380 ORCHIDACE^. 



The ovary is inferior and long, taking the place of 

 the pedicel which is as a rule absent. There are three 

 sepals and three petals, as is usual with monocotyledons, 

 but one of the petals is very different in shape from the 

 others, and generally has a bag-like depression at the 

 upper end, called a ' sac ' if it is shallow (t. 258), or a 

 'spur* if it is long (tt. 254, 256). 



This petal, known always as the lip or the labellum, is really the 

 uppermost or dorsal one and in a few orchids, e.g., satvrium (p. 405) stands 

 up at the back of the flower, but in most cases is brought by a twisting of 

 the ovary to the lower side and hangs down there. It is not usually 

 difficult to make this out by the twisting of the lines in the ovary (t. 251). 



For the explanation of the structure of the column reference must be 

 made to Darwin's British and Foreign Orchids or to any good text-book ; 

 it must suffice here to say thai, assuming the flower to be derived from the 

 usual monocotyledonous type of five whorls of three each, i.e., three sepals, 

 three petals, three outer stamens, three inner stamens and a three-celled 

 ovary, the column is considered to be made up of one stamen of the outer 

 whorl and two styles whose stigmas, fused into one, form the sticky hollow 

 on its face. The other five stamens are all aborted, unless perhaps two of 

 them are part of the column, e.g., when that is winged, and two more part 

 of the labellum when it has lateral lobes. The pollen of each half anther 

 is always aggregated into one, two or four waxy masses termed polliniums. 



The disposition of the two halves of the anther differs in 

 different orchids. In habenaria and its allies — such as the large 

 white Elephant's Head or Snowdrop orchid, the Purple-ground 

 orchid, the S\veet-Scented Pink Twin-spur, and the Butterfly, 

 Pyramid and Marsh orchids of England, — the two halves, 

 though close together at the top are separated at their bases and 

 attached to either side of the column. They open separately 

 by longitudinal slits to let out the polliniums. But in most 

 orchids, as .erides the Pink Rock orchid, and coelogyne 

 the Banana orchid, the two halves of the anther lie together on 

 top of the column and open by a cap which comes off as a 

 whole exposing the polliniums. In some of these orchids, e.g., 

 yERiDES, the anther-cap simply falls off at the slightest touch, in 

 others, e.g., ccelogyne, it remains attached by a filament (tt. 243, 

 247). The polliniums have slender stalks (caiidicies) ending in a 

 swelling or an elastic band which is or becomes attached to an 

 easily removed piece of the top edge of the column, called the 

 rostellum (t. 252). 



The two stigmas are usually combined as a slightly hollowed 

 sticky surface on the front of the column below the anther : in 

 Habenaria longicalcarata (t. 253) they project on either side as 

 curved green processes. 



