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piliferous at the apex ; so close indeed is the resemblance in habit that M. D’Urville has remarked, “ Je possède
un e'chantülon de Gaudichaud, double de taiEe, et voisin de notre L. davatum.” Such being the case, should L.
dmatum he seen to vary in this respect, and especiaUy if it is found to inhabit aU intermecUate latitudes between
its northern habitats and Fuegia, we shaU be obUged to conclude either that the plants are the same, or that L. ma-
gellmúcum may be so sportive as to assume a form undistinguishable from tbe European plant. The former of these
conclusions is generaUy admitted in such cases. The Umits within which a species varies are acknowledged to he
wider in one locality than in another, and two closely allied individuals may he modified almost infinitely without
nuudng into one another, as it is caUed; but, since the knowledge of specific difference is Umited to the powers of
observation, which are only attainable by the microscope, we are forced to acknowledge it possible that two totally
ditferent plants, inhabiting widely separated countries, may present to our senses a precisely simUai- appearance and
remam nndistinguisbable ; a conclusion which, if acted upon without caution, would lead to the subversion of aU our
confidence in wbat are universaUy confessed to be weU estabUshed species.
The acute-leaved hycopoiia, which are not pUiferons at the apex and otherwise closely aUied to the L. mayd-
lanieum, are L. fastigiatum, Br., and L. Piclihidieme, Hook. (Ic. PI. t. 85). the latter certaiidy is, and probably the
former also, a state of or identical with this ; both of them, though inhabiting a lower latitude, are only found at a
great height. From Owyhee we have L. heteropliytlum. Hook. (Ic. FU. 1 .113), in which the leaves ai-e some of
them simply acute as in the more southern form, but others pdiferons and cDiated or erose at the margin, the fonner
a very constant character in the L. cUvatum, and the latter sufficiently obvious in some states only of that plant ;
in other respects this is not to be distinguished from the above or from a very common Chdian species, whose leaves
have long acuminated points, and which seems identical with the X. dendmmrpliim, Kunze ; of this, however, I
have only seen barren specimens, evidently passing into the X. aristatum of the tropics, a very widely diffused and
generaUy acknowledged variety of X. clavatum. Many states of X. cUmtum. are enumerated by Mr. Spring, in his
account of the Brazdian Lyccpodia, (rid. Eegenshnrg Flora, 1838).
The last named author seems to have described from copious suites of specimens, and to bave mrived, in most
points, at the same conclusions with myself; thus, he has found it necessary to combine the X. alopecuroides, L. and
X. longipes. Hook, and Grev,, with X. itmndatnm, L.. to which must be added X. Uathmsii, Hook. (Ic. H. t. 26),
and perhaps X, contextum. Mart. (Fl. Bras. Crj-pt, vol. i, p. 38, t. 23, f. 1.), these species I had considered as merely
forms of one, before Mr. Spring’s paper was pointed out to me. The X. caroliniamm, L., accompanies the last mentioned
species throughout the temperate and warm parts of the American continent, and has also a very wide range
through other countries, having been found in Tropical and South Africa, the East Indies, Madagascar, Tasmania, and
New Zealand ; these two constitute part of a natural section alUed to the Clavatum gi-oup in the spiked, more or less
pedunculate fructifications, and ascending direction of the leaves on the prostrate stems, and to the Complanaium
division in the tendency of the leaves of X. carolinianum to become distichous and decurrent, the other species of it
are X. sdaghwides, L. and L. pygmmru, Kaulf. A third group of species, which, Uke the former, have cylindrical
spikes, contains—1. the X. ammlimtm, L,, a species spread over aU temperate and Northern Europe. Asia, and
especidly America, where it is found as far south as the AEeghany and White Mountains. There arc what appear
barren specimens of this in Hook. Herb, from Dr. Wadicb, under the MS. name of X. Beyneamm. In South
America X. amiotinum is represented by a more slender but very nearly allied plant, w'hose spikes are sometimes
bifid and spuriously pedunculate; it is Hartweg’s 1474 and 1479 from Colombia, where it has also been gathered
by Professor Jameson.—2. X. diapjiantim, Sw.. this is a Tristan d’Acunha species, very distinct in the form of the
scales of the spikes and long piliferous apices of the leaves.— 3. X. sericeum, Mst., this is the X. scariosum. Hook.
