POXn-WEKj;i FAMILY 



519 



perfect flowers without a pcriantk ; stamens 2 ; carpels 4, at first 

 sessile, afterwards each raised on a long stalk. (Named in honour 

 of H. B Ruppius, a botanist of the iSth century.) 



T. R. mariiima (Spiral Tassel Pond-weed). — A much-branched, 

 thread-like plant, with the habit of Potamogeton pechndlus, 2 feet 

 or more long ; leaves t — 3 in. long, with inflated sheaths ; flower- 

 stalk becoming spirally coiled, and 5 — 6 in. long, when in fruit; 

 ovate carpels with short beaks, on stalks, i — 2'in.long. — Brackish- 

 water ditches ; rare. — Fl. July — September. Perennial. 



2 . R . r u s i ell a I a 

 (Beaked Tassel Pond- 

 weed). — A more com- 

 mon form, differing in 

 the small, close sheaths 

 of its leaves, its short, 

 not spiral flower-stalk, 

 and the oblique base of 

 its carpels. — Fl. July, 

 August. Perennial. 



5. Zanniciielli.\ 

 (Horned Pondweed). — 

 Slender, submerged 

 plants, with linear leaves 

 with sheathing bases 

 and adherent stipules ; 

 minute, axillary, gener- 

 ally moncecious flowers 

 without a perianth ; 

 stamen, i ; carpels 2 — 6 ; 

 stigmas ■\pc\\.Siie. (Named 

 in honour of J. J. Zan- 

 nichclli, a Venetian 

 botanist.) 



1. Z. pah'istris (Commcjn Horned Pond-weed). — A submersed 

 aquatic with the habit of the preceding genus ; stem slender, 

 3 — 6 in. long, with spreading branches ; opposite, thread-like 

 leaves i — 3 in. long ; flowers axillary, sessile or nearly so ; stamen 

 ,\ — I in. long, with 4-chambered anther; carpels 2 — 4, sessile, 

 with short styles and small, crenulate sligmas. ^^Ihtches • common. 

 — Fl. May — August. Annual. 



2. Z. brachystemon, the commonest form, differs in having a 

 stamen only a quarter as long, \7ith a 2-chambered anther, and a 

 larger stigma. 



FLTPI.A MARiTIM;\ (Spiral Ti^sscl Pond-'n'cd). 



