330 CLEISTOGAMIC FLOWERS. Chap. VIII. 



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 Gray, the North American species of He- 

 lianthemum, when growing in poor soil, produce only 

 cleistogamic flowers. The cleistogamic flowers of 

 Specularia perfoliaia are highly remarkable, as they 

 are closed by a tympanum formed by the rudi- 

 mentary corolla, and without any trace of an open- 

 ing. 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. Drs. 

 Hooker and 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 tym- 

 panum 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 coloraia 

 in an intermediate 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, 



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



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



field (' Phytologlst,' vol. iii. p. t 'Journal Linn. See' vol. ii. 



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



of the cleistogamic flowers is Oliver in ' Nat, Hist, Beview 



usually only 3-clcft, while that 1862, p. 2^0. 



