THE ANGIOSPERMAE 



'353 



Fig. 1260. — Streptocarpus princeps. A, Part of inflorescence with large, chas- 



mogamous and small, cleistogamous flowers. B, Chasmogamous flower, cut longi- 

 tudinally. C, Cleistogamous flower, cut longitudinally. D, Cleistogamous flower. 

 {After Engler.) 



cross-breeder, possessed between them all the genetical material for pro- 

 ducing an obligatory inbreeding race. 



The theory that cleistogenes are simply normal flowers inhibited in 

 development does not hold good for most of the Gramineae cited above, for 

 in them the cleistogenes are not part of the normal inflorescence, but are 

 isolated flowers, produced in the axils of the lower leaf-sheaths on flowering 

 shoots. They are produced after the maturity of the panicled spikelets and 

 the seeds they form are longer and narrower than those of the chasmogamous 

 flowers (Fig. 1261). It seems probable that they germinate in situ, being close 

 to the ground, and that they are a regular means of propagation. Stipa leuco- 

 tricha is an exception, however, for in addition to cleistogenes in the basal 



