9 
Evolution o f Branching in the Filicales. 
by Faull. 1 Immediately beyond the bifurcation either each branch 
may possess a complete ring of separate xylem strands (Osmunda 
Claytoniana), or the two rings may be interrupted by ramular gaps 
on the sides facing each other (0. cinnamomea, Q. regalis, Todea 
harbara). 
We have now reviewed the vascular relations between branch 
and main axis in a large number of Ferns selected from nearly all the 
great families in which the branching of the stem has been described 
and ranging in stelar structure from the simplest to the most 
complex type. The results may be briefly summarized as follows:— 
I. In Ferns with a protostelic main axis the branch is also as a 
rule protostelic throughout its length (Hymenophyllacese, Zygopteris, 
Cheiropleuria) Fig. 1, A. 
II. Ferns possessing a tubular stele in the main axis have in 
their branches either a tubular stele throughout their length 
(Marsiliaceae, Lophosoria, Metaxya, Hypolepis, Pteris incisa, var. 
integrifolia, etc., Fig. 1, B) or at the base a solid strand which soon 
becomes converted into a tube ( Hehninthostachys ). 
III. In Ferns which have a reticulate stele in the main axis 
the vascular system of the branch may either 
(a) be from the very base a reticulate stele, which may or 
may not be attenuated towards its insertion to the main stele 
(Osmundaceae, Poly podium spp., Fig. 1, C) or 
( b ) it may start at the solenostelic stage, also often contracted 
at the base ( Adiantum trapeziforme , Cyathea, etc., Fig. 1, D) or 
(c) it may possess at its base the Lindsaya- type of structure 
(Cibotium Barometz, Fig. 1, E) or, lastly 
(d) it may begin with a thin protostelic strand which is of 
variable length (Alsophila excelsa, Aspidium cristatum, A. spinulosum, 
Struthiopteris germanica, Nephrolepis). 
When the main axis contains a medullary system of strands the 
branch may either develop its medullary system independently of 
it, or the two may be continuous through the gap at the base of 
the branch (several Cyatheas, Polybotrya Meyeriana, Matonia). 
In each case except ( a ), the branch, during its growth, passes 
successively through morphologically higher and higher stages, till 
it acquires the type of stele characteristic of the adult main axis in 
that species. 
Faull, Bot. Gaz., Vol. XXXII, 1901, p. 398. 
