichlamydeous. c. Achlamydeous: There are a number plants, where the flowers have neither calyx nor corolla. Such flowers are described naked or achlamydeous.
2. Sex distribution
Bisexual or Perfect: When both the essential whorls i.e., androecium and gynoecium are present in a flower, it is called bisexual or perfect.
Unisexual or imperfect: A flower having only one of the essential whorls is called unisexual or imperfect. The unisexual flowers may be of two types.
Staminate. Male flower with androecium, only
Pistillate. Female flower with gynoecium only
Monoecious
If male and female flowers develop in the same plant, it is called Monoecious eg. Coconut, Maize etc.
Dioecious
If male and female flowers are borne on separate plants, it is termed dioecious eg. Palmyrah palm, Papaya, Mulberry etc.
Polygamous If a plant develops three kinds of flowers i.e. staminate, pistillate and bisexual flowers, it is called polygamous. eg. Mango, Cashewnut etc. 3. Floral Symmetry
The shape, size and arrangement of floral appendages (i.e. Calyx, corolla, androecium and gynoecium) around the axis of a flower is called floral symmetry. The axis to which the flower is attached is called mother axis. The side of flower towards mother axis is called posterior side and the side away from it is called anterior side. On the basis of floral symmetry there may be following three conditions of a flower. Actinomorphic: A flower with radial symmetry, i.e., the parts of each whorl are similar in size and shape. The flower can be divided into two equal halves along more than one median longitudinal plane, eg. Hibiscus, Solanum, etc. Zygomorphic: A flower with bilateral symmetry, i.e. the parts of one or more whorls are dissimilar. The flower can be divided into two equal halves in only one vertical plane, eg. Pisum Asymmetric: A flower which cannot be divided into two equal halves along any vertical plane, eg. Canna Arrangement of floral organs
Cyclic: The floral parts are arranged in definite whorls around the axis of flower, eg. Brassica, Solanum etc. Acyclic: The floral parts are arranged in spirals and not in whorls, eg. Magnolia Spirocyclic: Some of the floral parts are in whorls and others in spirals (Hemicyclic), eg. Rose, Ranunculus, etc. Number of floral parts
Occurrence of the same number of floral parts in different floral whorls of a flower is called isomery. Sometimes, flowers have different number of parts in each whorl. This condition is called heteromerous. The isomerous flowers may be of the following types:-i. Dimerous : Floral parts in two's or multiplies of twoii. Trimerous : Floral parts in three's or multiples of threeiii. Tetramerous : Floral parts in four's or multiples of fouriv.Pentamerous : Floral parts in five's or multiples of five Dicotyledonous flowers are usually tetra, or pentamerous whereas monocotyledonous flowers are trimerous or multiples of three.
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11th 12th standard bio Biotany Plant Tree higher secondary school : Description of a flower |