ALTSMACE^. 497 



In wet ditches, bogs and marshes, over the greater part of Europe, from 

 Spam to southern Sweden, but rare m the east. In Britain, as widely 

 dispersed as tl\e common A., but not near so frequent. Fl. summer and 

 autumn. Occasionally the flowering-stem bends down, and forms fresh, 

 rooting, and leafy tufts at each whorl of flowers. This state has been 

 described as a species, under the name of the creeping A. {A. repens, Eng. 

 Bot. Suppl. t. 2722). 



3. Floating Alisma. Alisma natans, Linn. 

 (Eng. Bot. t. 775.) 



Very near the creeping varieties of the lesser A. Stems slender, and 

 floating on the surface of the water, producing at every node a tuft of small 

 ovate or oblong, stalked leaves, and 2 or 3 flowers like those of the lesser A., 

 wliilst the radical leaves of the original tuft are all reduced to a linear leaf- 

 stalk, scarcely dilated towards the top. Carpels in a globular head, like 

 those of the lesser A., but much more pointed, and marked with 12 to 15 

 slender longitudinal ribs. 



In ponds and still waters, in western and some parts of central Europe ; 

 not observed in southern Europe, and extending northward only to Den- 

 mark and western Scandinavia. In Britain, scattered over a few localities 

 in western England, and more plentiful in western Ireland. Fl. summer 

 and autumn. 



IV. DAMASONIUIYI. DAMASONIUM. 



Herbs, only differing from Alisma in the carpels, which are few, larger, 

 usually 2-seeded, and cohere by the base to the central axis of the flower. 



Besides the European species, the genus comprises two others from 

 Australia and California. 



1. Star Damasonium. Damasonium stellatum, Pers. 

 {Alisma Damasonitim, Eng. Bot. t. 1615. Actinocarpus, Brit. Fl.) 



A tufted, glabrous annual. Leaves all radical, on long stalks, ovate or 

 oblong, often cordate at the base. Flower-stems erect, from 3 or 4, to 8 or 

 9 inches high, usually bearing 1 terminal umbel, and 1, 2, or 3 whorls of 

 rather small flowers lower down. Inner segments of the perianth or petals 

 very dehcate, white, with a yellow spot at the base. Carpels 6, tapering 

 into a long point, and radiating horizontally, like a star. 



In watery ditches, and pools, in western and southern Europe, and west • 

 central Asia, but not extending into Grermany or Scandinavia. In Britain, 

 only in some of the southern and eastern counties of England. Fl. summer. 



V. SCKEUCHZERIA. SCHEUCHZERIA. 



A single species, distinguished from the preceding genera as well by 

 its habit and inflorescence, as by the smaller, more herbaceous perianth, on 

 wliich account this and the following genus are often separated as a family, 

 under the name of Juncaginem. 



1. Marsh Scheuchzeria. Scheuchzeria palustris, Linn. 

 (Eng. Bot. t. 1801.) 

 A rush-like perennial, with a creeping rootstock, and an erect stem about 



2 u a 



