796 



THE ALISMA FAMILY. 



chiefly American, but some of them widely distributed over nearly the 

 whole world. 



Flowers numerous, in a loose panicle. Carpels forming a 



ring round the axis of the flower 1 . Common A. 



Flowers few, in a single umbel. Carpels irregularly arranged 

 in a globular head. 

 Stems erect or creeping. Carpels with 4 or 5 prominent 



ribs 2. Lesser A. 



Stems floating. Carpels with 12 to 15 slender ribs ... 3. Floating A. 



1. Common Alisma. Alisma Plantago, Linn. (Fig. 958.) 

 (Eng. Bot. t. 837. Water Plantain.) 



Rootstock perennial, becoming al- 

 most bulbous by the thickened sheath- 

 ing bases of the leafstalks. Leaves ra- 

 dical, varying from ovate to narrow- 

 lanceolate. Flower-stem 1 to 3 feet 

 high, with whorled branches, unequal 

 in length, forming a loose, pyramidal 

 panicle. Flowers rather small, of a pale 

 rose-colour, on long whorled pedicels. 

 Fruit of 20 to 30 carpels, arranged in a 

 single ring round a broad, fiat, central 

 axis. 



In watery ditches, ponds, and edges 

 of streams ; common in Europe and cen- 

 tral and Russian Asia, and North Ame- 

 rica, extending to the Arctic regions, 

 and reappearing in Australia. Abun- 

 dant in Britain, excepting the north of 

 Fig. 958. Scotland. Fl. all summer. 



2. Lesser Alisma. Alisma ranunculoides, Linn. (Fig. 959.) 



(Eng. Bot. t. 326.) 



The leaves and peduncles form annual tufts, but will occasionally 

 emit runners for a succeding year. Leaves narrow-lanceolate, or some- 

 times reduced to a linear leafstalk. Flower-stems, in the ordinary 

 state, simple, with a single terminal umbel, or rarely a second whorl 

 below it. Flowers larger than in the common A., sometimes near an 

 inch diameter. Carpels irregularly arranged in a globular head in the 

 centre of the flower. 



