VILLICAULES. 97 



Group III. Villicaules. 



Caules plus minusve arcuati, radicantes, pilosi vel 

 calvati, saepe tomentosi, glandulis subsessilibus ; vel 

 raro setosi aciculatique. Aculei in caulis angulis con- 

 gesti, subiBquales; vel etiam paucis minoribiis sparcis. 

 Foliola infima petiolata intermediis dissita (R. Gra- 

 howskio excepto). 



There are two ways iu which the Ruhi Villicaules may 

 be divided into minor groups. If the direction of the stem 

 is alone considered we have (1) those plants in which it is 

 erect-arcuate, often never reaching the ground so as to root 

 at the end, or only doing so by means of a slender nearly 

 leafless autumnal shoot. These stems are usually very erect 

 and strong enough to support themselves in an upright 

 position. Such plants are R. carpinifolius and it. thyrsoi- 

 deus. — (2) The stems are truly arcuate and nearly always 

 reach the ground and root (not requiring a special autumnal 

 shoot to do so), but rarely have much if any prostrate portion 

 at the end. The arch is lofty and self-supporting. Here 

 we may place R. Grahowskii, R. villicaulis and R. mucronu- 

 latus. — (3) The other plants included in the group have 

 arcuate-prostrate stems when left without any foreign sup- 

 port, and the prostrate part is usually very long relatively 

 to the low arch formed near the base of the stem. But this 

 mode of subdivision is far from being satisfactory. It 

 separates to a long distance from each other some very 

 closely allied plants and places together others which have 

 not much in common. 



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