184 



MISSOURI BOTANICAL GARDEN. 



filaments may be naked or provided with hairs. Thus, 

 excepting the character of dehiscence, with perhaps a slight 

 elongation of the anthers, the flowers of the two forms 

 treated here do not differ widely from the other genera of 

 . the family. In floral structure, the most highly organized 

 member is Cochliostema, to be discussed later. 



Pontedcriaceae. 



Monochoria (3 species, 1 in tropical East Asia, 1 in 

 tropical and subtropical Asia and East Africa, and 1 in 

 Australia), of the Pontederiaceae, has the corolla and the 

 form of the anthers of this type. The filaments are not so 

 reduced in length as is generally the case, and the terminal 

 pores are soon continued down the sides in longitudinal 

 slits. 



A comparison of the disposition and form 

 in their relation to the length and form of the perianth 

 tube in the other genera of this family is interesting. In 

 Heteranthera the perianth tube may be very long and nar- 

 row, but the limb is widely patent. In the other genera, 

 the perianth is more widely expanded from the base but 

 still shows a tube of considerable length. Only in Monoch- 

 oria is the tube wanting and the elements of the perianth, 

 which are almost free to the base, widely patent. Con- 

 cerning the form of the stamens it may be said that in 

 Eichornia, Pontederia and 



b 



R 



morphic androecium is characterized by filaments of con- 

 siderable length with basifixed or nearly basifixed and short, 



thick anthers which 



d 



In Heteranthera the anthers are sometimes more elongate, 

 approaching linear in form. The filaments, inserted at the 

 top of the corolla tube, may be of the same length as the 

 anthers or much longer. In Monochoria, the filiform fila- 

 ments are of about the same length as the anthers, which 

 seem to be the most elongate in the family, and, perhaps, 

 with walls of firmer texture. 



