Alisnia.] ALisMACEiE. 531 



Order LXXIX. ALISMACE^, R. Br. 



" Perianth of 6 pieces ; 3 outer sepals herbaceous, 3 inner peta- 

 loid. Stamens hypogynpus. Ovaries several, superior, distinct 

 or slightly united at the base, each 1-celled. Ovules solitary, or 

 2 superposed, attached to the inner angle of the carpel. Peri- 

 carps indehiscent. Seeds solitary, or 2 attached to the suture at 

 a distance from each other, erect or ascending. Albumen 0. 

 Embryo undivided, curved like a horse-shoe, with the same direc- 

 tion as the seed. — Aquatics. Leaves radical, on long stalks." — 

 Br. Fl. 



I. Alisma, Linn. Water Plantain. 



"Flowers perfect. Stamens 6. Styles numerous. Achenes 

 many in a head, distinct, 1-seeded." — Br. Fl. 



1. A. Plantago, L. Common or Great Water Plantain. 

 " Leaves aU radical cordato-ovate or lanceolate, scape panicled 

 with whorled compound branches, fruit depressed, achenes obtuse 

 with a small rib on the back."— ^r. Fl. p. 457. E. B. t. 837. 



Tn ponds, ditches and slow streams ; very common. FLSune — August. 1(. 



2. A. ranunculoides, L. Lesser Water Plantain. " Leaves all 

 radical linear-lanceolate, scape with simple branches in one or 

 two whorls, fruit globose squarrose, achenes obliquely ovate acute 

 5 -angled."— Br. Fl. p. 457. E. B. t. 326. 



Ditches and shallow pools ; not common. Fl. May — September. O- 



E. Med. — In one or two of the marsh-ditches on Sandown level, towards Alver- 

 stone, in tolerable plenty, with Polygonum minus, 1849. In Dashmere pool, at 

 the foot of Bleak down, by the junction of the roads to Chale, Chillerton and 

 Godshill. 



W. Med. — Abundant in marsh-ditches at Freshwater gate, and occasionally in 

 other parts of that parish, also near Yarmouth, but much more sparingly. In a 

 pool on a large furzy common called Goldens, Freshwater. Old clay-pit in 

 Hampstead brick-field. In a pool between Yarmouth and Ningwood common, in 

 a field between the road and Leigh wood, 1843. 



Whole plant perfectly smooth and glabrous. Root a dense tuft of long, white, 

 simple fibres, slightly creeping or at least emitting short lateral shoots, producing 

 other plants contiguous to one another or in clumps. Leaves numerous, entirely 

 radical, erect, pale green, very narrowly lanceolate or linear-lanceolate, acute and 

 entire, firm, obscurely 3-ribbed, the middle rib forming a rather prominent keel 

 beneath into their often span-long semiterete petioles, which are very vascular and 

 spongy, mostly purplish, finely striated and reticulated with transverse septae, 

 tapering gradually from their whitish, imbricating, scariosely edged bases: the 

 earlier leaves are, as Bertoloni remarks, quite linear and evanescent. Scape 1 or 

 more (seldom above 2 or 3), erect or decumbent, as tall as or taller than the leaves, 

 terete, simple, usually about a span and seldom exceeding a foot in height, termi- 

 nated by an umbellate whorl of several unequal simple flower-stalks, from the 

 centre of which are often produced one or two similar whorls, distant from the 

 first or lowermost from being elevated on a prolongation of the scape or common 



3x 



