38 Isabel G. Cookson : Floral Abnormalities. 



a small cylindrical outgrowth, which is fused with the petal-like- 

 structure for about half its length, the remaining portion being 

 free. Two perfect labella are present, alternating with the median 

 portion of the compound perianth segment. 



The interpretation is that the median lip is here replaced by a 

 flat petal, which has become fused with the two lateral sepals 

 to form a single anterior compound lobe S 2 +S s +P 8 . The evi- 

 dence for this conversion of the lip to a flat petal, is firstly the 

 presence of three notches at the apex of the compound segment, 

 the median one of which suggests the anterior petal, and secondly 

 the presence of a rudimentary appendage, attached to the middle 

 region. If this view is taken, the two labella which alternate 

 with the median segment are in the position of the two lateral 

 stamens of the outer whorl. 



EXPLANATION OF PLATE III. 



Fig. 1. — Shoot of E. obovalis. showing abnormal flowers. 

 2. — An abnormal flower, slightly enlarged. 

 3. — A normal flower, enlarged x 5. 



4. — An extreme type of abnormal flower, in which the* 

 petals are almost reduced to the condition of sta- 

 mens, x 5. 

 „ 5. — Transverse section of petal bearing a quadrilocular anther.. 

 Pollen grains and tapetal cells are shown. 



