CilAi'. I] CHARACTERS OF THE TROPICAL CLIMATE 237 



ible influence on the facies of the forest, than we ever do in tlie virgin forests of 

 Brazil. There, nothing is to be found comparable with the gaily coloured clumps of 

 the numerous Ilymenomycetes of our forest soil. The first impression which a frcsh- 

 .-omer wandering in a Brazilian forest must receive, is that apparently very few 

 ungi occur there. As a matter of fact this is in reality not the case ; the fungal flora 

 s extremely rich, but the minute forms especially appear in great abundance, and 

 hese are seen only when one looks carefullj' for tliem, wiiile the larger forms for the 

 nost part onl}' occur here and there '.' 



Among Licliciics, the Ascolichenes, at any rate as far as number and size 

 )f individuals go, play a much smaller part than with us. Large tufted 

 orms, such as Usneae, are seen only on high mountains and therefore 

 )utside the megathermic climate. Cora Pavonia, which alone forms the 

 lass of Hvmenolichcnes, is exclusively tropical, and appears to be cos- 

 nopolitan within the tropics. It is found in its various forms of growth, 

 )ut chiefl}- in its proper Cora-form, in abundance on moist soil and on the 

 ark of trees. 



Bryophyta. 



Among Bryoph}'ta, and especially among Miisci, megatherms are rare, 

 nd are represented for the most part by small inconspicuous species which 

 ccur scantily in cool damp situations, and arc quite unimportant in their 

 tfect on the general facies of the vegetation. Much more richly do they 

 ppear in the cool regions of tropical mountains -. 



Pteridophyta. 



Ferns in the tropics develop an extraordinary wealth of form, and var}' in 

 heir dimensions from small moss-like plants to trees. Most of them are 

 ygrophilous and shade-lovers, so that only humid forests show a great 

 ichness in ferns, l^csides. the majority of them are not decidedly mega- 

 hermic, but prefer a climate that is mild, even if it be as uniform as 

 ossible, so that the greatest development of ferns in numbers, especiallj' 

 f their arborescent forms, is exhibited less in the lowlands than in cooler 

 lountain landscapes. 



Three orders of ferns are exclusively tropical, the Gleicheniaceae, 

 chizaeaceae, and Marattiaceae. 



The Gleicheniaceae are repeatedl}' branched in a dichotomous manner ; 

 ley present a very unique appearance, and in contrast with most of their 

 ropical allies, these ferns occupy open sunny situations, and usually are 

 1 large numbers together. This last statement is specially true of the 

 Imost cosmopolitan Glcichcnia linearis (Fig. 116). which is common 

 verywherc. 



The Schizacaccac (for example Aneimia, a xerophilous genus chiefly in 



' Alf. Moller, op. cit., p. 154. - See Sect. IV. 



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