4 ORCHIDS OF JAMAICA 



The form of the anther, its position on the column and the 

 means by which the pollen is transferred, vary widely in the 

 different genera. The anther contains two, four, or eight cells, 

 each of which contains a mass of pollen. The pollen masses 

 or pollinia are granular or powdery, breaking up into grains on 

 removal, as in Pogonia, Spiranthes, Vanilla, etc. ; or the grains 

 are united into packets by an elastic web as in Hahenaria ; or 

 waxy pollinia are produced by the formation of a strong common 

 covering round each mass as in Epidendrum and allied genera. 



The anther may stand erect and free on the top of the 

 column, as in Hahenaria where it is strongly united to the 

 rostellum by its base, and does not separate from the column when 

 the pollinia are removed. Usually, however, the anther is 

 attached to the rostellum by its apex. In this case it may be 

 erect and stand behind the stigma in such a way that the rostellum 

 reaches its apex, as in Stenorrhyncos, and the filament is gener- 

 ally thin but strong enough to hold the anther in place after 

 removal of the pollen. In most cases, however, the anther is 

 not erect, but is placed horizontally or hangs on the inner face of 

 the column ; it usually separates so easily from the thin filament 

 that it falls when the pollen is removed. It lies along the 

 rostellum or is more or less enclosed within a special cavity 

 of it (clinandrium), or is in contact with it only at the apex. 



The removal of the pollinia is generally effected by the help 

 of insects, which visit the flower for the sake of a sweet juice 

 contained in the sac or spur-like development or in the various 

 excrescences of the lip. Insects are attracted by the colour, form 

 and smell of the flower, the lip of which often forms an effective 

 landing-stage. The pollinia and stigma are so placed in reference 

 to the position assumed by the insect as to favour the carrying 

 off of the pollinia from one flower and its deposition upon the 

 stigma of another of the same species. 



To ensure its transference the pollinia are often attached to 

 a stalk, which is associated with a sticky mass, the so-called 

 " gland." Thus in Hahenaria each anther-cell is produced into 

 a long process {anther-canal), the contents of which form stalks 

 (caudicles), to which are attached above the numerous packets 

 of grains forming the pollinia. Below, the caudicle is attached 

 to a gland formed from the rostellum. The anthers split open 

 longitudinally when mature, and the pollinia are drawn out by 

 the adhesion of the gland to the head or proboscis of an insect 

 visiting the flower. In other genera no definite gland is pro- 

 duced from the rostellum, but a quantity of viscid matter exudes 

 from it when touched, and serves to glue the protruding tips of 

 the caudicles to the retreating object. In many genera the 

 pollinia are connected to the rostellar gland by a stalk (stipes or 

 pedicel), which is not a development of the anther, but of the 



