Studies in Hepaticae: On Pallavicinia 
decipiens 1 , Mitten. 
BY 
J. BRETLAND FARMER, M.A., 
Fellow of Magdalen College , Oxford ; Assistant Professor of Biology at the 
Royal College of Science , South Kensington. 
With Plates VI and VII. 
T HE genus Pallavicinia (Gray), otherwise known as Blytia 2 
(Endl.) or Steetzia (Lehm.), is one which includes rather 
more than twenty species, which exhibit, amongst themselves, 
a considerable range of variation in form. Most of them 
agree more or less with the type as illustrated by P. Lyellii , 
a plant not unfrequent in this country, and which consists of 
an elongated thallus, with a prominent mid-rib. Branching 
may occur dichotomously, or by ventrally-formed shoots. 
But specimens of P. Lyellii not unfrequently depart from the 
more usual form, in so far as the thallus- wings are often 
scarcely developed in the posterior region of the plant, which 
in this part comes thus to consist of little more than mid-rib. 
It is only as one passes to the more anterior portions nearer 
the apex, that the lateral expansions attain their full breadth. 
When however this feature is also accompanied by the forma- 
tion of a few rapidly succeeding dichotomies in the apical 
region, the plant assumes an aspect quite foreign to the 
normal habitus of the species. It is, in these cases, not difficult 
1 This plant was described by Mitten (Joum. Linn. Soc., 1861) as Steetzia 
decipiens. 
2 In the Synopsis Hepaticarum the generic name is given as Blyttia ; though 
Endlicher wrote it as in the text. 
[Annals of Botany, Vol. VIII. No. XXIX. March, 1894.] 
D 2 
