132 EXGLISU BOTANY. 



seen CE. fluviatilis growing in still water, and CE. Phellandrium 

 growing in running water, it would be premature to decide whether 

 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 CE. fluvi- 

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



River Water-Dropwoft. 



GENVS XVIII— M THUSA. Linn. 



Calyx-limb obsolete. Petals obovatc, notched, with an inflcxed 

 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 m6u> (aitho), I 

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



SPECIES L-iETHUS A CYNAPIUM. Linn. 



Plate DC. 



Reich Ic. Fl. Germ, et Helv. Vol. XXI. Tab. 1001. 

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



Leaves sub-ternately bi- 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. 



Root a slender tapering taproot, whitish. Stem corymbosely 

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

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

 haves, so much so that they frequently become tnpmnate ; 

 leaflets of the upper leaves acuminate. Umbels small, -rather 

 irregular, with 5 to 12 widely spreading rays, \ to finch Ion--; 

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

 iuvoluccls of about 3 very narrow leaves, '. to h inch long, hanging 



