jii.] PONTEDERIACEM. 315 



the movement of currents of viscid protoplasm may be 

 observed under a high magnifying power : the minute em- 

 bryo embedded in a cavity at one side of the albumen. 



Very few species of this widely dispersed (but not large) 

 tropical or sub-tropical Family are turned to any account. 



105. Natural Order, Eriocaulonece. — The Pipewort Family. 



Aquatic or marsh herbs. Flowers minute, unisexual, in 



terminal heads. 



Type — Eriocaulon sexangiilare (or E. quinqtieangulare). 



A small aquatic herb of rice-fields and wet places, with, 

 narrow, grass-like leaves, and small, involucrate heads of 

 minute monoecious flowers. 



Eriocaulon is the only large natural genus of the Family. 

 It is very widely spread in both hemispheres, though par- 

 ticularly abundant in South America. The excessively 

 minute flowers are arranged, like the florets of Compositae, 

 in terminal heads, borne by slender scapes. 



Very iQ\w species are made use of by man. 



106. Natural Order, Pontederiacecs. — The Pontederia 

 Family. 



Aquatic herbs. Flowers petaloid, racemose, from the 

 sheath of the last, or only leaf, of the scape. 



