56 



Thelymitka antennifeea, Hook, f . PL viii.A. 



The flower of this species is sweet smelling, yellow in 

 colour, and is provided with two very conspicuous reddish- 

 brown lateral appendages to the column, which stand up like 

 a pair of ears. These, together with the projecting, blunt 

 anther-point, give the column a singularly bat-like appearance. 

 Unlike many other Thelymitras, the flowers open freely in sun- 

 shine. The various stages in the mechanism of pollination 

 are represented in pi. viii.A, figs. 1 to 5. 



If a fairly early bud be examined (fig. 1) the column will 

 be found to be comparatively narrow, the anther-point broad, 

 smooth, and emarginate. The wings of the column (lu) are 

 imperfectly developed, the rostellum very prominent and situ- 

 ated in a notch in the upper border of the stigma. At this 

 period of development the pollen-cases (p c) are situated ver- 

 tically, and the pollinia at their lower narrow ends are in close 

 contact with the rostellum. 



A little later (fig. 2) a certain degree of obliquity has 

 become apparent in the pollen-cases, owing to the lateral 

 growth of the column forcing their upper and wider ends 

 apart, while the lower ends still remain united. The wings of 

 the column have become broader, the stigma has deepened, 

 and its edges have become more everted. The rostellum is now 

 very conspicuous and overhanging, and the column itself has 

 gained slightly in height as well as greatly in width. 



By the time the flower has become almost ready to expand 

 (fig. 3) oblique dehiscence has taken place in the pollen-cases, 

 the column has increased considerably in height, drawing up 

 these cases, thus causing an upward tugging by the pollinia 

 on the rostellum. The attachment of the pollen-masses to the 

 rostellum is now exposed and is seen to be almost direct, the 

 caudicle being virtually absent. The anther-point has become 

 roughened and has grown forward and curved downward, 

 thus tilting the lower ends of the pollen-cases backwards. As 

 the pollinia are being withdrawn from their cases by the up- 

 ward growth of the column this tilting movement forces their 

 upper ends further and further backwards (fig. 4) until the 

 masses at length lie in a horizontal plane. 



When expansion takes place (fig. 5) the antlier-point is 

 found to have grown still further forward and to have curved 

 still further downward. It has lost its greenish colour and has 

 become quite yellow and woolly. The growing forward of the 

 wings of the column and the deepening of the cup-like space 

 between them, together with the movements of the anther- 

 point, have increased the convexity of the back of the column 



