CL. XXII.] DIGSCIA 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 livers and on dry heaths, in .Norfolk. Eng. Bot. 

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



3. P. tremnla. Trembling Poplar. Aspen. Leaves nearly orbicular, 



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 rocks : 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. RHODl'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. Rudiment 

 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. R.riisea. Rose-root. Root thick and fleshy, smelling like roses: 

 stems herbaceous, simple, from five inches to a foot high : leaves nume- 

 rous, scattered, inversely egg-shaped, pointed, serrate at the end, fleshy, 

 glaucous ; cyme many-flowered, yellow. Perennial : 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. 1 449. 



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. Capsule 

 2 K 



