208 Bower . — Ophioglossum simplex, Ridley. 
having figured in their past history, or (e) that they are leaves of the 
ordinary Ophioglossaceous type, in which the sterile lamina has become 
entirely abortive ; in the latter case the whole appendage would be of 
a composite nature, the upper part being the spike, the lower part being 
of the nature of a leaf-stalk. A decision can best be approached on an 
anatomical basis, for there is between the sterile leaf and the fertile spike 
the general difference of orientation of the vascular strands : the xylem 
in the former being on the adaxial side, in the latter it is inverted, and 
facing the abaxial side. 
The following notes on the distribution of the vascular strands in the 
leaves of certain species of Ophioglossum may be of use, as a basis for 
comparison. 
In O. Bergianum , Schlecht, the leaf-trace originates, as in all the 
Ophioglossaceae hitherto examined on that point, as a single strand ; 
in most species this single strand branches early, but in O. Bergianum 
it remains at first unbranched. The vascular supply for the fertile spike 
comes off as two lateral bundles from the margins of the leaf-trace ; these 
fuse together to form the single bundle of the base of the fertile spike. 
This single strand may branch as it passes upwards, so that the transverse 
section of the fertile spike may show two, three, or even four strands, 
but they are always orientated with the xylem directed to the abaxial side. 
In the upper region there is only one strand, which passes through the 
rows of sporangia to the extreme tip 1 . The branchings in the sterile leaf 
are few and irregular, but the number of strands commonly seen is three, 
with the xylems on the adaxial side. This is the simplest species of the 
genus structurally, but the leading features are the same in the more complex. 
A slightly increased complexity is seen in O. lusitanicum , where the 
vascular supply of the sterile leaf branches into three, and the supply from 
the spike comes off from the lateral strands (Prantl, loc. cit. PI. VII, Fig. 1). 
In O. vulgatum the origin of the vascular supply of the spike is 
here again as two lateral strands, one from either marginal bundle of 
the sterile leaf 2 . These strands branch again as they pass upwards, 
and five strands usually appear in the transverse section, an arrangement 
which may be very nearly matched by some sections near the base of 
the leaf-stalk ; but the distinction is always easily drawn by their inverted 
position : the xylem of the fertile spike being on the abaxial side. In 
O . reticulatum , L., the arrangement is similar to that in O. vulgatum , 
as regards the fertile spike, and it is probably the type general for the 
ordinary ground-growing species. 
The similarity of O. simplex to O. pendulum in certain external points, 
1 See Prantl, Beitr. z. Syst. d. Ophioglosseen, Jahr. d. k. bot. Gart. Berlin, iii, p. 297. Also 
Bower, Studies in the Morphology of Spore-producing Members. II. Ophioglossaceae, p. 68. 
* See Prantl, 1. c., Taf. vii, Fig. 2. 
