504 MOSSES AND FERNS CHAP. 



haps Crie may have obtained only the early stages of the pri- 

 mary tubercle. The differences between Phylloglossum and 

 Ly co podium do not seem sufficient to warrant the establishment 

 of a separate family, the Phylloglossese, as Bertrand proposes. 



THE PSILOTACE^: (Pritzel (i)) 



The Psilotaceae include the two evidently related genera 

 Psilotum and Tmesipteris, the former with two extremely vari- 

 able species (Baker ( i ) ) , the latter with but a single one. All 

 the species are tropical or sub-tropical, Psilotum being found in 

 all the warmer parts of the world ; but Tmesipteris is confined 

 to Australia, New Zealand, and parts of Polynesia. The pro- 

 thallium is quite unknown in both genera, but the development 

 and anatomy of the sporophyte of both are now pretty well 

 known. The sporophyte (Bertrand (i, 2); Bower (15); 

 Solms-Laubach (i)), which in its mature condition is quite 

 destitute of roots, grows either upon earth rich in humus 

 (Psilotum triquetrum) , and is evidently more or less sapro- 

 phytic, or it may be an epiphyte. Tmesipteris grows upon the 

 trunks of tree-Ferns, and Bertrand states that it is a true para- 

 site, which, however, like Viscurn or Phorodendron, has not 

 entirely lost its chlorophyll. The plant always consists of two 

 parts, a lower portion consisting of branched root-like rhizomes, 

 which take the place of roots, and aerial green branches which 

 ramify dichotomously. The branching is especially marked in 

 Psilotum, much less so in Tmesipteris. The leaves are small 

 and scale-like in Psilotum, larger and lanceolate in Tmesipteris. 

 The sporangia (or synangia) are bilocular in the latter, trilocu- 

 lar in Psilotum and in both cases borne upon a smaller bilobed 

 sporophyll. 



The development of the sporophyte has been carefully 

 studied by Solms-Laubach ( i ) , who discovered that it multi- 

 plied rapidly by means of small gemmae (Fig.. 292, k) produced 

 in great numbers upon the subterranean shoots. These buds or 

 bulblets are small oval bodies, but one cell in thickness, and 

 showing usually a definite two-sided apical cell. Their cells 

 are filled with starch, and they sometimes remain a long time 

 dormant. These buds may produce others, but usually from 

 each one is produced one, or sometimes more, elongated shoots, 

 which develop into subterranean branches like those from 



