PLANTS WITH HIDDEN FLOWERS. 97 



while in the grasses they are often concealed 

 in the sheaths of the leaves. In one coun- 

 try a species may produce only cleistogamous 

 flowers, while in another country it may pro- 

 duce none. In some parts of Russia the 

 little toad-rush, or Juncus bufonius, pro- 

 duces no flowers but these hidden ones, but 

 I do not know that such flowers have been 

 observed on the plant in this country. The 

 common wild touch-me-not, Impatiens fulva, 

 has become naturalized in England, but it 

 seldom produces any other than cleistoga- 

 mous flowers there. The proportion of the 

 hidden to the ordinary showy flowers is about 

 20 to 1. Cleistogamous flowers were some- 

 what known before the time of Linnaeus, 

 and they occasioned warm discussion upon 

 the doctrine of sexes. 



Cleistogamous flowers are of benefit to the 

 plant in producing seeds economically. Be- 

 sides the saving in petals, stamens, pedun- 

 cles, and in the diminution of parts, there is 

 a very great saving of pollen. It is calcu- 

 lated that the average cleistogamous flower 

 of wood sorrel produces 400 pollen grains, 

 of touch-me-not, 250, and of the grass Leer- 

 sia, 210. Compare these numbers with 

 243,600 grains in a flower of fall dandelion 



