116
ai-e at one time quite latent and at anotliei- conformable to our ideas of tlie effects of temperatiu’e and local circumstances.
I t is not only in the inflorescence tbat tliis gi'oup is liable to vary, but one form passes into others by
the modifications of many of its organs at once, and this to so great an extent as to render it extremely difficult to
define any one species between the two extremely dissimilai* forms of L. Selago and L. Phlegmaria. Want of space
obliges me here to confine my attention to tbe phases under which L. varium occiu's ; these are so remarkable and
were so wholly unexpected, that if we agree to consider such plants to be the same species as only oflnr forms nndis-
tiuguishable to our senses, it will follow that the most of these supposed species must merge into one, and that
Lycopodium Selago is perhaps the most variable plant in the ivorld.
L. varium, in Lord Auckland’s group and Campbell’s Island, is one of the finest of the genus ; it gi-ows nearly
erect on the bare ground, to a height of 1 -3 feet, branching upAvards, copiously leafy, with large spreading leaves,
bearing at the apices of the branches numerous pendulous or drooping tetragonous spikes 3-4 inches long. The
stems of this species are often nearly the thickness of a sAvau’s quill AAuth spreading leaves as broad as the middle
finger ; I have no Avhere seen handsomer specimens of it than this island presents, and more constant ones, for it is
confined to the woods, aud does not ascend the hiUs, neither var\-ing in tlie narroAV belt it inhabits nor seeking other
localities where it would be exposed to the influence of exciting causes. The case is veiy different in Tasmania,
Avhere it also grows veiy commonly in the subalpine woods, and from Avhence I have specimens of Lycopodia presenting
all intermediate stages between tliis and L. Selago, the connecting links being similai* to Avhat have been
considered different species in other parts of the globe. Form and habit alone have not induced me to unite such
dissimilar plants, for I have in vain sought Avith the microscope for diagnostic characters. The smallest Tasmanian
specimens have been published as X. Selago (Hook, and Grev. in Bot. Misc., a'oI. iii. p. 104), they ai*e about tiA'e
inches high, simple at the base, branching upAvai'ds, in all respects similar to the American and Emopean plant ;
they are likewise copiously supplied with gemmæ, giAong a squarrose appearance, these'Avere fii-st observ'cd on the
North-west American specimens of X. Selago, but ai*e now knoAvn to be common on this species even in Scotland,
Avhere a variety occurs Avith small very acuminated leaves, those of the gemmæ being sometimes much altered, broadly
obovate-oblong, acute, and keeled on the back. In the next stage of the Tasmanian plant, the stem ascends from a
curving prostrate base, is about 5-6 inches long, the lower leaves are linear, acute or acuminate, patent or subsquar-
rose, subserrulate towards their apices, obscurely nerved in the middle, the upper leaves are generally appressed for
nearly the whole lengt.h of the stem, lanceolate or ovato-lanceolate, acuminate, acute or subacute, obscm-ely nerved,
the margins cartilaginous Arith obsolete serratxues : this fom is quite identical with others of X. Selago from Cumberland,
as well as with many from North Europe, Asia, and America. The two first described states inhabit exposed
places, the following (the third), which grows on rocky places on the margins of woods, has the stems a foot or
more high, branching, much curved and ascending at the base, spaiingly branched above ; the leaves, except towards
their apices, are patent or subsquarrose, lai-ger and more loosely placed than in the fonner, with the nerve more
thickened, those at the summits of the branches ai*e similar to the leaves of the second state but more distinctly
serrated. X. Selago of Tasmania resembles X. suberectum, Lowe, of Madeira and other wanner pai-ts of the northern
hemisphere, in which the leaves are generally all squanose, nearly entire or strongly ciliate at the margins ; this is
such a fonn as a species, in passing from a colder to a more genial temperature, might be supposed to assume.
In the fourth stage of the Tasmanian plant the leaves become larger, more patent or subreflexed, coriaceous and
shining, still they are more or less acute, and the capsules are Avholly axillaiy, sometimes confined to the middle of
the branch, at others to the upper portion, Avhich looks rather different from the loAver and indicates the transition
to X. varium. This state is nearly allied to some Indian forms of the genus, as also to X. luciduUm, Mich., which
varies in the sen-atures of its leaves and in other particulars approaches very near, if it does not absolutely merge
into American forms of X. Selago. Nor is it to be distinguished from Ceylon and Tristan d’Acunha specimens
of X. insulare, Cann., AA'hich fmdher passes into X, crassum. Hook, and Grev., and through it into some other South
American species.
