The Lateral Roots of Amyelon radicans, Will., 
and their Mycorhiza. 
BY 
T. G. B. OSBORN, B.Sc. 
Assistant Lecturer in Botany in the University of Manchester. 
With Plates XLVI and XLVII. 
MYELON RADICANS was described by Professor Williamson (22) 
jlJL in his fifth memoir, ‘On the Structure and Organization of the 
Fossil Plants of the Coal-Measures ’ (1874), as the root of Sphenophyllum , but 
has since been shown to be the root of Cordaites. In his description, which 
is mainly concerned with the big roots that have undergone secondary 
thickening, he refers to groups of lateral rootlets. His Fig. 46, PI. VII, 
shows two such bunches of much-branched roots. These are, he says, 
arranged irregularly on the periphery, and not definitely as in Stigmaria. 
As far as I am aware this is the only description of the small roots. 
Solms-Laubach (16) gives a short account of Amyelon , based on that 
of Williamson. The root is given amongst those of uncertain affinity. 
Renault (11) has described the roots of Cordaites , together with other 
parts of the plant from Autun. The species described by him have a diarch 
root, and the periderm forms in the outer cortex. Another difference from 
Amyelon radicans is that in his specimens the phloem is not preserved. 
Scott’s ‘Studies’ (13) also contain a short account of Amyelon as 
the root of Cordaites , but no mention is made by him of the lateral rootlets. 
The periderm is stated by him to be deep-seated in its origin. 
At the suggestion of Mr. D. M. S. Watson, I examined some slides of 
Amyelon , with a view of seeing if these remarkable bunches of rootlets 
might correspond in any way with the 4 root-tubercles ’ of recent plants, in 
which he knew me to be interested. I have found evidence that this 
supposition is probably correct, and that the tufts of short, much-branched 
roots were probably of the nature of ‘ coralline roots \ I wish here to 
express my deep indebtedness to Mr. Watson for calling my attention 
to this point, and for most generously placing his slides, some of which 
he had made for the purpose, at my disposal. The slides on which this 
[Annals of Botany, Vol. XXIII. No. XCII. October, 1909.] 
