114 ON THE SPECIFIC RANK OF POTAMOOETON ZIZXL 



most generally distributed heathland plants in S. England. B. 



Muenteri Marss. (St. sulcate. L. green on both sides, and rather 

 more coarsely serrate. Inflor. narrow) and R. Maasii Focke (St. 

 quite glabrous, and sep. greener) seem hardly separable from it. 



b. R. pulcherrimus Neum. R. polyanthemus Lindeb. (Jonrn. Bot. 

 1890, pp. 131, 166). — Prickles more numerous, straight or slightly 

 declining, much compressed, rather unequal and scattered; occasionally 

 with some aciculi and stalked glands intermixed. • L. and Its. as in 

 R. ? dnmosus, but sometimes white -felted beneath. Pan. with stalked 

 glands (especially on the bracts), and sometimes a few aciculi, 

 besides the slender declining prickles. Pet. small, bright pink, 

 broadly elliptic or roundish, with very short claw. Generally dis- 

 tributed, and by no means confined to open places. A bramble 

 not easy to place ; often (when not in flower) distinguished with 

 difficulty from dumosns, at other times almost as strongly armed as 

 some of the Radula. 



e. R. Lindebergii P. J. Muell — St. tall, arcuate-prostrate, acute- 

 angled, pale. Prickles much as in dumosns. L. all 5-nate. Lts. 

 rather small, distant, uniform, acuminate and narrowing a good deal, 

 though very gradually, from above the middle to the rounded or slightly 

 emarginate base, with formal simply- serrate outline ; grey-green above, 

 grey-felted beneath. Pan. long, narrow, eglandular, with many strong 

 falcate yellow prickles, and, crowded short few -flowered branches. Fl. 

 'large and showy. Pet. always white, obovate, tapering gradually 

 into long claw. Fil. white, far exceeding greenish styles. A constant 

 and strongly marked form ; in the North (in hilly limestone dis- 

 tricts, at all events) appearing (with R. ptilcherrimus) to take the 

 place of both R. rhamnifolms and R. ? dumosus. 



15. E. incurvattjs Bab. — St. arcuate -prostrate, angular and 

 furrowed, dull red, rather hairy. Prickles many, strong, slightly 

 declining from compressed triangular base. L. 5-nate. Lts. lobate- 



dentate, very thick, remarkably concave from the upturned wavy edges, 

 shining and subglabrous above, very softly greenish-ichite-felted 

 beneath; term, broadly ovate (or obovate) acuminate cordate. Pan. 

 long, narrow, u-ith many short corymbose branches, which as a rule are 

 all (except the lowest two or three) remarkably patent. Sep. 

 coloured like the under surface of the 1., with long acuminate points. 

 Pet. (broadly obovate), stam. and styles all pink. A beautiful and 

 well-marked bramble. Hilly slopes, thickets and heaths, especially 



in the west. 



(To be continued.^ 



ON THE SPECIFIC KANK OF POTAMOGETON ZIZII. 



By Alfred Fbyer. 



Botanists who have made a critical study of Potamogeton have 



„_ greatly m 



Zizii bears to the other species of the genus, and have variously 

 assigned it as a subspecies to two such widely different species as 



