﻿28 MR. JOHN SCOTT ON THE TREE FERNS OF BRITISH STKKIM. 



I 



in those buds which, originating on the base of the stipes, have a direct connexion with 

 the interior parts of the stem by the meshes of the fronds, as compared with the fre- 

 quently occurring early arrested ramification of the stem. The buds of tree ferns arc all 

 truly adventitious, and distinct from the axillary buds of pheenogams ; and in no case 

 have I observed them on the surface of the frond, as in many of the dwarf herbaceous 

 species. Eamifications of the main axis are produced either by suppression of the 

 growing point and the development of lateral shoots, or by simple or more or less com- 

 pound bifurcations. Illustrations of these have been given. The prolificness and axial 

 •amifications of the dwarfer species of ferns are in no respect different from those of the 

 arborescent species. 



18. Concluding remarks on the anatomical relations of the Caudex.—ThOi arborescent 

 ferns present somewhat complicated affinities, and, it must be admitted, no very close 

 relations beyond their own alliance, which may be largely due to their ancient origin. 

 So far as known, they appeared first in the Devonian period, were largely represented, 

 and apparently formed one of the most striking features of the succeeding Carboniferous 

 flora, whence they have persisted, without any marked change, to diversify and enrich 

 all subsequent floras. The tree ferns at the present day, as in their most ancient repre- 

 sentatives, are characterized by a soft cellular central part, surrounded by a woody 

 cylinder, which is again enveloped in a hardened cortex, exteriorly marked by lar-e 

 elliptical or rhomboidal scars, left by the fall of the fronds, and also (as in the Psaronites 

 of the Permian period) by a dense mass of adventitious roots much exceeding in thickness 

 the caudex. The frond-arrangement also, as indicated by the scars, is similar in ancient 

 and modern species. Thus in the majority of the latter the arrangement is quincuncial, 

 as was the case m Caulopterls prlmceva and others of the Carboniferous epoch • or a-ain 

 as m Alsophila glabra, the scars are in continuous Knes parallel to the longitudinaraxis 

 of the caudex, as was likewise the arrangement in the ancient Ft^choj^teris macrodis- 

 2 In those epochs there was no lack of related forms, as the gigantic Lepidoden^ 



cTads r;r ". T ""' '' "'"^ *^^ '""'''^ ^^^^^^*^ *^^- --y closely with 



Lw find tl! r\^"' '"' ''^ '^"^ P"^^'^ '' ^™^^^ ^-^ -^-' tion; L u 



;;:; a^^^^^^^^^^^^^ '-- ^' ^- ^^^-^-^ --^ i^ -uld and structure 



The relations, as founded on the structure of the stem, when we pass bevond their 

 own aUiances are perhaps, upon the whole, closest with Palms, thourrthey also eem 



and 



to have much 



cnai-actenstics. In both diampfiW^on j i -. ., — ^"^^^ ^^^J sm 



both the stems are 2eJ ^ Sh J '"T '^''^' S-^^h is strictly apical 



