16 DIAGNOSIS AND CLASSIFICATION
the term is to be applied in the most provisional sense. At the same time it is very
evident from the morphological aceouac of tlie genus how few in number the reliable
diagnostic characters really are.
In the present paper use has only been made of such characters as appear to
be absolutely constant within the limits of the genus. In using calycine characters, for
example, a calyx of which the limbus is cleft has been contrasted -with one of which the
limbus is not cleft at all; no use is made of the extent of the cleavage. And in using
corolline characters a tube dilated towards the apex is contrasted with a tube not there
dilated, the amount of dilatation being considered of altogether subsidiary value. Then
•while the extent of elongation of the tube, as indicated by the relative length of calyx
and corolla, is not used in diagnosis, the portion of tube which elongates, as indicated
by the position of the staminal insertion, is employed. Only a subsidiary value is
assigned to the relative length of the lip when compared with the hood, while characters
derived from its outline (whether with lobes truncate or entire) and from its margin
(whether ciliate or glabrous) have been used as diagnostic. Similarly a high diagnostic
value is assigned to the fact that a beak is present or is absent; also when the beak is
present to the fact that it is lodged in the bud with its apex towards the edge of
the lip or towards the throat of corolla, and to the fact that its apex is entire or not
entire, while only a subsidiary value is assigned to the mere length of beak or to the
extent of its bifurcation when it is bifid. Finally, great value is attached to the condition
of the filaments whether hirsute or glabrous (though when they are hirsute little
weight is attached to the mere degree of pubescence), as well as to the surface markings
of the seeds, which are, as Lange has poiuted out, absolutely constant.' The
fact of constancy, then, is the key to the value of the characters selected; they are
such as appear to be constant not merely for individual species, but for the whole genus.
One consequence of rigid adherence to the principle now explained is that certain
forms usually accepted as specifically distinct are here accorded only varietal rank or
are altogether reduced. Thus P. cabulica BTH. is joined to P. doUchorrhisa SCORENK;
P. Senienowi REGEL to P. pycnantka Boiss.; P. ochroleuca DUTHI B to P. maurantlia
K L O T Z S C H ; P . labdlata JACQUEM. to P. rhinanihoidcs SCHEENK. It does not follow because
this has been done that the characters whereby these forms are separable are not
constant so far as the two particular forms are concerned. The reduction indicates
only that the characters on which it is necessary to rely in order to effect the diagnosis
in these special cases are characters that are clearly not constant in certain other
species of the genus. On the other hand, specific rank has in a few cases been accorded
to forms already recognised as distinct, but hitherto only treated as varieties. Thus
P. aspleniifvUa VA.R. alb<fl')Ta HOOK. F. is here treated as a species apart from
P , aspleniplia FLOERKE, and P. furfuracea VAK. infegrifolia HOOK. F. as a species apart
from P. far far acea WALL., because in these instances the characters by which the forms
are separable are characters which are constant in the genus as a whole.
To this treatment of forms of the latter class exception will probably not be taken,
since it is already certain that the forms are truly distinct. "With forms of the first class
it is altogether different, since the treatment here proposed for them involves a
iiindamental difference of opinion as regards their rank. The reductions involved by the
application of the canon have therefore only been effected in those species that actually
occur within the area dealt with in this paper, because it seems improper to propose such
' Lange, Siaenkov, K^o'jn. But. Tidsk. IT, 2D7, et spq,
GROUPS OF SPECIES. ''
a course without explaining fully, as is done in the notes following the individual specific
descriptions, the reasons for adopting the view that is here published. The nonapplication
of the canon affects, but only slightly, the numbers and proportions in tlie
distribution tables so far as the European province is concerned, since for it the recent
clear and careful account of the European species by Herr Steininger has been closely
followed, and since that author separates as species forms that ai-e capable of differention
only by'characters that a wider study of Siberian, Chinese, and Himalayan ones shows
to be variable within the limits of the genus. For example, P. luBitaniea is specifically
separable from P. sylvatica only by relative characters, and by tho present canon can
only be a variety of the latter; and P. Fridcrici-Augusti, which CarueP declares to be the
same species as P. petiolaris, is kept apart by Steininger® (who cannot understand why
this reduction should be proposed) only by two or three vague differences of habit
and by the different coloui- of corolla, which last, though certainly a striking character,
has not always a really diagnostic value, as the evidence of P. megdantha and some other
species very distinctly shows.
But as Sir J, D. Honker has clearly shown,^ species are by no means units of
equal value. This is especially true of the "species" of Pedicularis, however rigid be
the canons applied in defining them. Clearly species that differ from each other so little
as does P. carnos« from P. corymbosa, or P. CiarUi from P. Prainiana, or P. pohjphyila
from P. tenuisectii—i\Q first of each of these pairs has a beaked, the other a beakless
corolla, while the members of each pair agree so closely as to habit, calyx, capsule, and
seeds that the verbal description of all tliese characters has in both to be identicalare
more closely related to each other than species Hke P. Oederi and P. pyenantha,
which with very similar corollme characters differ in habit so fundamentally that the
first lias alternate leaves with a continuous spiral centrifugal inflorescence, the other
opposite leaves with an interrupted verticillate centripetal spike.
In Pedicularis, as in Thalictrum, in Jlubus and in Sazifraga, this arrangement of tlie
separable forms in evidently natural groups is a characteristic feature. And it is probable
that these groups, rather than the forms here termed "species," constitute the natural
units of the genus. It is therefore of some importance to recognise and define tlie limits
of these groups, since otherwise a system of classification might be adopted that in its
application divorced naturally allied forms. The evidence as to the composition of these
natural "groups" is in many respects the converse of that which enables us to define
" species." In such groups forms that agree in the greatest possible immber of
characters are brouglit together; cnsequently the characters that prove least reliable in
specific diagnosis are those that are of greatest value in distinguishing theui. Habit,
c'ylyx, apd capsule now give useful characters; and it is as indicative of affinity between
allied species rather than as diagnostic of separable ones that seed-character.s are chiffly
• Camel in Parlalore, Flor. JCal, vol. vi, p. 437.
» Steininger in Uhlwartn vnd Behrens, Botan. CentralUait. xxlx, p. 315. Herr Steininger's diagnosis is as follows ;—
s separable from P. FnderUi-Augxisti by its oblique rootstock witli stouter roots, its stem wliieli is
and lias few leaves unevenly disposed, but mostly near the base of the spike, by its diffi-rently-shaped
e longer than the calys, by the colour of the corolla, etc." The writer adds:—It is rery difficult to
is possible tor Caruel to propose the union of tliis species with P. Friderici-Auffxuli." But for those
largo suites of undoubtedly couspeciflo Siberian and Himalayan forms, the difficuUy i
" P. peliolarU
uover glabrous
bracts which
how with these charaeters alone i
eiiically.
» Hookei : Jntroiucto'-y Essai,
)1. ssiii, p. 379.
isible to propose that these two forms are to be looked c
separable
also Outlines of the Bistribulion of Arctic Pla<.