Dicecia . 
161 
Pop, Nigra , Black Poplar ; with rhomboidal, point- 
ed, serrated leaves, smooth on both sides ; a lofty tree, 
which grows on banks of rivers, and in watery places. 
Rhodiola. Gen. char.-—{ 1 ) Cal. four-parted ; pe- 
tals four ; nectaries four, notched. (2) Cal. four-part- 
ed ; petals four ; nectaries four, notched ; pistils four ; 
caps, four ; many-seeded. 
Rhod. Rosea, Rose-root. On the mountains of 
Wales and Yorkshire, and frequent on the rocky shores 
of the Western Islands of Scotland : it is easily recog- 
nised by its succulent, smooth, azure, imbricated leaves, 
and yellowish flowers. 
Enneandria. ■ 
Mercurialis. Gen. char.~—{\) Cal. three-part- 
ed ; cor. none ; stamens from nine to twelve. (2) Cal. 
three-parted ; cor. none ; styles two ; caps, two-celled; 
seeds single. 
Merc. Perennis , Perennial Dog’s Mercury ; with 
very simple stem, rough leaves, and creeping root. 
Perennial ; flowers in April and May, and is common 
among brushwood. 
To an inexperienced eye this plant has something of 
the appearance of spearmint, and has been used by 
mistake in the form of infusion, with fatal effects to 
those who swallowed it. It is said also to be equally 
deleterious to other animals, sheep, for example, as to 
man. 
