59 



and is spread throughout Java between 50 and 3000 m. above sea- 

 level. Elsewhere in the Archipelago it occurs also beneath 50 m. 

 The only specimen collected by T r e u b on Krakatao is very poor 

 and hardly 20 cm. long. P e n z i g records this species also for the 

 trip of 1897 but in the Buitenzorg Herbarium there is no specimen 

 collected in that year and Raciborski 1) does not mention it for 

 Krakatao. This, of course, by ;; po means proves that it was not found 

 in 1897, but we may safely infer that this most conspicuous and 

 easily recognizable fern was not numerous in the localities then 

 investigated. After 1897 Pteridium was never found back on Krakatao 

 what may be sufficiently accounted for by the fact that this part 

 of Krakatao was no more thoroughly investigated but perhaps may 

 be also caused by the high CaO-percentage (2,88 3,36%) of part 

 of the eruptive products -). 1 do not think it probable that in 1886 

 this fern took a large part in the vegetation of the island; if such 

 had been the case, it would also have been numerous in 1897, when 

 the character of the flora was practically the same as in 1886 ;! ) and, 

 if so, Raciborski would certainly have collected and mentioned it. 



10. Pteris marginata Bory. 



At the present time named Pteris tripartita Sw. This is a shallowly 

 rooting halophobous terrestrial fern of sunny or slightly shadowed 

 humid localities, spread throughout Java from the plains up to an 

 altitude of 1200 m. The reproduction is effected exclusively by 

 spores. Raciborski'') calls this plant: ,,Ein haufiger Erdfarn an 

 ,,feuchten, nicht sehr schattigen Stellen der Ebene". For such-like plants 

 the soil of the lower parts of Krakatao was in 1886, generally speaking, 

 rather unfit; the specimen, collected by T r e u b at Zwarte Hoek 

 (as appears from the accompanying label) was still young, perhaps 

 it was an unicum. If large specimens had been present, the very 

 conscientious Treub would have collected them. In 1897 this species 

 was not found back; hence it is improbable that in 1886 it took a 

 large part in the vegetation, because the fern-vegetation in 1897 had 

 practically the same character as during the expedition of Treub <! ). 

 Neither was Pteris tripartita afterwards found on Krakatao. 



l ) Die Pteridophyten der Flora von Buitenzorg (1898), pp. 156, 157 (under the name 

 of Pteris aquilina L, 



' 2 ) Verbeek, KraUatao (1888) p. 292. To local presence of much CaO in the 

 eruptive products points also the occurrence in 1906 of the moss Bryum coronatum 

 Schwaegr. Cf. Chapter VIII. 



3 ) Cf. p. 32, footnote 2. 



4 ) Die Pteridophyten der Flora von Buitenzorg (1898), p. 158 under the name of 

 Pteris marginata Kvr. 



