330 CLEISTOGAMIO PLOWEES. Chap. Vllt. 



togamic flowers ; the latter yield from 18 to 24, whilst 

 the former only from 8 to 10 seeds ; these two kinds of 

 flowers are produced simultaneously, whereas in several 

 other members of the family the cleistogamic ones 

 appear only during the hot season. According to 

 Torrey and G-ray, the North American species of He- 

 lianthemum, when growing in poor soil, produce only 

 cleistogamic flowers. The cleistogamic flowers of 

 Specularia perfoUata are highly remarkable, as they 

 are closed by a tympanum formed by the rudimen- 

 tary corolla, and without any trace of an opening. 

 The stamens vary from 3 to 5 in number, as do 

 the sepals.* The collecting hairs on the pistil, which 

 play so important a part in the fertilisation of the 

 perfect flowers are here quite absent. Sir J. Hooker 

 and Dr. Thomson state t that some of the Indian 

 species of Campanula produce two kinds of flowers ; 

 the smaller ones being borne on longer peduncles 

 with differently formed sepals, and producing a more 

 globose ovary. The flowers are closed by a tympanum 

 like that in Specularia. Some of the plants produce 

 both kinds of flowers, others only one kind ; both yield 

 an abundance of seeds. Professor Oliver adds that he 

 has seen flowers on Campanula oolorata in an intermedi- 

 ate condition between cleistogamic and perfect ones. 



The solitary almost sessile cleistogamic flowers pro- 

 duced by Monochoria vaginalis are differently protected 

 from those in any of the previous cases, namely within 

 " a short sack formed of the membranous spathe, with- 

 out any opening or fissure." There is only a single 



* Von Mohl, 'Bot. Zeitung/ of tlie perfect flower is mostly 



1863, pp. 314 and 323. Dr. Brom- 5-oleft. 



field (' Phytologist,' vol. iii. p. f 'Journal Linn. Soc' vol. ii. 



630) also remarks that the calyx 1857, p. 7. See also Professor 



of the cleistogamic flowers is Oliver in ' Nat. Hist. Eeview,' 



usually only 3-cleft, while that 1862, p. 240. 



