—52— 



I find only two pronounced extremes in this reduction from the species. 

 One of these is the variety densuin, with longer leaf points ; the larger forms 

 of this occur all over Europe, and in North America ; the slender forms include 

 Fowler's plant from Scotland, Williams" from the Yukon region, and 

 Ditrichum Macoiniii. The other of them is not so common, but occurs in 

 England, in Northamptonshire, coll. Dixon ("teste Braithw." ), in Canada, 

 Rocky Mts. (D. fle.xicaule brcvifoliiiin^D. e latum Kindb), at.d abundantly 

 in the upper Mississippi valley. It seems to me that Dr. Kindberg's first 

 name Ditrichum fle.xicaule brevifoiiuin, very appropriate for this short- 

 leafed form, should stand. But I hardly think that either D. datum or D. 

 Macounii, will eventually stand as different species. 



CLIMAClUn WEB. & MOHR. ITER SUEC. 96. 1804. 



Large handsome mosses with a tree-like habit of growth from under- 

 ground creeping stems (Fig. 1. a). vSometimes prostrate, or floating in 

 very wet places. Stem and branches-bearing paraphyllia (/. e. branch- 

 ing filaments which are chlorophyll-bearing). The leaves are arranged 

 evenly on all sides of the stems and branches and are all somewhat decur- 

 rent but vary greatly in shape and structure. The leaves figured are from 

 the middle of well developed branches. The leaves of the main upright 

 stems are very large, thin, with little chlorophyll, closely imbricated and 

 clasping. Branch leaves smaller, of a different shape and texture, chloro- 

 phyllose. All our species are dioicous. The seta is long and smooth, 

 twisted to the right when dry. Calyptra split on one side, long, reaching to 

 the base of the capsule. Capsule erect, cylindric; operculum conic-rostate 

 with the beak often oblique; annulus none; peristome double; teeth linear- 

 lanceolate, very long, closely articulate, minutely papillose, without the 

 fine transverse lines on the lower part of the teeth that characterize the 

 Hypnaceae; segments as long as the teeth, keeled, split between the 

 articulations, often split to the apex when old, united at the base into a 

 continuous narrow basal membrane, minutely papillose; spores minutely 

 papillose. 



Mosses of swampy woods and fields ; fruiting with comparative infre- 

 quency. The systematic position of this genus is as yet undetermined. It 

 certainly does not belong in the Isotheciae where it has previously been 

 placed. The lack of transverse lines on the peristome teeth indicates that 

 it is either not closely related to the Hypnaceae or else is a very highly modi- 

 fied member of that family. It has been placed with the Fontinalaceae but 

 there is much to be said against this view. Perhaps a separate subfamily 

 Climaceae of the Hypnaceae will be as satisfactory arrangement as can be 

 made with our present knowledge. There are three species known to North 

 America, one of which, C. dendrotdes, is common in Europe. 



I. Capsules 3 to 4 times as long as broad; median leaf cells 



10 times as long as broad, C dendroides. 



Capsules 5-6: i ; median leaf cells 2-7: i, 2. 



