CONTRIBUTIONS TO BOTANY. 
141 
great elevations ; the latter genus is only found in torrid regions. 
Ephedra consists of shrubs of small height, ramifying from the 
root into numerous divided branchlets resembling those of Ca- 
suarina or Equisetum] these are woody, terete, striated, and 
divided by articulated nodes, each node being surrounded by a 
short vaginant sheath cleft more or less deeply into two opposite 
(more rarely into three equidistant) segments, which form the 
rudiments of leaves, and it is from the axils of these segments 
that other branchlets originate. These branchlets are somewhat 
erect or spreading, and again subdivide in like manner ; but the 
last of them are generally entire, often virgate, though still 
marked by the usual sheath-bearing nodes, and it is from the 
latter that the flowers make their appearance. The inflorescence 
in Ephedra is in the form of a short amentiform and often pedi- 
cellated spikelet arising out of the nodes just mentioned or at 
the termination of short axillary branchlets. The flowers are 
described by authors as either monoecious or dioecious ; but in 
the male spikelets I have generally found, in the terminal invo- 
lucel between the last two male florets, a single female floret 
consisting of its own involucel and a small bifid perigonium 
which encloses two very minute collateral carpels equal to it in 
length : whether these are the same that produce the fruit, or 
are sterile ovaries, I have not the means of determining; in 
either case the spikelets may be said to be polygamo-monoecious. 
The male spikelet is composed of about six or eight involucels, 
each of these consisting of two opposite leaflets united at their 
base into a short vaginant sheath that surrounds the axis ; and 
these involucels, separated by short intervals, are placed decus- 
sately over one another, so that the whole assumes the appear- 
ance of an amentum of four lines of closely imbricated braets. 
Each involucel contains two opposite male florets seated in the 
axils within these bracteiform leaflets, which are erect, ovate, 
concave, and of thin texture, but which afterwards grow to a 
much larger size, and become either scarious or fleshy: each 
male floret consists of a petaloid perigonium, which is nearly of 
the length of the involueel, transversely compressed, tubular in 
its lower moiety, and cleft above into two semiorbicular, erect, 
concave segments with inflected margins, the posterior lobe 
overlapping the anterior lobe imbricatively in aestivation; this 
perigonium is thin in texture, of a pale-yellow or whitish colour, 
the lower pair of florets becoming caducous before the upper 
pair open, the persistent leaflets of the involucels increasing 
gradually at the same time. The stamens are monadelphous, 
the filaments being united into an erect, flattened, narrow, hollow 
tube, with nervures corresponding in number to the anthers ; it 
is about half as long again as the perigonium, to the bottom of 
