Fam. 4. POLYTRICHACE^. 



Mosses variable in size and habit ; sometimes short and simple, 

 sometimes very tall, dendroid and branched, with the stem highly 

 developed, having a central woody axis. 



Innovations basal, or in the male plants the axis is continued 

 from the centre of the inflorescence. Leaves firm and rigid, the nerve 

 generally expanded and bearing on the upper surface a variable 

 number of more or less developed vertical lamellae, which vanish 

 toward the sheathing base of the leaf; the margin usually serrate, the 

 cells of the non-lamellose part mnioid. 



Inflorescence almost always dioicous, the male discoid with the 

 bracts often coloured. 



Calyptra cucuUate, naked or spinulose or with a few hairs, or 

 most frequently covered with long villose pendent hairs. Capsule 

 on a long wiry pedicel, terete or angular or rarely depressed, with 

 stomata frequently present in the cuticle. 



Peristome of 32 or 64 erect, solid, linguiform teeth, united at 

 apex to the discoidal dilated extremity of the columella (the epiphragm 

 or tympanum) ; sometimes broken up into a pencil of cilia ; very rarely 

 none. Inhabiting the ground, especially on moorlands, and often 

 occupying extensive tracts. 



This great family of 200 or more species, is a most natural one, 

 approaching the Mniaceas in some points, but yet possessed of characters 

 quite peculiar ; notably the solid tongue-shaped teeth, the membranous 

 dilated discoid top of the columella, the lamelligerous leaves, and the 

 densely pilose calyptra. By the well-developed fibro-vascular cells forming 

 a woody axis to the stem, and the noble tree like habit of some exotic 

 forms, we may perhaps regard them as standing at thfe head of all mosses. 



The structure of the peristomial teeth is well worth a careful examina- 

 tion, as it differs from that of all other mosses. Each tooth consists of 

 several layers of fine threads, held together by cellular material, and we 

 can trace each thread down from the apex of one tooth, through the basal 

 membrane, and up again to the apex of the adjacent tooth, those in the 

 axial line being more condensed. The basal membrane is a continuation 

 of the lining of the capsule (endothecal membrane), and consists of several 

 rows of thick-walled rectangular cells. 



Prof. Schimper divides the Polytrichaceee into three sub-families : 

 I. Polytricheae, comprising nearly all the species. 2. Lyellieae, for the 

 genus Lyellia, containing two East Indian species, remarkable for the 

 absence of peristome, though with a button shaped epiphragm closing the 

 mouth of the capsule. 3. Dawsonieae, including the Australian genus 

 Dawsonia of 4 species, among which stands D. superba, one of the most 



