Question

What is the Polyadelphous condition?

Answer 1

Stamens are the male reproductive organs or microsporophylls of a flower. Each stamen has three parts: filament, connective and anther. Filament is stalk like. It is meant for raising the anther above the level of thalamus. Anther is bilobed. The two lobes of anther are attached to each other by a sterile tissue called connective. Because of the presence of two lobes, the anther is called bithecous. In members of family malvaceae (e.g., China Rose) anthers are single lobed and, therefore, called monothecous. Each anther lobe has two chambers or sacs. They contain pollen grains. Bithecous anthers are tetrasporangiate while monothecous anthers are bisporangiate.

Complete answer:
Stamens remaining within the Perianth are called inserted (e.g., Petunia, Salvia) while stamens protruding out of the perianth are called exserted (e.g., Acacia , Mimosa). Stamens forming a single whorl are known as haplostemonous. Individual stamens may be antisepalous or opposite the sepals and antipetalous or opposite the petals. Antisepalous stamens are generally alternipetalous while antipetalous stamens are alternisepalous. The term antiphyllous or alterniphyllous is used if distinction of sepals and petals is absent. In case the stamens are arranged in two whorls, the condition can be diplostemonous (outer alternipetalous, inner antipetalous, e.g., Cassia) or obdiplostemonous (outer antipetalous and inner alternipetalous, e.g., Dianthus). Stamens are polystemonous if they occur in more than two whorls, e.g., Acacia. Free stamens are called polyandrous. The term isostemonous is used for similar stamens and heterostemonous for stamens different in length, shape and dehiscence. Two types of heterostemonous and polyandrous stamens are didynamous (2 long. 2 short, e.g., Ocimum) and Tetradynamous (2 outer short, 4 inner long, e.g., Brassica).
Cohesion of stamen is of three types: Adelphous, syngenesious and synandrous.
1. Adelphous- Stamens are fused in the region of their filaments only. Depending upon the number of groups formed, it is of three types
(i) Monadelphous (Monoadelphous). Filaments of all stamens are fused to form a tube around the gynoecium. Anthers are free, e.g China Rose.
(ii) Diadelphous. There are two groups of stamens formed by fusion of their filaments. In Pea and other papilionaceous plants, nine stamens form an incomplete tube while the 10th stamen is free.
(iii) Polyadelphous: It is a condition where stamens are fused together with each other by their filaments to form multiple bundles in which anthers are set free, e.g., Citrus.

Note:
Syngenesious, All the stamens are fused by their anthers to form a tube around the style. Filaments are free, e.g., Sunflower and many other members of family asteraceae. Since the stamens are fused by the anthers only, the syngenesious condition is also called synantherous, Syngenesious or Synandrous. Stamens are fused in the region of both their filaments and anthers, e.g., Cucurbita , Luffia. Adhesion of stamens: Epipetalous- Stamens are attached to petals with no distinct connection with the thalamus, e.g., Solanum. Epiphyllous or Epipetalous- Stamens are attached to perianth lobes or tepals, e.g., Asphodelus. Gynandrous. Stamens are attached to gynoecium, e.g., Calotropis.