In orchids each of the pollen-masses has a prolongation or stalk (caudicle) which adheres to a prolongation at the base of the anther (rostellum) by means of a viscid gland (retinaculum) which is either naked or covered.
The filament is usually of sufficient solidity to support the anther in an erect position; but sometimes, as in grasses, and other wind-pollinated flowers, it is very delicate and hair-like, so that the anther is pendulous (fig.
The anther consists of lobes containing the minute powdery pollen grains, which, when mature, are discharged by a fissure or opening of some sort.
When the anther lobes are rendered horizontal by the enlargement of the connective, then what is really longitudinal dehiscence may appear to be transverse.
The endothecium varies in thickness, generally becoming thinner towards the part where the anther opens, and there disappears entirely.
The anther entire (a) with its filament; section of anther (b) showing the four loculi.
The pollen-grains or microspores contained in the anther consist of small cells, which are developed in the large thick-walled mother-cells formed in the interior of the pollen-sacs (microsporangia) of the young anther.
The Monandreae have been subdivided into twenty-eight tribes, the characters of which are based on the structure of the anther and pollinia, the nature of the inflorescence, whether terminal or lateral, the vernation of the leaf and the presence or absence of a joint between blade and sheath, and the nature of the stem.
In the young state there are usually four pollen-sacs, two for each anther-lobe, and when these remain permanently complete it is a quadrilocular or tetrathecal anther (fig.
The walls of the cells are frequently absorbed, so that when the anther attains maturity the fibres are alone left, and these by their elasticity assist in discharging the pollen.