1886-87.] the Scottish Alpine Botanical Club. 73 



returned to their several homes, and thus the excursion of 

 1886 came to a close, an excursion which will long be re- 

 membered as one of the most delightful and certainly one of 

 the most productive in the history of the Club. 



On the Dimorphism of the Flmvcrs of Wachendorfia paniculata. 

 By John Wilson, B.Sc, University of St Andrews. 

 (Plate I.) 



(Read 9th December 1886.) 



The inflorescence of this Wachendorfia (as exemplified by 

 the plants experimented with) is a raceme of from seven to 

 eleven scorpioid cymes, each cyme bearing usually four or 

 five flowers. Each flower lasts one day only, its duration 

 depending on the amount of sunshine. On many days they 

 may not be fully open more than six hours. They open 

 rapidly, and become degenerated as rapidly, those studied 

 during the beginning of June being closed and crumpled at 

 6 P.M. They are faintly scented. The perianth segments are 

 much alike in size and shape. What, for convenience, may 

 be called the uppermost outer segment (PL I. fig. 2, us), is of 

 a general dull orange. All the other segments are very pale 

 yellow, with a touch of orange at the apex, and a central line 

 of the same colour. There is a crescentic band of orange in 

 the centre of the flower, passing over the three upper segments. 

 As to the disposition of the perianth segments seen in front 

 view, the uppermost outer segment is vertical in position, and 

 the other two horizontal. The upper inner segments stand 

 at an angle of about 45°, and the lower one (PI. I. fig. 2, Is) 

 is vertical. In profile the latter is seen to be capable of 

 affording a lighting place for insects. There are two honey- 

 glands, situated in the angles between the bases of the upper 

 outer segment and the adjacent inner segments. They open 

 at the back of the flower by lenticular apertures formed by 

 the eversion of a small portion of the margin of the segments 

 bounding the glands (PI. I. fig. 4, gl). The secreting portion 

 is at the outer extremity of the glands. While quite exposed 

 from behind, they are approachable from the front of the 

 flower by two small orifices (PI. I. fig. 2, o). Secretion, 

 curiously enough, takes place the afternoon before the flower 



