794 



THE ALISMA PAMTLY. 



Perianth-segments all small and slightly coloured. Flowers 

 alternate, in a raceme or spike. 



Carpels 3, distinct. Stem leafy, rush-like 5. ScHEUCnzEitiA. 



Carpels 3, united till they ripen. Leaves linear, all 



radical 



6. Triglochin. 



I. BUTOME. BUTOMUS. 



A single species, distinguished from Alisma as a genus, or by some 

 botanists as an independent family, chiefly on account of the ovary, 

 which has several ovules in each carpel. 



1. Common Butome. Butomus umbellatus, Linn. 



(Fig. 956.) 



(Eng. Bot. t. 651. Flowering Hush.) 



A perennial, with a thick, creeping 

 rootstock, and long, erect, sedge-like 

 triangular radical leaves, broad and 

 sheathing at the base. Flower-stem 

 leafless, 2 to 4 feet high, thick and rush- 

 like, bearing a large umbel of showy, 

 rose-coloured flowers, with 3 lanceolate, 

 thin bracts at its base. Pedicels 3 to 4 

 inches long, often 20 to 30 in the umbel. 

 Perianth full an inch diameter, of 6 

 ovate, spreading, nearly equal segments. 

 Stamens 9. Carpels 6, erect, tapering 

 into short styles, each with numerous 

 minute seeds. 



In watery ditches, and still waters, 

 over the greater part of Europe and 

 Russian Asia, except the extreme north. 

 Dispersed over central and southern 

 England and Ireland, but believed to 

 be introduced only into northern Eng- 

 land and southern Scotland. Fl. summer. 



II. ARROWHEAD. SAGITTAKIA. 



Aquatic herbs, differing from Alisma in their unisexual flowers, the 

 males with numerous stamens, the females with very numerous small 

 carpels in a dense head. 



