Contributions towards a Knowledge of the 
Anatomy of the Genus Selaginella. 
BY 
R. J. HARVEY-GIBSON, M.A., F.L.S. 
Professor of Botany in University College , Liverpool. 
With Plates XX and XXI. 
Part IV. The Root. 
T HE most important contribution to our knowledge of 
the anatomy of the root-system of Selaginella is that 
contained in Nageli and Leitgeb’s well-known monograph (2). 
Hofmeister, it is true, makes a brief reference to the subject (1), 
but confines his remarks to certain general points with regard 
to the origin and branching of the roots. He speaks of adven- 
titious roots arising at the forkings of the stem in such species 
as V. denticulata , Helvetica , Martensii , &c., either generally 
throughout its length or on the basal region of the stem only. 
The root, Hofmeister says, arises in the axil of the ventral leaf 
situated at the forking of the shoot axis, and from the outer 
side of the cross-band which unites the vascular systems of the 
two branches (e. g. in 5. denticulata). The roots branch freely, 
the first forking being in the plane of the leaf in whose axil 
the root arises, and the second branching being at right angles 
to the first. Hofmeister also draws attention to the swelling 
[Annals of Botany, Vol. XVI. No. LXIII. September, 1902.] 
