408 West. — A Contribution to the Study of the Marattiaceae. 
Orientation of 
Organization of 
Orientation of Organization of 
Shoot. 
Shoot. 
Shoot. 
Shoot. 
Marattia 
Vertical 
Radial 
Radial 
Radial 
Macroglossum 
>> 
yy 
yy 
A rchangiopteris 
»(?) 
» (?) 
»,(?) 
f j 
„ (?) 
Angiopteris 
yy 
” 1 
Obliquely ascending, < 
1 >5 
Dorsiventral 
1 
[ or horizontal | 
! 
Danaea sijnplicifolia 
yy 
yy 
Radial 
Radial 
r 
„ nodosa 
yy 
yy 
™ ! 
\ 
Obliquely ascending | 
1 
„ alata 
yy 
yy 
Horizontal 
Dorsiventral 
Kanlfussia 
Dorsiventral 
•n 
Two main factors can be recognized as having played an important 
part in the evolution of the wide range in form of the Marattiacean stem, 
namely (i) the remarkable megaphylly of these plants and (ii) the complete 
absence of stereome (other than isolated ‘ stone ’-cells) in their stem-tissues. 
In every genus the adult fronds are relatively large and require a large 
surface for their attachment, although it should be remembered that in 
many species comparatively few leaves are unfolded at once, and that 
these leaves are confined to the apical region of the stem. In this respect 
the Marattiaceae and Ophioglossaceae show close agreement. 
In order to support, and also to supply sufficient surface for the 
attachment of the large fronds', it would be necessary for an upright stem 
to become greatly elongated, in which case a development of stereome 
(such, for example, as we find so well exemplified by the V-shaped bands of 
sclerenchyma that occur in the stem of certain tree-ferns) would be essential. 
It is probably for this reason that none of the existing Marattiacean Ferns 
has adopted the ‘ tree ’ habit. The nearest approach to this type of stem 
is found in Danaea nodosa and Danaea elliptica , where the comparatively 
massive shoot assumes either a vertical or an obliquely ascending growth, 
and largely depends upon the stout adventitious roots for its mechanical 
support (PI. XXII, Fig. 8). 
While still retaining a strictly radial organization of the shoot, three 
genera of Marattiaceae (e. g. Angiopteris, Marattia , and Macroglossum) 
have adopted the squat, massive type of stem, which not only offers an 
extensive superficial surface for the attachment of the leaves and roots, but 
also relegates to the substratum the task of bearing the greater part of its 
weight. In these genera the roots act as stays and assist in keeping 
the plant anchored to the soil. 
The most economical solution of this problem, however, is found in 
the relatively slender horizontal rhizome ; here again the soil to a great 
extent relieves the stem of the necessity for supporting the weight of the 
leaves. This type of stem occurs in most species of Danaea (e. g. D. alata , 
D. Jenmani , &c.), in Kanlfussia , and sometimes in Angiopteris . With 
