50 KNr.LTsn r.OTANT. 



Leaves all similar, sessile and semiamplcxicaul, narrowly linear, .veiy 

 sliffhtly narrowed towards the base, subacute or subobtuse, with 3 

 (rarely only 1) lonsjitudinal ribs without fainter ones between them, 

 mostly without axillary fascicles of leaves. Stij)ules small, subacute, 

 subscarious, with numerous slender longitudinal fibres. Peduncles 

 terminal between the forks of the stem, longer than the stem (usually 

 twice as long, or even more), filiform, not thickened upwards. Sepals 

 with their lamina suborbicular. Pistils 4. Fruiting-spike oblong- 

 ovoid, not interrupted, few-flowered. Fruit small, greenish-olive, 

 scarcely compressed, acuminated, convex on the upper margin, on 

 which there is no tooth, half oval-obovate and very bluntly 3-keelcd 

 on the back, terminated by a rather short, central, slightly recurved 

 beak. Plant rather dull deep green, becoming darker when dried. 



Var. a, vulgaris. 



Plate MCCCCXIX. 



BeicTi. Ic. n. Germ, et Helv. Vol. VII. Tab. XXH. Pig. 38. 



Leaves 3-nerved, subacute. 



4 



Var. /3, tenuissinms. Fries. 



Plate MCCCCXX. 

 BekTi. Ic. Fl. Germ, et Helv. Vol. VII. Tab. XXII. Fig. 39. 



Leaves very narrow, cuspidate, 3-nerved or 1-nerved, whole plant 

 smaller than var. a, and with the leaves more divaricate. 



In ponds and ditches. Eather common, and generally distributed, 

 ranging from Cornwall, Dorset, Kent, and Sussex, northward to 

 Orkney. Frequent throughout Ireland. 



England, Scotland, Ireland. Perennial. Summer 



Stems very slender, usually branched. Leaves f to 2 inches long, 

 rarely above j'^ inch broad, and in var. scarcely above y'^.- inch. 

 Peduncles (exclusive of the spike) i to 1 inch long, much more slender 

 than in any of the preceding species. Fruiting-spike \ to }^ inch long. 

 Nuts j'2 inch long. 



From P. mucronatus this differs in its more slender and uncom- 

 pressed stem, its narrower leaves, witli not more than three veins, and 

 with their base much less narrowed, their apex less acuminate, their 

 much more slender peduncles, and tlic smaller, less compressed fruit, 

 n)ore convex on the lower side, and with the beak rather longer m pro- 

 jjortion. Besides these characteristics, the mode of growth is different, 

 tlie leaves are not so far apart, and have not fascicles of leaves or very 

 short branches in their axils, which is almost always the case in P. 



