CL. XXII.] DKECIA ENNEANDRIA. 381 



toothed; hoary beneath ; fertile catkins cylindrical ; stigmas eight. 



A tall tree, with silvery smooth bark and ascending branches : 



flowers in March : grows near rivers and on dry heaths, in Nor- 

 folk. Eng. Bot. vol. xxiii. pi. 1619. Eng. Fl. vol. iv. p. 243. 1446. 



3. P. tre'mula. Trembling Poplar. Aspen. Leaves nearly orbi- 

 cular, toothed, smooth on both sides; leaf-stalks compressed; 



stigmas four. A rather tall tree, with smooth bark, remarkable 



for the fluttering motion of its leaves in the wind, caused by their 

 compressed stalks : flowers in March and April : grows in woods, 

 by the sides of rivers, and in clefts of rock : frequent. Eng. Bot. 

 vol. xxvii. pi. 1909. Eng. Fl. vol. iv. p. 244. 1447. 



4. P. nigra. Black Poplar. Leaves deltoid, acute, serrate, smooth 



on both sides ; catkin all loose and cylindrical ; stigmas four. 



A tall tree, with thick blackish bark, and smooth branches. 

 Flowers in March : grows about the banks of rivers : frequent. 

 Eng. Bot. vol. xxvii. pi. 1910. Eng. Fl. vol. iv. p. 245. 1448. 



10. RHODI'OLA. ROSE-ROOT. 



Barren Flowers. Calyx concave, deeply divided into four 

 equal, obtuse, spreading segments. Petals four, lance-shaped, 

 much longer than the calyx. Nectaries four, glandular, notched, 

 opposite to the petals, shorter than the calyx. Filaments eight, 

 awl-shaped, as long as the petals ; anthers roundish. Rudi- 

 ment of four germens with abortive styles and stigmas. 



Fertile Flowers. Calyx as above. Petals smaller. Nectaries 

 as above. Stamens none. Germens four, superior, oblong, 

 three-cornered. Styles short; stigma obtuse. Capsules four, 

 pointed, one-celled. Seeds numerous, roundish. Name from 

 rhodon, a rose, on account of the scent of the root. 454. 



1. B. rosea. Rose-root. Root thick and fleshy, smelling like 

 roses : stems herbaceous, simple, from five inches to a foot high : 

 leaves numerous, scattered, inversely egg-shaped, pointed, serrate 

 at the end, fleshy, glaucous : cyme many-flowered, yellow. Pe- 

 rennial : flowers in May and June : grows on cliffs along the sea, 

 and on high mountains : very common in the northern parts of 

 Scotland and the Hebrides. Eng. Bot. vol. viii. pi. 508. Eng. Fl. 

 vol. iv. p. 246. 1449. 



ENNEANDRIA. 



11. MERCURIA'LIS. MERCURY. 



Barren Flowers. Calyx deeply divided into three egg-shaped 

 spreading segments. Corolla none. Filaments from nine to 

 twelve, hair-like, erect, nearly as long as the calyx ; anthers 

 with globular lobes. 



Fertile Flowers. Calyx and corolla as above. Germen su- 

 perior, roundish, compressed, with a furrow on each side, bristly. 

 Styles two, tapering, rough, spreading ; stigmas acute. Cap- 



