West. — A Contribution to the Shidy of the Marattiaceae. 363 
Morphology. 
1. Danaea. 
The very young sporophyte of both species of Danaea examined by 
the present writer exhibits a perfectly radial symmetry (PI. XXI, Fig. 4), the 
first few leaves being arranged in a rough spiral on the stem, which is 
relatively elongated as compared with sporelings of Angiopteris , Macro - 
glossum , or Marattia 1 of similar age. 
In the case of Danaea , we find within the limits of a single genus two 
distinct trends of organization. Whereas in Danaea nodosa , Sm.,the radial 
symmetry is maintained in the adult plant, in Danaea alata, Sm., the shoot- 
apex very soon bends through an angle of 
approximately 90° (PI XXII, Fig. 9, A and B), 
and continues its growth in the horizontal 
plane. The stage at which this change in the 
direction of growth of the shoot takes place 
varies slightly in different plants, but it always 
occurs very early. As a result, the adult 
plant of Danaea alata exhibits well-marked 
dorsiventrality, the leaves, which are simply 
pinnate, arising from the dorsal and lateral 
surfaces of the horizontal rhizome, as is shown in 
Pl.XXI,Fig.2. Very occasionally, however, a leaf 
arises from the ventral surface of the rhizome. 
All the leaves grow more or less vertically 
upwards, the bend taking place in the region 
of the basal pulvinus of the petiole. The 
roots, which branch freely in a monopod ial 
manner, 2 arise in no very definite order from 
all sides of the rhizome, but there is usually 
one to each leaf of the adult plant. Prominent 
stipules with distinct commissures occur at the 
base of the petioles and provide a most efficient 
means for protecting the growing apex, the stipule of any leaf completely 
enveloping the next younger leaf whilst the latter is at an early stage in 
its development (PI. XXI, Figs. 5 and 6 ; Text-fig. 1). Moreover, numerous 
peltate hairs or scales occur on the petiole. ! It is worthy of note that those 
Ferns which bear relatively few leaves at a time generally possess highly 
developed protective devices (e. g. Ophioglossaceae ; and cf. Campbell, 20 , 
p P . 1 91-3). 
1 The young plants of Marattia fraxineag>rs\ ., investigated by Kuhn (42) appear to be exceptional. 
2 It is difficult to reconcile this fact with Kuhn’s (43, p. 149) statement that in the case oi Danaea 
alata 1 die Wurzeln scheinen normal unverzvveigt zu sein ’. 
Text-fig. 1. Danaea alata, 
Sm. Transverse section through 
the apex of an old plant, showing 
bud - protection. s.t. = stipule, 
x 4. 
