512 NAIADACEyT: 



leaves and unbranched peduncle, with 3 — 5 whorls, each of 3 — 5 

 rather large, delicate, white or pinkish -flowers, rising a few inches 

 out of the water. — Rivers and ditches ; not uncommon. — Fl. 

 July — September. Perennial. 



*5. heterophvlla, a North American species, with ovate unbarbed 

 leaves on long sheathing petioles and short peduncles with small 

 white flowers, resembling those of the Water-Plantains, occurs in 

 the Exe. 



3, Damasonium (Star-fruit, Thrumwort). — Aquatic plants with 

 the habit of the Water-Plantains ; but with floating leaves and 6 — 

 10 carpels united at their base and spreading horizontally in the 

 form of a star. (Name of uncertain origin.) 



I. D. Alisma (Common Star-fruit). — The only British species; 

 leaves long-stalked, cordate-oblong, 3 — 5-ribbed, floating ; -flowers 

 in I — 3 whorls, stalked, white, \ in. across, with a yellow spot at 

 the base of each petal ; fruit generally of 6 rather large, 2-seeded, 

 long-beaked, dehiscent carpds. Gravelly ponds and ditches in 

 the south; rare. — Fl. June, July. Perennial. 



4. BuTOMUS (Flowering Rush), represented only by one species, 

 B. umbelldtus, is a tall aquatic with a creeping rhizome ; sword- 

 shaped, radical leaves 2 — 4 feet long ; and numerous handsome, 

 rose-coloured flowers, i in. across, in a terminal, bracteate, 

 simple umbel, on a cylindric peduncle 2 — 3 feet high ; the 

 perianth-leaves are all petaloid ; stamens 9, with red anthers ; 

 carpels 6, united at the base, many-seeded, dehiscent down one 

 side. — Stagnant water and slow rivers ; not uncommon. (Name 

 from the Greek bous, an ox, and temno, I cut ; because cattle 

 were apt to cut their mouths with the leaves of some plant to 

 which the name was originally applied.)- -Fl. June, July. 

 Perennial. 



Ord. LXXXVIII. Nai adages. — Pond-weed Family 



A small Order of aquatic and marsh plants, usually with a 

 creeping rJdzome ; slender, branched, jointed stems ; leaves 

 sheathing at the base, often floating, sometimes almost leathery, 

 but more frequently thin and pellucid ; flowers smaM, inconspicu- 

 ous, olive-green, sometimes solitary, but more frequently in spikes ; 

 perianth of 3 — 6 inferior, valvate scales, tubular, or absent ; 

 stamens i — 6, hypogynous ; carpels 1 — 6, i-ovuled, indehiscent, 

 sometimes in distinct flowers from the stamens. 



I. Triglochin. — Leaves linear; flowers ebracteate, perfect; 

 perianth of 6 similar, erect, green leaves ; stamens 6 ; carpels 3 — 6. 



