On some Climbing Davallias 1 and the Petiole 
of Lygodium. 
* , - ... i «. . 
BY 
D. T. GWYNNE-VAUGHAN. 
With Plate XIV and eight Figures in the Text. 
R ECENT studies in the structure of the earlier fossil Filicales have lent 
considerable support to the theory that all the different forms of 
petiolar trace in the group are to be derived from a single primitive and 
ancestral type. This hypothetical trace is imagined as more or less round 
or elliptic in section, with a solid central mass of xylem of the same outline, 
and possessing originally a single mesarch protoxylem. 
It has been shown how both the Osmundaceous 2 and the Zygopterid 3 
type of trace can be derived from this primitive form, and recently 
M. Paul Bertrand has shown 4 that the Botryopterid type may also be 
derived from it, and, directly or indirectly, the Anachoropterid type. 
As regards the living orders of Ferns, it seems probable that their 
petiolar traces are all variants of the Osmundaceous type with the form of 
an adaxially curved C. The traces of the Polypodiaceae, Cyathaceae, and 
Gleicheniaceae conform fairly readily with this type, and, in spite of certain 
difficulties, so it is believed will those of the Hymenophyllaceae and 
Marattiaceae. In the Schizaeaceae Aneimia provides us with examples 
of very typical C-shaped traces, but, according to the text-books, those 
of Lygodium and Schizaea are of quite a different type, and in no way 
related to the C. 
1 [The only species described in the notes is D. fumarioides, material of which was obtained 
from Bath, Jamaica, where it was collected by Professor Bower. It belongs to a group of species 
(Nos. 75-9) placed together by Hooker in the Synopsis Filicum, and characterized by * fronds several 
feet long, usually climbing ’.] 
2 Gwynne-Vaughan and Kidston : On the Origin of the Adaxially Curved Leaf-trace in the 
Filicineae. Proc. Roy. Soc. Edin., vol. xxviii, Part vi, 1908, p. 433. 
3 Kidston and Gwynne-Vaughan : On the Fossil Osmundaceae, Part IV. Trans. Roy. Soc. 
Edin., vol. xlvii, Part iii, 1910, p. 469. 
4 Paul Bertrand : L’etude anatomique des Fougeres anciennes et les problemes qu’elle souleve. 
Prog. Rei Bot., vol. iv, 1913, p. 182. 
[Annals of Botany. Vol. XXX, No. CXX. October, 1916. ] 
