74 2 Boodle. — Anatomy of the Gleicheniaceae. 
with the phloem on the inner or upper side of the leaf-trace, 
but may also be continued upwards in the xylem of the 
stem for a short distance after the separation of the leaf-trace. 
In G. pectinata two nodal islands are found, but some of 
their constituent elements may be continued as far as the 
next node. 
7. Platyzoma has a collateral leaf-trace but apparently 
a concentric petiolar bundle. The median protoxylem is 
absent. There is no true leaf-gap. The group of parenchyma 
below the separating leaf-trace contains no phloem or scleren- 
chyma. 
8. The bundle in the midrib of the pinnules shows collateral 
structure. 
9. The roots are mostly tetrarch. Rootlets may be diarch 
or triarch. The roots of Platyzoma are diarch. 
10. The seedling stem of Gleichenia , except for the absence 
of definite protoxylem-groups, attains the typical stem- 
structure of the genus below the insertion of the third leaf, 
and by that time has given no evidence of reduction from 
a more complicated type. 
The most important structural point met with in examin- 
ing the anatomy of this Order, not previously described, is 
the solenostelic structure of one of the species of Gleichenia. 
Our knowledge of this type may throw considerable light 
on the comparative anatomy of the group. 
I wish once again to express my indebtedness and thanks 
to Dr. D. H. Scott, F.R.S., for many valuable suggestions. 
I have also to thank Mr. J. G. Baker, F.R.S., Mr. C. B. 
Clarke, F.R.S., and Mr. C. H. Wright, A.L.S., for giving me 
their kind assistance in one or two points. The material used 
for this investigation was from plants in cultivation in the 
Royal Botanic Gardens, Kew, in the case of several species 
of Gleichenia ; in other species and in Platyzoma only dried 
material was available. Seedling plants of Gleichenia appear 
to be difficult to raise. The one examined was grown at Kew. 
