Sykes . — The Anatomy and Morphology of Tmesipteris. 65 
in which several aerial stems arose from one rhizome . 1 Usually the 
winding, hairy, and irregular rhizome passes by a more or less straight and 
glabrous transition region into the upright stem. The surface of the upper 
part of the transition region becomes gradually ridged owing to the fact 
that the leaf bases are decurrent. At this stage a number of small scale- 
leaves, varying from two to six, according to the size of the plant, and 
reminding one of the leaves of Psilotum , are given off. Every transition 
is found between these and normal leaves. The latter in T. tannensis are 
from a half to three-quarters of an inch long, while in T. lanceolata they 
may reach one and a quarter inches in length. In the former species the 
largest leaves are found about half way up the stem, and decrease in size 
again towards the apex of the plant. Each leaf is sessile and ovate — 
lanceolate, has a mucronate tip, and is adnate to the stem by its base and 
part of one side. In T. lanceolata the largest leaves are found lower 
down on the stem than in T. tannensis ; they have no mucronate tip, but 
taper gradually to a point, and they are lanceolate in shape. It is doubtful 
whether these two kinds of leaves are sufficiently distinct to warrant in 
themselves the distinction of the forms bearing them as two species ; 
especially as in some cases 2 both kinds have been found on the same plant. 
There appears to be no other important difference between the so-called 
species. 
The leaves are arranged spirally in two to five irregular rows, and are 
vertically placed, like the phyllodes of Acacia. 
(2) Fertile region. In T. tannensis the first branches are formed at 
the region of maximum development of the leaves, in T. lanceolata rather 
above this region. There may be a leaf here and there among the 
branches, but generally the purely foliar regions of the stem are sharply 
marked off from the branch-bearing regions, somewhat in the same manner 
as was noted by Bower in Lycopodium S el ago . 3 In several cases these 
regions were found to alternate, six to eight sterile leaves being placed 
between two fertile regions. No sterile branches such as those described 
by Bertrand 4 and Dangeard 5 were borne on my specimens, but every 
branch was fertile and generally bore two leaves and a bisporangiate 
synangium. 
In some plants growth had stopped, and in these cases the main axis 
ended in a fertile branch or sporophyll, bearing as usual two leaves and 
a synangium. Presumably the apex is here employed in the formation 
of the terminal synangium. In one case the last organ borne by the 
mature plant was a leaf. Other specimens were still growing at the time 
1 Dangeard, Le Bot., ii, p. 168. 
2 Vaughan Jennings and Hall, 1891. 3 Bower, 1894, p. 353. 
4 Bertrand, Figs. 203, 243-6. 
5 Dangeard, Le Bot., ii, p. 181, PI. XII, Fig. 5., and PI. XIV, Fig. 8. 
F 
