CHAP. VIII. CLEISTOGAMIC FLOWERS. 331 



without any opening or fissure." There is only a 

 single fertile stamen; the style is almost obsolete, 

 with the three stigmatic surfaces directed to one side. 

 Both the perfect and cleistogamic flowers produce 

 seeds.* 



' The cleistogamic flowers on some of the Mai- 

 pighiaceae seem to be more profoundly modified than 

 those in any of the foregoing genera. According to 

 A. de Jiissieuf they are differently situated from the 

 perfect flowers ; they contain only a single stamen, 

 instead of 5 or 6 ; and it is a strange fact that this 

 particular stamen is not developed in the perfect 

 flowers of the same species. The style is absent or 

 rudimentary ; and there are only two ovaries instead 

 of three. Thus these degraded flowers, as Jussieu 

 remarks, " laugh at our classifications, for the greater 

 number of the characters proper to the species, to the 

 genus, to the family, to the class disappear." I may 

 add that their calyces are not glandular, and as, 

 according to Kerner,| the fluid secreted by such 

 glands generally serves to protect the flowers from 

 crawling insects, which steal the nectar without aiding 

 in their cross-fertilisation, the deficiency of the glands 

 in the cleistogamic flowers of these plants may perhaps 

 be accounted for by their not requiring any such 

 protection. 



As the Asclepiadous 'genus Stapelia is said to pro- 

 duce cleistogamic flowers, the following case may be 

 worth giving. I have never heard of the perfect flowers 

 of Hoya carnosa setting seeds in this country, but some 

 capsules were produced in Mr. Farrer's hot-house ; 



* Dr. Kirk, ' Jnurn. Linn. Soc. J 'DieSchutzmittelderBliithen 



vol. viii. 18G4, p. 147. g^gen unbcrufonc Gasto,' 187C 



f ' Archives du Museum,' torn. p. 25. 

 iii 1 843, pp. 35-38, 82-8G, 58'J , 598. 



