shown that in Habenaria (Ophrydoideae) the compound 
stigma is supported by three vascular strands and in those 
species where the dorsal stigma is aborted, the supporting 
strand is obliterated simultaneously. Vermeulen’s sug- 
gestion that the rostellum in Bonatea (Ophrydoideae) 
represents an elongation of the receptacle is hardly con- 
vincing, because of the appendicular nature of the col- 
umn. To derive the viscid gland from the rostellum as 
a separate organ, or as a modified stigma, and the pollinia 
from the anther poses a situation rather difficult to com- 
prehend. In my opinion, the whole structure of the pol- 
linium originates as a unit from the anther; the gland 
itself is a transportation mechanism only. Furthermore, 
the nature of the anther and the pollinia in the Ophry- 
doideae is such that self fertilization is hardly possible. In 
those few species which are known to be autogamous, 
the presence of the connective tissue (whether or not rep- 
resenting a rostellum in reality) does not prevent self 
fertilization. Much research must yet be done with re- 
spect to developmental anatomy before a final conclu- 
sion as to the origin of the rostellum and the viscid gland 
may be drawn. 
Indeed, at this point, it makes no difference which of 
the proposed theories is correct, because each of them 
bears out the same conclusion: the column of the Ophry- 
doideae is not derived from that of any of the other 
groups, but it is the product of an independent evolu- 
tionary line emerging from a polyphyletic complex. 
Pollen. The pollen grains in orchids, at the time of 
shedding, are either single or more commonly united into 
tetrads, with or without aggregation into pollimia. In 
A postasioideae and Cypripedioideae, as mentioned above, 
no pollinia are formed, but the suleate or monocolpate 
microspores (similar to other Monocotyledons, e.g. Hy- 
powis) are always single at maturity. 
[ 76 | 
