Boodle. — Anatomy of the Gleicheniaceae. 731 
leaf-trace, but the phloem-fibres are found after the solenostele 
has become closed. In this node moreover a few phloem- 
fibres occurred in connexion with the two protoxylem-groups 
next below those concerned with the leaf-trace, but the proto- 
xylems in the lowest pair of xylem-lobes (in Figs. 26 and 27) 
were not accompanied by any such fibres. From this it 
appears that the phloem-fibres may be continued (as in this 
specimen) from one node to the next, and that the two lowest 
lobes of the xylem serve for the attachment of roots only, 
while all the other protoxylems are connected with leaf- 
traces, which are therefore probably tristichously arranged, 
the node described being one that bears a median leaf. 
Fig. 28 represents a scalariform tracheide of this species, 
and shows a peculiarity in the arrangement of the pits, which 
is rather common here. 
Gleichenia, root. 
The roots of Gleichenia are commonly tetrarch, and rootlets 
of G. circinata , var. longipinnata , were found to be diarch and 
triarch. Russow (’ 72 , p. 97) describes the roots of G. poly - 
podioides and G. glauca (= G. polypodioides , Sm., or perhaps 
G. longissima , Bl.) as being triarch and pentarch respectively. 
The stele of the root of G. circinata , var. microphylla , is repre^ 
sented in Fig. 29. The four protoxylem-groups are seen 
in contact with the pericycle, which varies from one to two 
cells in thickness. Only one of the four phloem-groups is 
shown in the drawing ; its protophloem is at pph. Two 
of the large scalariform tracheides are incompletely differen- 
tiated (y.t.). A root of G. dicarpa had a structure, which 
at first sight appeared to be normally triarch, but, although 
there were only three groups of phloem, one of the proto- 
xylems was split into two groups of small peripheral tracheides, 
which were separated by two parenchyma-cells. This struc- 
ture probably signified that the root was tetrarch in one 
region and triarch in another. 
At any rate in certain cultivated specimens, arrested roots 
