271 



The Water Starwort Family. 



(Callitrichace^). 



Annual or perennial floating plants, having opposite or 

 whorled leaves, and inconspicuous achlamydeous flowers. 

 They grow in all parts of the globe in deep or shallow water, 

 and comprise two species, both found in this country. Calli- 

 triche aquatica abounds in ditches and canals, its leaves 

 floating on the surface in the form of rays ; hence its name 

 Starwort. Hornwort (^Ceratophyllum demersum), has long, 

 slender floating stems, with whorled forked leaves. By 

 some botanists these two plants are considered as types of 

 distinct families, but by others they are placed in one. 



Division 3. — Diehlamyds. 



Flowers bisexual (generally), some unisexual furnished with 

 calyx and corolla, which are seated below the ovary (inferior) 

 or on its apex (^superior). Corolla monopetalous or polypeta- 

 lous, separate and free, or attached to the calyx. Stamens 

 hypogynous or epigynous, or seated on the calyx or corolla, 

 perigynous. 



The corolla being monopetalous or polypetalous, and with 

 the calyx seated above or below the ovary, admits of arrang- 

 ing the families of this division as follows. 



Section 1. — Corolla monopetalous. 



* Calyx and corolla inferior. 

 ** Calyx and corolla superior. 



Section 2. — Corolla polypetalous. 



* Calyx and corolla superior. 



** Calyx inferior, with the corolla attached. 

 *** Calyx and corolla inferior, separate. 



The principal exceptions to the above characters are in 

 the Begonia and Gourd Families being unisexual, as also in 

 some monopetalous corollas being so deeply cleft as to appear 



