THE WELCOME OF THE FLOWERS 



373 



There is a species of Bitter-cress 

 ( Cardamine chenopodifolia) which 

 has cleistogamic flowers that burrow 

 into the earth. They spring from 

 underground runners or stalks, and 

 are produced earlier than the open 

 flowers, which are borne upon aerial 

 shoots. 

 Charles Dar- 

 w i 11 and 

 others have 

 asserted the 

 same thing of 

 the cleisto- 

 gamically 

 produced 

 " ito^'B I capsules 



FIG. 458. CLIMBING COB^EA (Cobcea scandens). 

 Section of flower in first stage of development ; and fruit. 



of the Violet ; 



but Professor 



Henslow, in 



his Origin of Floral Structures, appears to doubt 



the correctness of the observation. He explains 



that they cer- 



tainly are 

 " very, if not 

 more, fre- 

 quently, not 

 buried at all, 

 but only con- 

 cealed be- 

 neath the 

 foliage." 



In the 

 cleistogamic 

 flowers of the 

 C o m m o n 

 Wood-sorrel (Oxalis acetosella) the un- 

 opened corolla forms a sort of cap, 

 which may be removed entire, al- 

 though, in the flowers that open, the 

 petals do not cohere at all. 



The production of cleistogamic 

 flowers appears to depend upon 



FIG. 457. MORNING 

 GLORY (Ipomcea pur- 

 pur ea). 



(k) Calyx ; (c) corolla ; (*) sta- 

 mens ; (*<) stigma. 



FIG. 459. CLIMBING COB^EA. 

 Section of flower in third stage of development. 



