132 ENGLISH BOTANY. 



seen OE. fluviatilis growing in still water, and (E. Phcllandrium 

 growing in running water, it would be premature to decide w^liether 

 they be not (in spite of the great difference in habit) merely states 

 of one species. See some remarks on the mode of growth of (E. fluvi- 

 atilis, by Mr. G. E. Varenne in Phytologist, 1852, p. 673. 



Miver IVater-Dropwort. 



GENUS XVIIL—M T H U S A. lAnn. 



Calyx-limb obsolete. Petals obovate, notched, with an inflexcd 

 lobe from the notch. Cremocarp ovate-globose, not compressed ; 

 columella free, bipartite ; mericarps with 5 elevated keeled ridges, 

 the lateral ones a little broader and marginal ; interstices each with 

 a single vitta. Involucre none ; involucel dimidiate. 



An annual or biennial herb, with leaves resembling parsley, but 

 readily distinguishable by its white radiant flowers and umbellules 

 with an involucel of a few long pendulous leaves, all on their outer 

 sides ; and by the short cremocarp with a circular cross-section. 



The origin of the name of this genus of plants is the Greek word ai9w (aitho), I 

 burn ; an acrid taste, in allusion to the qualities of the species. 



SPECIES I.— ^THUSA CYNAPIUM. Linn. 



Plate DC. 



Reich. Ic. Fl. Germ, et Helv. Vol. XXI. Tab. 1901. 

 Billot, Fl. Gall, et Germ. Exsicc. No. 1883. 



Leaves sub-ternately hi- or tri-pinnate ; the leaflets rhomboidal, 

 narrowed towards the base and apex. Involucels dimidiate, of 

 about 3 linear-setaceous pendent leaves, longer than the pedicels. 

 Cremocarp ovate-globular, with thick bluntly-keeled ridges. 



A weed in cultivated ground. Common, and generally distri- 

 buted. Rare in the North of Scotland, though extending to Orkney. 



England, Scotland, Ireland. Annual. Summer 

 and Autumn. 



Poot a slender tapering taproot, whitish. Stem corymbosely 

 branched, 3 inches to 2 feet high. Leaves with short sheathing 

 petioles, all bipinnate, with the leaflets pinnatifid in the lower 

 leaves, so much so that they frequently become tripinnate ; 

 leaflets of the upper leaves acuminate. Umbels small, rather 

 irregular, with 5 to 1,2 widely spreading rays, i to f inch long ; 

 umbellules compact. Involucre none, or rarely of a single leaf ; 

 involucels of about 3 very narrow leaves, i to ^ inch long, hanging 



