38 Rhodora [February 



branch may occasionally be found. The variability of the species is 

 best expressed by the leaves, the bracts and the periantlis. The un- 

 derleaves and bracteoles are rather more constant but still vary to a 

 considerable extent. 



On youn^ and slender branches tlie leaves are distant and deeply 

 bifid, with sharp lobes and a sharp sinus, the outline varying from 

 rectangular to ovate, elliptical, or obovat(>. On more robust axes the 

 leaves are usually broader and more or less imbricated, while the a])ical 

 sinus tends to become more and more shallow, varying from acute to 

 lunulate; on many leaves there is no sinus whatever and the apex is 

 truncate. Witii these variations in the situis the lobes show corre- 

 sponding differences, tending to become blunter and blunter, and in a 

 leaf without a sinus the lobes are represented by tiie obtuse or rounded 

 upper angles of the leaf. Althougli the variation follows no definite 

 order, there is a tendency for the truncate leaves to a])])ear in the ujjper 

 part of a fruiting stem. According to Ilowe^ the leaf-cells vary from 

 24 /( to 48 /( in diameter; their walls are thin, but their trigones, al- 

 though small, are usually distinct. Sometimes, however, the cells 

 are thin-walled throughout. The margins of the leaves are connnonly 

 entire but sometinu^s show minute crenulations tine to projecting cells. 



'I'he perigonial bracts, each with a single antheridium, are nearly 

 always in from three to five jjairs just below the two i)erichaetial bracts. 

 Occasionally one of the latter also bears an antheridium. The ex- 

 treme variability exhibited by the perichaetial bracts can be clearly 

 brought by quoting ])ublished descriptions. According to Nees von 

 Escnbeck- they are larger than the stem-leaves, almost erect in the 

 U)wer part but squarrose above, subrectangular in outline and truncate- 

 trilobed at the a])ex, the inni'r of the two being often more deeplv in- 

 ci.sed and toothed than the other. Iliibener'' says that the bracts are 

 denticulate on the margin and two- or three-dentate at the apex, which 

 is squarrose or even refle.xcd. I.impricht^ describes them as being 

 long-rectangular in outline and shortly three to five lobed at the squar- 

 ro.se apex. Warnstorf^ agrees pretty closely with Limj)richt and de- 

 scribes the apex as being truncate and bluntlv two or more lobed. 



' Mem. Torrey Club 7: 116. 1899. 

 "NatiirKescliichte (ler eiirop. Lebeim. 2: 345. 1836. 

 ^ Hep. Germ. 148. 1834. 



^Cohii, lvryj)t .-Flora voii Schlesien 1: 304. 1876. 

 "Kryptogamenfl. der Mark Brandenburg 1: 247. 1902. 