(Ic. PI. t. 8 7 ,B0ie), from Pem, one of the most beautiful species of the genus. I know of no others very closely aided
to these, they rank near the Clavatum group, from which indeed they only differ in the tmly sessde spikes, and also
approach that containing X. complanaium, through X, alpinum, whose spikes are sessde.
The X. cemuum, L., may be considered as the type of another natural section, it is perhaps the most abundant
species of the genus, throughout the tropics especially, probably covering more space than any two others. There
are specimens from no less than fifty different stations and seventy collectors, preserved in the Hookerian Herbannm ;
its northern limit seems to be lat. 39°, where it is found in the Azores Islands, and its southern the Capo Colony;
this. like several other very widely diffused species, does not inhabit the Austraban continent, so far as I am aware.
The following species should rank with it,—2. L.penduUttum, Hook. (Ic. PI. t. 90).—3. X. tortum, Siebcr. 4. X.
densum, Lab.—B. ? X. dendroideum, MIeh., this species is of rather dubious affinity and should perhaps be more properly
placed in the Complanatum group, the branches being spread out in a flabedato manner, the whole frond very
compressed or plane, and the leaves haring a tendency to become bifarious; the latter are described as “ being 4-6
fariously disposed, with those of the under surface smaUcr than the rest,” (vid. Bot. Misc., vol. ii. p. 386), this is
always the case, but at the same time those both on the upper and lower surface of the branches are appressed
whilst the lateral spread, and the lower are often so smaU as to partake of the nature of stipides. All the species
of the Oermmm group are robust in habit, erect, generally tad, copiously branched with their branches spreading on
all sides ; the spikes are sessde and very numerous, their mode of growth suffices to distinguish them from those ot
tlie Annotinuni section.
The four groups above enumerated contain most of the imbricate-leaved species with uniform capsides
an-aiiged in terete spikes ; they arc I bebeve strictly natural, though aU are not foimded upon characters of equal
value. One species, more neaily abied to some of tbe above than to any of the other great divisions of the genus,
stands very much by itself, the X. Uterale, Br. (Mi-. Brown’s X. diffusum being possibly a variety of.it), in which
the spikes are placed upon such veiy short branches as to appear tndy lateral; m this respect, as in them obscurely
angular form, it approaches some of the distichous-leaved group, but the habit is totaUy dissimilar and the foliage
like that of X. imndatum, var. Alopecuroides.
3. LvcopoDiDJHian'»«, Brown, Proir. p. 163 et auctorum. L. pacliystachyon, Besv. Ericgcl. Meth.
Suppl. vol. iii. p. 544.
H a b . Lord Auckland’s group and Campbell’s Island ; very common in the woods.
Under the fonner species I enmnerated the different groups mto which those of tlbs genus with leaves imbricated
round the stem and terete spikes arranged themselves ; they form, together, one of the large primary divisions
of Lycopodium ; they arc inhabitants of the cold as w'eU as of the tropical parts of the globe, generaby assuming, as
they approach the equator, a larger growth and more robust habit, both the individual species pecnbar to the low
latitudes, and the varieties of those which equaby inhabit the polar regions, being more fidly developed witlnn or
near the tropics. There they are not replaced by the distichous-leaved gi'oup, but under most conditions are equally
abundant ivitli them. Tlu-ougliout ab changes of temperatm-e and varieties of exposm-e, the scales of the spike never
exhibit any tendency to become fobaceous, nor do they possess capsules in the axds of the leaves.
There are, however, other Lycopodia wffiose fructifications are as manifestly spicate as the last, and which
accompany them through ab cbmates, but whose spikes arc angular and the scales not maferiaby different fi-om
the cauline leaves ; these, in passing from a temperate to a warmer parade], graduaUy lose their spicate character,
the capsides appear equaby in the axds of the upper leaves and in the spikes, the latter become gradiiaby reduced
and at length obbterated, when tlie fnictifications are wdioUy axdliuy : under excessive heat and moistiue,
the same effect is produced by the prolongation of the axis beyond the apex of the spike, into a leafy branch,
simdar to the low-er parts of the stem, and at the same time the conversion of the scales into ordinaiy leaves.
A third modification is presented in those wffiose spikes divide or branch. Here there is a blending of the two
divisions Sdayo and Phleymaria, tlirough X. varium and its abies, wldch together, I consider to form one natural
group ; and it is further to be remarked, with regard to them ab, that these modifications of the inflorescence are
not only the effects of latitude and cbmate, but that one species seems to assume ab these appearances in a single
locabty, which in other parts of the globe is invariable tlu'ougli a considerable area ; and that the causes of the change