336 THE AMERICAN JUNIPERS OF SECTION SABINA. 
IV. THE AMERICAN JUNIPERS OF THE SECTION SABINA. 
FroM THE TRANSACTIONS OF THE ACADEMY OF SCIENCE OF St. Louis, VoL. III., pp. 1-10 oF REPRINT IssUED IN Dec. 1877 
THE species of our Junipers, are, on the whole, well enough recognized, but their scien- [583 (1)] 
tific definition is very insufficient — the characters given in the books, vague and indefinite. 
I have had a good opportunity to study the different species and forms from all parts of our 
country, fresh and living as well as preserved in numerous collections ; among them those contained 
in the great Herbaria of New York and Cambridge (Torrey and Gray) and those of Kew (Hooker), 
and especially those of Berlin, whence the types of the different Mexican species were sent to me by 
my late excellent friend, Alexander Braun. 
With the exception of Juniperus Sabina, which with us is always a prostrate plant, all our 
species occur both in the form of low shrubs and of trees, a few of them of magnificent dimensions. 
In the arid mountain regions, the trunks of the different species which occur there frequently assume 
peculiar conical forms, very thick at base and rapidly tapering to a slender point. 
The BARK is in most species thin, fibrous, and at last detached in shreds; only in J. pachyphlaa 
it is 1-3 inches thick, cracked like that of some oak or chestnut, the surface at last peeling off in 
thin layers. 
The woop is fine-grained and compact, but not always hard; its growth is very slow, so that 
trees of 200 years have a diameter of 4—6, or, in the species growing in more generous soil and a 
more favorable climate, of 12-18 inches. Therefore, when we hear of mountain forms (necessarily 
of slow growth) having near their base a diameter of 3 feet, we cannot help estimating their age? 
at a thousand years and upwards. In J. occidentalis the annual rings are often quite eccentric. The 
resin is confined to the cambium layer and the inner bark; the wood is quite free from it but 
extremely durable, and, at least in J. Virginiana, almost indestructible. In this specie 
the heartwood is red (hence the name Red Cedar) and very aromatic, soft, and splitting [584(2)] 
easily ; in J. Bermudiana it is said to be similar but harder; in all the others, the wood o 
which I could examine, it is paler red or yellowish, harder and less fragrant ; they split less readily, but 
are, in the regions where they abound, not rarely the most available and highly esteemed firewood. 
The LEAVES of young plants or of vigorous shoots are, it is well known, acicular and arranged in 
alternating whorls of threes (rarely in twos), quite similar to the permanent leaves of the Junipers of 
the section of Oxyeedrus, but the older and especially the fertile plants have very short, mostly 
closely imbricate, almost scale-like leaves, the lower part more or less adnate to and forming part of 
the branchlet itself. These leaves occur in some species in pairs, in others usually in threes, so as 
to form 4-sided or 6-sided branchlets, but this arrangement is not constant and ought not to be much 
relied on for specific characters, The leaves bear their stomata on the concave, upper, appressed 
side ; the lower, convex side or back has no stomata, but is marked by a more or less distinct, either 
prominent or sunken “gland,” as it is called,—the dorsal and only resin-vesicle or duct of the leaf. 
This is globose or oblong according to the shape of the leaf, or rarely (in J. Bermudiana) elongated, 
and lies in some close to the epidermis, or is in others separated from it by a layer of parenchyma- 
tous cells. The contents of this resin-vesicle are in some species or in some localities excreted 
through the epidermis, and are apt to appear on the back of the leaves as an aromatic balsam, and, 
later, as condensed resin. 
The edges of the leaf are rarely entire, mostly delicately denticulate, or irregularly fringed with 
minute, corneous, often curved processes. This character permits us to distinguish species where 
others may fail. 
1 This is also alluded to in a letter Sayers after the above was in type, from Sir J. D. Hooker, who had just returned 
from an exploration of our western mountain regions, in which he speaks of the ‘‘ stupendous age” of their Junipers, meaning 
probably J. occidentalis. 
