Roots in Bennettites. 
BY 
MARIE C. STOPES, D.Sc., Ph.D., 
Fellow and Lecturer in Palaeobotany , University College , London. 
With Plate XIV. 
T HE object of this paper is to describe and figure fossil rootlets bearing 
root-hairs petrified with remarkable beauty. These rootlets, in 
addition to their beauty, have a twofold interest: (a) because nothing 
appears to be known about the roots of Bennettites , and the rootlets bearing 
the root-hairs now described appear to be adventitious rootlets of that 
interesting genus ; (b) because, though rootlets of various types are among 
the commonest of well-petrified plant remains, root-hairs are excessively 
rare, and there are very few publications in which fossil root-hairs of any 
genus of any geological age are figured. 
The specimens to be described are a number of rootlets, all in one slide, 
in the geological collections of the British Museum (Natural History), 
No. V. 10158. The area of the plant material cut in this slide is roughly 
5 x 5-5 cm., and the specimen is described in the catalogue as being 
Bennettites , cf. Saxbyamts . The section passes obliquely through cortex 
and leaf-bases, and there is no doubt whatever that it is of Bennettites . 
From the general colour, texture, and other trifles which guide one accus- 
tomed to the few specimens of this genus which are known in this country, 
there is every indication that the slide has been cut from Saxbyanus , though 
there is no record from which block it was cut. It is an old slide, and its 
early history is lost. 
Permeating the Bennettites ground-tissue, which is locally broken down, 
and crossing the mineral gaps, is a large number of stout rootlets, each 
averaging about 1 mm. in diameter. These run in various directions, and 
some are traceable for distances of from 1 to more than 3 cm. in oblique 
lengths. The tracheal and cortical tissues are complete in a number of the 
rootlets, but their chief feature is their root-hairs. These are excessively 
numerous, as can be imagined after inspection of PI. XIV, Figs. 1 and 3. 
Where there is a break in the tissues of the leaf-bases and the rootlets 
[Annals of Botany, Vol. XXXI. No. CXXII. April, 1917.] 
