PAPILIONACE^. 



233 



9. Tuberous Pea. Lathyrus maerorrhizus, Wimm. (Fig. 291.) 

 {Orobus tuberosus, Eng. Bot. t. 1153.) 



Root-stock perennial, forminf small 

 tubers ; the annual stems glabrous, 

 nearly erect, simple or nearly so, 6 inches 

 to a foot high. Leaves without tendrils ; 

 the leafstalk ending in a fine point, or 

 sometimes in a narrow leaflet ; the leaf- 

 lets usually 2 pairs, sometimes 3 or even 

 4 pairs, oblong-lanceolate or linear. 

 Peduncles slender, bearing a loose ra- 

 ceme of 2 to 4 flowers of a bright reddish- 

 purple. Pod glabrous, about 1J inches 

 long. The whole plant dries black like 

 the following species. 



In thickets and open woods, under 

 hedges, etc., throughout Europe, except 

 the extreme north. Abundant in Bri- 

 tain. Fl. spring and early summer, This and the blade _P. form part 

 of the old genus Orobus, still kept up by many botanists, but only 

 differing from Pea by the want of tendrils to the leaves. 



Fig. 291. 



10. Black Pea. Lathyrus niger, Wimm. (Fig. 292.) 

 {Orobus, Eng. Bot. Suppl. t. 2788.) 



A glabrous perennial, always turning 

 black in drying ; the rootstock short 

 and not tuberous ; the stems erect or 

 ascending, branched, 1 to 2 feet high or 

 even more. Stipules small and narrow. 

 Leaflets 4 to 6 pairs to each leaf, ovate 

 or elliptical, 6 lines to an inch long, the 

 common stalk ending in a short point. 

 Peduncles longer than the leaves, with a 

 short raceme of 6 to 8 flowers. Pod 

 glabrous, near 2 inches long. 



In mountainous and rocky districts, 

 throughout temperate Europe to the 

 Caucasus, extending far into Scandi- 

 navia. In Britain, only known from two 

 localities, in Perth and Forfar. FL sum- 

 mer. 



Fig. 292. 



TOL. I. 



