CHAEA CONTRARIA. 39 



between the primary and secondary series is usually well marked, 

 but is occasionally inconsiderable, when it is necessary to examine 

 the stem in transverse section. C. contraria is usually more 

 slender and rigid, and there is a certain neatness in its aspect 

 which to the practised eye serves to distinguished it in the field 

 from the somewhat more loosely-built and rougher C. vulgaris. 

 The stipulodes are less regular than in that species. _ 



An account of the anatomy of C. contraria by Mdlle. Cath*. 

 Sluiter, with numerous illustrations, will be found in ' Bot. Zeit.' 

 LXVIII, p. 125 (1910). 



We have seen no root bulbils in this species. 



The variation, though less extensive, is much on the same lines 

 as with C. vulgaris, an analysis of which will be found under that 

 species. Among the British forms, it may be roughly summarized 

 as follows : — 



The stature ranges from a small tufted form 3-4 inches high, 

 with short internodes, to a much-drawn-out form several feet in 

 length with very long internodes ; the diameter of the stem 

 from c. 400 fj to c. 1100 /n ; the stipulodes from minute and 

 papilliform, to both series well developed cylindrical; the primary 

 cortical-cells from nearly the same size as, to twice the diameter 

 of, the secondary ; the spine-cells from papilhf orm to cylindrical ; 

 the branchlets from short, stout and strongly-incurved to long, 

 slender and flexuous ; the branchlet-segments from almost all 

 corticate and diminishing gradually in length and thickness to 

 having the three or four segments below the apex ecorticate, 

 swollen and elongated ; the anterior bract-cells from shorter 

 than, to 2-3 times the length of, the fruit ; the oospore from 

 broadly-ellipsoid to cylindric-ellipsoid. While the more robust 

 states resemble in facies forms of C. vulgaris, the most slender 

 are almost like the extended form of C. aspera. A much elon- 

 gated sterile form collected by G. E. B.-W. in Wicken Fen 

 resembles C. jubata in having very long internodes, about 4 times 

 the length of the much reduced branchlets. A curious little 

 form, with short very stout and strongly-incurved branchlets, 

 occurs in the central Irish lakes. 



This species was first discriminated and named by Braun, 

 but, as in many other cases, Kiitzing must be cited as the 

 authority, having first published a description of it, though a 

 very inadequate one. 



