Studies in the Phylogeny of the Filicales. 
I. Plagiogyria. 
BY 
F. O. BOWER, Sc.D., F.R.S. 
Regius Professor of Botany in the University of Glasgow. 
With Plates XXXII and XXXIII and five Figures in the Text. 
F ROM very early days the position of the annulus of the sporangium 
has been held to be a character of the first importance in the 
comparative treatment of Ferns. In the year 1800 both Bernhardi 1 and 
Swartz 2 had introduced features of the annulus as defining the larger 
divisions of the family, but it remained for Bernhardi 3 later to distinguish 
under the names Helicogyratae and Cathetogyratae the Ferns respectively 
with oblique and with vertical annulus. This distinction was adopted by 
Presl in his ‘ Tentamen ’ of 1836 (p. 20), and he made the oblique 
annulus the character of his first sub-order, while the vertical annulus 
characterizes the second sub-order of Ferns in his system. Presl’s classi¬ 
fication was further adopted by Sir William Hooker in his ‘ Genera Filicum ’ 
(1842) ; it is embodied in the synopsis at the conclusion of that work, with 
the remark that it is ‘ the most full and complete that has yet been 
published But, on the other hand, Kunze 4 criticizes Hooker’s neglect 
of exact detail of position of the annulus in some of his figures, and praises 
Schott (‘Genera Filicum1834) for his accuracy in delineation of the 
annulus; he points out the higher degree of organization of the stomium 
in the Cathetogyratae than that usual in the Helicogyratae. 
It is in the paper of Kunze just quoted that the first description is 
given of any species of the genus now recognized under the name of 
Plagiogyria ; he found in the Ferns described as Lomaria niponica and 
euphlebia a condition different from that of all Polypodiaceae, uniting the 
type of annulus having a highly organized stomium with the oblique annulus 
1 Bernhardi, J. J.: Schrader, Journal fiir die Botanik, ii, 1800. 
2 Swartz, O.: Schrader, Journal fiir die Botanik, ii, 1890. 
3 Dritter Versuch einer Anordnung der Farrnkrauter. Schrader, Neues Journal fiir die Botanik, 
1806. 
4 Pteridologische Studien. Ueber eine noch unbeobachtete Form der Sporangien ( Sporangia 
plagiogyrata). Bot. Zeit., 1849, p. 865. 
[Annals of Botany, VoJ. XXIV. No. XCIV. April, 1910.] 
