Boodle . — Anatomy of the Gleicheniaceae. 725 
In the lower part of the petiole of G. circinata a small 
sclerotic group, surrounded by an endodermis 1 , is found in 
the central pericycle, just as in the leaf-trace and petiole of 
G. dicarpa (Figs. 23 and 13). In the case examined, however, 
it nowhere included more than three fibres. It dies out 
upwards in the petiole as in the other species just quoted. 
A node of G. circinata was examined with the expectation 
that the sclerotic group would behave as in G. dicarpa , but it 
was found to be restricted to the base of the petiole, and to 
have no connexion with the cortical sclerenchyma. In the 
node examined, the leaf-trace separated with a closed xylem 
surrounding very little central parenchyma. As the leaf-trace 
passed through the cortex, its central parenchyma increased 
to a triangular sclerotic group, and within this there appeared 
a brown sclerenchyma-fibre, surrounded by an endodermis, 
just about when the petiole became free. The single fibre 
was soon replaced by two and then three, and these were 
reduced to one again, which soon disappeared. * The fibres 
thus had no connexion with the cortical sclerenchyma, but 
formed a thin spindle-shaped group sheathed with endodermis 
and isolated in the central pericycle of the petiolar bundle. 
As the group is so small, and occurs within other sclerotic 
tissue, it is probably a reduced structure, derived from one 
like that found in G. dicarpa . Poirault gives a figure of the 
petiole of a variety of G. circinata ( G . Speluncae) , showing 
a central sclerotic group of thirteen elements, surrounded by 
an endodermis, so in this form the sclerotic tissue is better 
developed, and might be continued down into the node as 
in G. dicarpa , or still further into an enclosed nodal island as 
in Poirault’s diagram of G. hecistophylla , and in G. dichotoma. 
The characters of the node of Gleichenia may be sum- 
marized shortly : in several species a parenchymatous nodal 
island is formed in the xylem of the stele, and contains 
phloem and a group of sclerenchyma (surrounded by endo- 
dermis) ; the sclerenchyma is continued for a short distance 
1 This endodermis contains granular (probably siliceous) bodies exactly similar 
to those occurring in the external endodermis of the bundle in this species. 
3 B 2 
