41) 
the very moist rain forest and uiossy forest, \v]ierc the rlazonio and roots 
are inibedded in enougli other vegetation to l)o ^itiuitcd as if they were 
in the soil itself, articulations cease to be necessary, and their disuse and 
eventual disappearance can be observed, usually in ferns with snrill 
fronds, in many different groups of ;^pecies: In tlie P. ciuallalum y;rou[t 
'and in Acroso7'ns; in P. pediculainm and P. macriim, with nuuiy artic- 
ulate relatives; in P. caespitosum and some other species of "Gram- 
mitis;" and in the Pa nay species, P. Yoderi'^^ but not in P. tenuisecUtm. 
On the other hand, a Luzon Phyinatodes, P, Proteus, growing among 
rocks on arid ground^ has articulate pinnse as well as stipes. Loxo- 
gramme is probably an offshoot of Eu-Pohj podium, winch 1ms developed 
a decidedly xerophytic structure with or after the loss of articulations. 
Of the San Eamon Achrostichece, U\o are terrestrial and nonarticulate, 
the other is high-scandent with articulate pinna\ 
r 
KHIZOME. 
The stems of Pohjpodiacece are moderately modified in adaptation 
to a wide range of conditions — more modified and more variously 
so than one might imagine from text-book comparisons with I'Jqiii- 
Hetum and the Lycopodinem. The most primitive form of fern stem 
is probably a short, erect one such as is observed in Aspidium, Diplazium 
and Pteris. This may be subterranean, or barely superficial, or, in damp 
and darker places, may rise into the air, as is the case in most of the 
large Diplazia, in Callipteris esculenta, and notably in the huge variety 
of Aspidium leuzeanum. Blechnum Fraseri, of Luzon -'^ and Xcw Zea- 
land, is remarkable among Philippine Polypodiacew for its tall and 
graceful stem. On trunks deeply covered with vegetation, some small 
ferns have stems sta'nding out radially, with a dense, apical tuft of 
small fronds. Among these are Yiitaria minor, and all the Polypodia 
with nonarticulate stipes. A large number of ferns lift the fronds 
above competition with their terrestrial neighboi-s by assuming the scan- 
dent habit. Such are Nepkrodium 1712, all scandent species of Lepto- 
cliilus, Artliro pteris, Nephrvlepis volubxlis, all scandent Lindsayw except 
L. gracilis,. Asplenium epiphyiicum, Lomagrnmwa, and StenocJdaena. 
The majority of these maintain their connection with the ground, hut 
are still, if we classify all ferns as cither terrestrial or cpipliytic, ratlut 
to be regarded as belonging to the latter class, because of their exposure. 
Numerous other ferns keep to the ground or to tlieir original aerial 
support, but remove their leaves from competition with one ajiolhcr by 
a creeping habit and by bearing them at considerable intervals. Neither 
the geotropism of the stem, determining whether it shall be prostrate 
-'This Journal (lOOG), 1: Suppl. 101. 
» Christ: Bull. Herb, BoUaicr (1898), 7, 140. PL G. It is usually more 
slender than this figure shows. 
50146 
mu.Bot*Garaen 
1908 
