January, 1916.] 



THl': ORCHID WORLD. 



85 



petals are quite a subordinate feature of the 

 flower, but in many Oncidiums they are the 

 most conspicuous parts and much larger 

 than the labellum. The fringed petals of 

 Dendrobium Harveyanum are a remarkable 

 exception in this genus, and most probably 

 constitute a constant case of pelorism. 



The labellum is by far the most important 

 of the perianth segments, and it is also the 

 most polymorphous. But into whatever form 

 it has been moulded its structure is always 

 such as to secure the greatest efficiency m the 



Cattleya Boivringiana. 

 With labellum convolute over the column. 



part it performs as an aid to the fertilisation 

 of the flower. The labellum is usually 

 attached to the column by a short claw, which 

 is sometimes so delicately hinged on it that 

 the blade vibrates on the slightest force being 

 imparted to it, for instance, by a breath of air. 

 A remarkable case of this oscillatory motion 

 is afforded by the labellum of Bulbophyllum 

 barbigerum. In Epidendrum the claw is 

 more or less adnate to the column ; in 

 Odontoglossum it is simply parallel with it, 

 while m Oncidium and many other genera it 

 is at right angles to it. In Coryanthes and 

 Stanhopea the labellum is of a very complex 

 structure. In many Masdevallias it is 

 concealed within the sepaHne tube, and in 

 numerous other species, both of that and 



f 2 3 



Complex labellum of Stanhopea Wardii. 

 I , hypochile; 2, mesochile; 3, epichile. 



allied genera, it is an inconspicuous part of 

 the flower, while in many Oncidiums, and 

 especially m Miltonia, it is dilated into a 

 blade as large as, or larger than all the other 

 segments taken together. 



In many genera the labellum is prolonged 

 into a slender spur, which in Angraecum 

 sesquipedale, A. Ellisii, A. caudatum and 

 others attains a considerable length. In 

 other genera the spur is more open and takes 

 the form of a funnel, as in Vanda teres, 

 Dendrobium formosum, D. longicornu, or of 

 curved horn-like shape as in Aerides. Other 

 remarkable forms of the labellum occur m 

 Saccolabium, in which the basal part is 

 always hollowed out and extends downwards 

 like a small sac, hence the generic name ; in 

 Cypripedium where it appears like a large 

 slipper-like bag, and also in several species of 



Epidendrum pseudepidendrum, 

 With'claw of labellum adnate to the column, 



