169 



#ngi;nal §.rtitlcs. 



ON THE DUMETORUM GROUP OF RUBI IN BRITAIN. 

 By the Hon. J. L. Warren, M.A., F.L.S. 



(Plates CVI., CVII.) 



{Concluded from page 154.) 



Detailed descrvptlons of the Varieties. 



R. dumetorum, a. concinnus, Baker. — Stem arcuate-prostrate, nearly 

 round, rather glaucous and faintly pilose, with fairly strong but rather 

 narrow, long, subpatent not numerous, and rather distant equal prickles 

 with compressed bases and a few setae and aciculi. Stem might pass for 

 corylifolius at first glance, the height of the prickles usually exceeding 

 the breadth of their bases ; prickles themselves longer than those of 

 diversifolius in proportion to the stem breadth ; stem, as compared 

 with diversifolius, singularly free from aciculi and setae. Leaves ter- 

 nate, or a few quinate. Petiole with only 2 to 6 falcate prickles. Sti- 

 pules narrowly lanceolate ; terminal leaflet broadly obovate or almost 

 rhoraboidal, cuspidate, or acuminate, subcordate, often rather narrowed 

 to its base ; intermediate leaflets obovate-acuminate, narrowed to tlieir 

 bases, shortly stalked, scarcely overlapping the terminal leaflet owing 

 to its often elongated petiolule; basal leaflets sessile, obovate-oblong, 

 imbricate. All leaflets thick, coriaceous, green or grey-felted beneath, 

 finely and almost simply deltoid-serrate-deutate, of a dark heavy green 

 above, much lighter coloured beneath. Leaflets generally smaller and 

 neater than in diversifolius, and quite corylifolian in character. The 

 petiolule of the terminal leaflet generally longer in proportion to its 

 leaflet than in diversifolius, and at times about half its length. Flower- 

 ing-shoot nearly round at its base, faintly angular towards its apex, not 

 quite so setose or aciculate as tuberculatus or nearly so setose as diver- 

 sifolius, clothed with faint, close pubescence, and rather slender, few, 

 long, equal, subpatent prickles, not declining as in diversifolius, much 

 fewer and more remote, but nearly of one size and with less elongated 

 tubercular bases ; setae and aciculi very sparse and inconspicuous. 

 Whole flowering-shoot, both in armature, leaf-character, and inflo- 



VOL. VIII. [jUNE 1, 1870.] N 



