IN PTERIDOPHYTES 21 
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Ophioglossaceae, as in the Marattiaceae, the upright radial shoot is 
primitive, and the dorsiventral character of the shoot derivative: that in 
Helminthostachys, as in Danaea and Kaudlfussia, all of them heavily-leaved 
forms in proportion to their relatively elongated stem, the axis has become 
horizontal. 
The Leptosporangiate Ferns present a more varied and difficult problem as 
regards the symmetry of the shoot. They include many upright radial forms, 
such as Cyathea, Alsophila, or Osmunda; as well as many which show various 
degrees of obliquity of the axis, accompanied by corresponding degrees 
of dorsiventrality. It is not an uncommon thing to find upright radial 
Naked-eye drawing of rhizome of Helminthostachys seylanica. F=stipular flap; R=root ; 
L=leaf; P=petiole; LS=leaf-scar. (After Farmer and Freeman.) 
species, and straggling, dorsiventral species in the same genus: for instance, 
Onoclea germanica is radial and upright, Ovoclea sensibilis is creeping ; 
teris aguilina is creeping, while many other species are tufted and radial. 
The same question will arise here as elsewhere, which of the two was 
the primary condition. From analogy with other cases as well as from 
internal evidence, the upright, tufted forms with radial symmetry would 
be held to be the prior type; but the question is complicated by the fact 
that the embryo itself is not upright in the Leptosporangiate Ferns, and 
it may be thought that its recumbent position defines ad ¢nitio the dorsi- 
ventrality of the shoot. 
It is true that the first leaf of the young sporophyte is uniformly on 
the side away from the prothallus: but the position of the second and 
