156 
CONTRIBUTIONS TO BOTANY, 
With the Myricacecs, Ephedra agrees in many points of struc- 
ture, the most prominent of which are, its diclinous flowers in 
amentiform spikelets; its bract-like involucels; its two-lobed 
perigonium ; its raonadelphous stamens ; its simple ovary, with 
a single, erect, atropous ovule ; its one-celled fruit, with a soli- 
tary erect seed ; and its embryo with a superior radicle. Myrica 
differs, however, in its habit ; its alternate leaves ; its peri- 
gonium in the form of two hypogynous scales, which remain and 
become agglutinated to the fruit ; in its more distinct stamens, 
with anthers bursting longitudinally ; in its two stigmata ; and 
in the want of albumen in the seed. Although these points 
show a considerable interval in the positions of these two fami- 
lies, it is still evident that a notable degree of approximation 
exists between the Gnetacece and Myricaceae. 
The Gnetacece, in their jointed stems and floral structure, oflFer 
many points of approach to the Chloranthacece, Piperacea, and 
SaururacecE •, but the absence or depauperation of floral envelopes 
in those families, and the presence of a vitellus or embryoniferous 
process which surmounts the albumen, of which we find no trace 
either in Gnetum or Ephedra, are features which well characterize 
the above families as a peculiar group, having little connexion 
with the Gnetacece. 
wing ; the lower moiety is thickened and smooth, consisting of an inter- 
mediate mesocarp filled with copious, white, spiral thi-eads, and a testa- 
ceous, brittle, obpyriform eudocarp, completely 1 -celled and indehiscent, 
and containing a single erect seed, which tapers to the apex. This seed 
consists of two verj' delicate translucent membranaceous tunics : upon the' 
outer one (testa) is seen, imbedded in it, a thickened simple cord (raphe), 
by one extremity of which the seed is attached to the bottom of the cell ; 
this eord rises to near the middle of the integument, when it becomes 
suddenly recurved do'ivnward for a short distance, where it terminates in a 
darkish areole (chalaza) ; before its recurvature it throws out a short lateral 
branch or free thread, which serves as the medium of attachment of an 
abortive ovule at a point a little above its base, where this also is recurved 
upon its basal chalaza. The abortive ovule, tapering upwards, is nearly 
half the length of the fertile seed to whieh it is thus attached ; it is deh- 
catelv membranaceous, darkish brown, without the trace of any embiy'O 
within it. Upon the outer integument of the fertile seed, the white cord 
continues to ascend from the point of its furcature, and terminates in the 
apical micropyle, w hich is much darkened. There is no trace of any albu- 
men within the integuments ; and the contained embryo, which is not half 
their length, floats loosely in the upper part of the vacant space, generally 
with the radicle pointing to the micropyle, or at other times lying obliquely 
across the vacant space. The cotyledons are oval, flattened, and foliaceous, 
with a superior terete radicle of about half their length. 
It will be seen that there is very little analogy in the whole of this sin- 
gular structure to Ephedra ; and although the orthotropous embryo lies 
atropously in regard to the hilum, it is amphitropous in respect to the 
chalaza. 
