110 KEY TO BRITISH PJ)Bl» 



b. hemistemon (P. J. Muell.). — Adult 1. hardly plicate, irre- 

 gularly dentate, paler and hairier than in plicatus. Lts. oval, with 

 long acuminate points; bas. shortly petioled. Stipules filiform, 

 ciliate. Stam. variable in length, but usually falling considerably 

 short of the greenish styles. Pet. oval, white. Sep. partly clasping 

 fruit. Heaths and commons. 



(2) Stam. exceeding styles. Bas. Its. already in summer briefly 

 but distinctly petioled. 



5. R. nitidus W. & N. — Prickles nearly straight, much com- 

 pressed, with small bases. Adult 1. plane, irregularly serrate- 

 dentate, bright green and shining above. Lts. narrower than in 

 plicatus; term, oval or elliptic, acute; bas. distinctly stalked. 

 Stipules very narrow. Pet. oval. Cal. sometimes armed. When 

 quite typical (as I have seen it in Surrey and Hants, and from 

 N. Wales), the pan. is rather broad, with many nearly patent 

 branches, crowded uniform strongly hooked prickles, quite green 

 sep. and rather small bright pink pet. (the R. hamuimm Lefr. & 

 Muell. having white ones) ; but this species is quite as variable as 

 plicatus, though usually readily distinguishable from it by the leaf- 

 characters and the long stamens. 



b. ? integribasis (P. J. Muell. ).— Prickles declining or deflexed, 

 from oblong bases. L. opaque above, paler beneath. Lts. acumi- 

 nate or cuspidate-acuminate, often obovate, with shallower teeth, 

 and rather narrow entire or subcordate base. Pan. narrower, and 

 much less strongly armed, with shorter declining or mixed prickles. 

 Pet. pale pink, longer and narrower than in the type. ^ Sep. 

 greyish. Most of our British nitidus comes best under this var., 

 which occasionally recalls some forms of the aggregate, R. nemoralis 

 P. J. Muell. (R. umbrosus Auct. Angl.). In S.W. Surrey its place 

 is taken by what seems an allied but much stronger form with very 

 large fl., which grows abundantly on the same heaths and commons 

 as the typical plant. 



6. R. opacus Focke. — Prickles much compressed, declining, 

 with long slender point. L. large, greyish, and felted beneath 

 when young. Term. It. cordate-ovate, very gradually tapering to a 

 point. Pan. rather narrow, racemose above, with term. fl. nearly 

 sessile, quite unarmed or with a few weak declining prickles. Like 

 R. nitidus in its lonsr stam. and stalked bas. Its., but recalling 



o 



!0 



In Focke's %>/. R. G. it follows plicatus 9 as being perhaps of hybrid 

 origin (" R. ajfinis x plicatit*t ft )* Heatli3 and commons (Derb., 

 and several counties in the South). 



b. Sep. reflexed in fruit. Stam. exceeding styles. 



7. R. ammobius Focke. 



with 



prickles, larger 1. not unfrequently 7-nate, and broader Its. plicate 

 only when young and then usually grey beneath, larger fl., stam. 

 slightly exceeding styles, and sep. reflexed in fruit. Believed to 

 occur in Scotland. I have not seen it. 



* 8. R. sulcatus Vest. — St. sulcate throughout. Prickles few, 

 strong, with large bases. L. all 5-nate. Bas. Its. stalked. Pan. 