The remaining Tasmanian states of X. Selago may be considered as belonging to X. varium ; in the fifth of these
(from the small one Avith which I commenced), the stout stem becomes naked below, sparingly leafy upward, Avith
long, linear, coriaceous, acute or obtuse leaves, the capsules are both axillaiy and spicate, but tlic spike is interrupted,
the scales being at one time small, and at another foliaceous. This approaches the X. taxifolium, Sw., aud X. Uni-
folium, L., natives of various parts of the world, also X. gnidioides, L., Cape specimens of Avhich differ fr-om the normal
state of varium only in having axillary capsules, whilst in other localities it becomes pendulous and spicate; and so
with regard to the X. Flagellaria, Bory, of New Zealand, wliich I cannot distinguish, except by its mode of gi'owth,
from X. varium. To dwell at length upon all the varieties of this species would be out of place here, and occupy
many pages; the transitions from it to Phlegmaria are not obscure, the variations of that plant being excessive.
The importance of the question, “ Avhether two perfectly similar plants, from remote quarters of the globe, are
to be considered as belonging to one species,” has induced me to canvass very fd ly the claims of many supposed
forms of Lycopodium to the title of distinct species. In aU such cases, my first object has been to determine
whether the plant inhabits various intermediate countries. MTieu, as is the case Avith Callitriche verna (p. 11.),
Montiafontana (p. 1 3 ,), Gentiana prostrata (p. 56, in note), Myosotis fulva (p. 57, note), and Trisetum subspieatum
(p. 97.), they ai-e found to do so, there need be little hesitation in refeiTing them, after due examination, to one p lant;
in such instances, the supposition of a double creation of tbe same species, or of one of them being a A'aricty of some
other really distinct plant, wliich plant wholly resembles another from other countries, Avould be confessedly a gi-atni-
tous assumption. Where however no intermediate stations can be detected, these suppositions become more plausible
; the oidy alternatives to such conclusions being, 1st, the possibility of the species being destroyed in the intervening
positions Avhich it may formerly have iuliabited; 3nd, the gi-eat improbability that the seed has been earned
at once from one polar region to the other; or, lastly, u'hat I have endeavoui-ed to establish Avith regard to Lycopo-
dium varium and Selago, that the species does exist in all intennediate latitudes, but in a hitherto imrecognised form;
a cii-cumstancc the less to be Avondered at on many accounts, and tbe folloAA'ing in pai-ticular. Oiu- daily increasing
knoAvledge of Ferns proves that the species are infinitely more Avidely distributed than has been supposed. The scA'eral
species being variable in limited areas, it is to be expected that the amount of vai-iation should increase proportionally
Avitli tlie space they cover; because the indiAidual species of many AAudely distributed genera, as Lycopodium, have
often themselves Avdde ranges; because the loAver we descend in the scale, according to which aU knomi vegetable
productions are now arranged, the more universally we find the species scattered over the surface of the globe ; and
lastly, tbe minute size and abundance of the spoi-ules of Lycopodium are favom-able to theii* extended dispersion,
A C O T Y L E D O N E S .
XXXIII. MUSCL
(By Wm WTlson*, E sq. and J. D. H ookeii.)
I . A NDRE.EA, Ehrli.
Theca quadi-ifida, rarius octofida; vahailis apice operculo persistente connexis. Calyptra mitraiformis. Vaginula
upophysiformis, sctam breAnssiinam occultaus, demiun stipitata.
The peduncle, Avhich elevates the niatui'c capsule iu this genus, is nothing more than an elongated receptacle
{pseudopodium, Brid.) of a white coloiu*; such as is also found in Sphagjium. In an early stage, this receptacle scarcely
(lifters in appearance from that of other mosses; by its subsequent elongation the theca is elevated, generally above
* I here most gratefully acbioAvlcclge the invaluable assistance afforded me in the more complete determination,
and in the diagnoses and descriptions, of the mosses, by oui* old and Aulucd friend ‘WiUiam Wilson, Esq,, of
Warrington; Avhosc accinacy in botanical, and especially in microscopical investigation, and knowledge of this
tribe of plants, arc beyond praise.—J. D. II.
X