824 CLEISTOGAMIC FLOWERS. Chap. VIII 



flowers of the double yiolet have been rendered 

 double. 



Vandellia nummularifoKa. — Dr. Kuhn has collected* 

 all the notices with respect to cleistogamic flowers in 

 this genus, and has described from dried specimens 

 those produced by an Abyssinian species. Mr. Scott 

 sent me from Calcutta seeds of the above common 

 Indian weed, from which many plants were success- 

 ively raised during several years. The cleistogamic 

 flowers are very small, being when fully mature under 

 ■^ of an inch (1 • 27 mm.) in length. The calyx does 

 not open, and within it the delicate transparent corolla 

 remains closely folded over the ovarium. There are 

 only two anthers instead of the normal number of four, 

 and their filaments adhere to the corolla. The cells of 

 the anthers diverge much at their lower ends and are 

 only j^-Q of an inch ( ■ 181 mm.) in their longer diameter. 

 They contain but few pollen-grains, and these emit 

 their tubes whilst still within the anther. The pistil 

 is very short, and is surmounted by a bilobed stigma. 

 As the ovary grows the two anthers together with the 

 shrivelled corolla, all attached by the dried pollen- 

 tubes to the stigma, are torn off and carried upwards 

 in the shape of a little cap. The perfect flowers gene- 

 rally appear before the cleistogamic, but sometimes 

 simultaneously with them. During one season a large 

 number of plants produced no perfect flowers. It has 

 been asserted that the latter never yield capsules ; but 

 this is a mistake, as they do so even when insects are 

 excluded. Fifteen capsules from cleistogamic flowers 

 on plants growing under favourable conditions con- 

 tained on an average 64*2 seeds, with a maximum of 

 87; whilst 20 capsules from plants growing much 



' Bot. Zeitung,' 18G7, p. 65. 



