408 WATER-PARSNEP. 



the water, and seldom reaches a foot in length. The leaves are 

 alternate, pinnate, composed of three or four pair of pinnae and 

 a terminal one, which are ovate, or elliptical, acute, sessile, 

 nearly equally serrated ; those of the radical leaves have some- 

 times a lobe at the base on the upper margin. The flowers 

 are disposed in umbels, which are sessile or nearly so, and op- 

 posite the leaves, composed of six to nine general and partial 

 radii ; the involucre of one deciduous leaf or wanting, the invo- 

 lucel of five to seven ovate-lanceolate reflexed leaves. The 

 calyx is small and indistinct, five-toothed. The five petals are 

 white, ovate, entire, slightly incurved at the apex, and somewhat 

 radiant. The five filaments are slender, spreading, rather 

 longer than the corolla, and tipped with roundish anthers. The 

 germen is small, inferior, supporting two short reflexed styles, 

 terminated by obtuse stigmas. The fruit is ovate-turbinate, 

 slightly compressed laterally. (See Gen. Char.) Plate 47, 

 fig. 2, (a) entire flower, magnified; (b) fruit, natural size; (c) 

 the same magnified. 



This plant is common by the sides of rivulets, lakes and 

 ditches, flowering in July and August. 



The generic name originates in the Greek aiov, which is either 

 a radical word, or as Theis supposes, derived from the Celtic 

 siw, signifying water. The species before us is called provin- 

 cially Water- Skirret. 



The three principal indigenous species of Sium, are the pro- 

 cumbent, (S. nodiflorum,) the broad-leaved, (S. latifolium,) and 

 the narrow-leaved, (S. angustifolium). The Broad-leaved 

 Water-Parsnep, (S. latifolium,) is a strong erect plant, four 

 or five feet high, the leaves pinnated, with oblong-lanceo- 

 late equally serrated leaflets, of which the submersed ones are 

 often much cleft and jagged ; the umbels terminal, and the 

 involucre of several leaves. The Narrow-leaved Water-Pars- 

 nep, (S. angustifolium,) is distinguished by its erect stem from 

 two to three feet in height, pinnate leaves with unequally 

 lobed and serrated leaflets, pedunculate umbels opposite the 

 leaflets, and involucre of several, usually pinnatifid leaves. 

 These, with the species above delineated, (S. nodiflorum,) 

 particularly the latter in its early stages of growth, have 

 been mistaken, by the inexperienced, for Water-Cress ; which 

 is very distinct in the undulated and slightly angular, not 

 aerrated outline of its leaflets, and in the petioles or leaf-stalks 



