LYCOPODJACE^ 



63 



and apiculate, and are penetrated by a single ' vascular ' bundle ; those 



which subtend the sporanges are much smaller, and apparently deeply 



bifid, in consequence of their becoming connate 



at their base in pairs. In Psilotum the leaves 



are reduced to mere scales without any 'vascular' 



bundle. 



The sporanges of the Psilotese differ from 

 those of the Lycopodiese in not being formed in 

 connection with the leaves, and in being pluri- 

 locular. They are collected into spikes which 

 are formed at the growing point of a primary 

 shoot. In Tmesipteris each spike usually consists 

 of two sporanges only, situated in the fork be- 

 tween two connate or one bifid fertile leaf ; they 

 are oblong and bilocular, and dehisce by two 

 vertical slits ; the spores are very minute, oblong, 

 and curved. In Psilotum the sporanges are col- 

 lected into groups of three or four 

 on special shott lateral branches, 

 each in the axil of a rudimentary 

 leaf, and forming a loose spike. 

 They are turbinate in form, and 

 are divided into three compart- 

 ments, less often into two or four ; 

 each locule dehisces by a vertical 

 fissure. The germination of the 

 spores and the oophyte generation 

 are entirely unknown in the order. 



Psilotum consists of two spe- 

 cies, natives of the tropical regions of both hemispheres, having the 

 appearance of small branching nearly leafless shrubs ; Tmesipteris of 

 a single known species, epiphytic on the trunks of tree-ferns, with a 

 pendulous habit, in the Southern Hemisphere. 



Fig. 41. — Tmesipteris tannensis Bernh. A, por-^ 

 tion of branch (natural size); B, sporange 

 and subtending leaves (magnified). 



Literature. 



Spring — Monograph des Lycopodiacees in M^m. Acad 



1849. 

 Cramer — (L. Selago) in Nageli u. Cramer's Pflanzenphys. 

 De Bary — (Germination) Naturf. Gesell. Freiburg, 1858. 

 Mettenius— (Phylloglossum) Bot. Zeit., 1867, p. 97. 

 Payer— Botanique Cryptogamique, 1868. 

 Juranyi— (Psilotum) Bot. Zeit., 1871, p. 177. 

 Hegelmaier— Bot. Zeit., 1872, pp. ^<)% et seq., and 1874, p. 773. 



Roy. Belgique, 1842 and 

 Unters. Heft i., 1855. 



