362 SISON. [CLASS V. ORDER II. 



Habitat.-^Pooh, lakes, and inumlated places lliat are dried up in 

 the Summer ; not unfrequent. 



Perennial ; flowering from May to July. 



This plant is readily known from all oilier of our umbellate plants 

 by its slender creeping stems, its variable leaves, and small umbels of 

 few flowers. 



GENUS LTV. SrSON.— Linn. Bastard Stone Parsley. 



Gen. Char. Calyx margin obsolete. Petals roundish, deeply 

 notched and curved with an inflexed point. Fruit ovate, laterally 

 compressed. Carpels with five filiform equal r'uhjes, the lateral 

 ones forming the margins. Channels with short single club- 

 shaped ritta. Albumen convex at the back, plain in front. 

 General and partial involucre of few segments. — Name, according 

 to Theis, originating in the Celtic sizun, a runnin(j brook; some 

 of the plants formerly placed in this genus delighting in such 

 situations. 

 1. .S. Amo'mum, Linn. (Fig. 426.) Hedge Bastard Stone Parsley. 

 English Botany, t. 954. — English Flora, vol. ii. p. 60. — Hooker, 

 British Flora, vol. i. p. T29. — Lindley, Synopsis, p. 122. 



Root tapering, fleshy. Stem erect, from three to four feet high, with 

 numerous alternate slender wiry branches, smooth, striated. Leaves 

 pinnate, of a dark green, smooth, leaflets ovate, deeply cut and serrated, 

 the terminal one mostly three lobed, the upper leaves cut into narrow 

 unequally serrated segments, footstalks with a dilated membranous 

 edge, the base half embracing the stem. Umbels mostly numerous ; 

 general of about four unequal rays ; partial of numerous short un- 

 equal ones. Jyivolucre irregular; general of about four lanceolate 

 segments ; partial of about four smaller ones. Flou-ers white, or straw 

 colour. Calyx an obtuse margin. Petals roundish, or inversely 

 heart-shaped, from being deeply notched at the cxtremiiy by the in- 

 flexion of the small point. Stamens alternating with the petals. 

 Filaments slender. Anthers yellow, small, roundish. Styles very 

 short. Stigma obtuse, small. Disk large, swollen fleshy. Fruit 

 small, ovate. Carpel sides somewhat compressed, with obtuse ridges, 

 three at the back, the two lateral ones forming the margin. Vittte 

 small, club-shaped. Albumen on a transverse section, very convex at 

 the back, corapres.sed, or slightly plain in front. 



Habitat. — Chalky and limestone districts, in a moist soil in shady 

 situations; not very frequent in England. Near Coldstream, Scot- 

 land.- Miss E. Bell. 



Biennial ; flowering in August. 



