The rostellum in orchids is the organ that forms the viscid liquid which makes it possible for the pollinia to stick to the bodies of visiting insects. The pollinia are then taken along and may be deposited wholly or partly on the stigma of another flower. The rostellum, however, does not occur in all orchids, viz. not in the Cypripedioideae (Diandrae), which do not possess pollinia. It is present in practically all the Orchioideae (Monandrae), on the other hand, but often has very different structures. In the group including Ophrys, Platanthera, Habenaria etc., it forms the viscid discs (viscidia), and in the other groups it usually consists of one single gland (viscidium), such as in Goodyera, Spiranthes and Epidendrum, whereas the simple gland, as we find it in Vanda and related genera, is moreover, characterized by a stipes, i.e. a tissue tape of the column formin ghe connection between the viscid disc and the pollinia.