﻿MR. JOHN SCOTT ON THE TREE FERNS OF BRITISH SIKKIM. 43 



dex, as shoAviner best the frond-scars 



completely hid in the lower parts with the adventitious roots. At the lower left-hand corner 



ffure 



in yarions stages of development are shown. Nat. size. 



Fig. 2. An aborted shoot of a normal bifurcation of the main axis^ which is now with difficulty dis- 



tinguishable in structure from an adventitious bud from the base of the stipe : a, epidermal 

 layers ; b and 5'^ the inner and outer strata of the woody laminae ; c, vascular bundles of the 

 shoot ; dy a loculus of the stipe ; e^ e, part of a progeny of buds which surrounded the whole 

 surface of the shoot ; /^ the partially decayed apex. 



Fig* 3. Base of stipe^ showing loculi and adventitious buds. 



Fig. 4. Section of base of stipCj showing diaphragm. 



Plate XI. 



Fig. 1. Portion of a young caudex of AlsopMla Andersonii^ with the stout persistent bases of the fronds all 



densely covered with scales. 



Fig. 2 is the base of a stipe denuded of scales, to exhibit the disposition and form of the loculi, which 



are in both respects very irregular. Nat. size. 



Fig. 3. Portion of the caudex oi A. glabra, which, unlike most of the other species, has the long pci- 



sistent bases of the stipes overlapping each other in linear lines, giving it an appearance alto- 

 gether unlike any other tree fern with which I am acquainted. It is singularly proliferous, 

 giving off buds somewhat indifferently from stipes and caudex. The lineal superposition of the 

 fronds is the cause of another peculiarity, in the adventitious roots having first an upward 

 ascent until they reach the broken extremity of the frond below ; thence they pass downwards 

 in a curving radial manner, as shown in the figure. Nat. size. 



J I' 



Fig. 4. Base of stipe of A. glabra^ showing loculi and adventitious rootlets. 



Plate XII. 



Fig. 1. Longitudinal section of half the apical portion of the 'caudex oi Euterpe oleracea, exhibiting the 



arrangement of the vascular system: a, the central parenchymatous mass sparingly interspersed 

 with woody bundles ; ^, a dense zone of the latter, curving round below the flattened apex to the 

 developing bud j c, the looser-structured external zone, with the bundles partly arranged parallel 

 to the axis, and partly in an irregular curving manner ; d, the latter bundles, which have their 

 origin at a later period than the former, and are, moreover, characterized by growth at both 

 extremities, the upper growing up into the frond, the lower downward in the caudex ; e, bases 

 of the fronds, with the nascent inflorescences, /, in their axils ; each frond, it will be observed, 

 originates in the sheathing base of its predecessor. Nat. size. 



Fig. 2. Apical section of the stem of Cycas revoluta, Thunb., exhibiting the straight involute venuition, 



and differing from palms in the free origin of each frond on the apex, as is the case with tree 

 ferns : a, central parenchyma ; b, woody layers ; c, the external layers of parenchyma, inter- 

 spersed with fibro-vascular bundles. 



Fig. 3. Seedling plant of Cycas Rumjjhii, Miq. (C. circinalis, Roxb.), four months old, in longitudinal 



section : d, the central vascular bundle of the main root ; e, adventitious roots ; /, the hardened 



J- 



spermoderm ; g, the perisperm ; the other references as in the previous figure. Nat. size. 



The venation in this species also is straight aiid involute; and the young frond at the stage 

 represented in the figure is not unlike the fertile branch of the Ophioglossums. 



-r 



Fig. 4. An unfolding frond of Cycas sphcErica^ Eoxb., showing the involute character of the vernation. 



Nat. size. 



g2 



