mare's-tail family 183 



3. Callitriche (Water StarwortJ. — -Slender, submerged, 

 aquatic plants ; leaves exstipulate, opposite, simple, entire, the 

 upper ones sometimes floating and often for ming a rosette ; 

 flowers axillary, solitary, minute, monoecious, without calyx or 

 corolla, but usually with 2 white brads beneath, consisting either 

 of one stamen, or very rarely two, with a slender filament and a 

 one-chambered anther dehiscing transversely, or of a 4-angled, 

 4-chambered ovary, with 2 slender styles ; fruit of 4-winged, 1- 

 seeded, indehiscent cocci. (Name from the Greek kalos, beautiful, 

 ihrix, hair.) 



1 . C. paliislris (Spring Water Starwort). — Stems long, slender, 

 sending out long thread-like silvery roots from the joints ; the 

 upper leaves ovate-spathulate, floating in a light-green star-like 



calli'trich£ I'Alustris {Spring Water Starwort). 



rosette, the stamens being the only parts of the plant actually above 

 water ; bracts straight, deciduous ; styles erect ; fruit sessile, with 

 carpels swollen and bluntly keeled at the back. — Ponds and slow 

 streams ; common. — Fl. April — October. Annual or perennial. 



2. C. stagndlis (Spring Water Starwort). — A terrestrial form, 

 with the upper leaves broad roundish, in a close rosette, or absent ; 

 bracts sickle-shaped, persistent ; styles erect in flower, reflexed in 

 fruit ; carpels flattish, winged. — Chiefly on mud ; common. — Fl. 

 May — September. Annual or perennial. 



3. C. polymbrpha, as yet only recognised in a few localities, is 

 similar, its bracts being persistent ; but has stigmas 2 — 4 times as* 

 long as the ripe fruit, and carpels scarcely winged. 



4. C. hamuldta, usually very small ; leaves mostly inear ; 

 bracts sickle-shaped, deciduous ; styles long, diverging ; carpels 



