Except the Berkeley and San Rafael plants these can be told from robustum only by aid of the microscope to see the tubercles and rosulæ. Though specimens vary considerably in appearance, the presence or absence of teeth, the size and intensity of the rings, a parallel can usually be found in a good series of robustum.
11. Doelli. Stems 1½ to 2½ feet high, erect, dark green, 10 to 20 angled, the ridges with two rows of tubercles or short crossbands, the former predominating; grooves with irregular rows of rosettes; sheaths entirely black or with a narrow ashy band which is broader the second year; the leaves plainly 4 angled through the grooving of the central ridge; teeth persistent or becoming broken in age, rigid, erect, dark brown or black, grooved in the center, with narrow white margins and usually deciduous filiform tips. Somewhat resembles a robust E. trachyodon, which it is quite near.
Type European. British Columbia, near Wharnock Station, A. J. Hill; Vancouver, Macoun (as ramosissimum); Blacktail Deer Creek, Yellowstone Park, Knowlton. The latter is quite peculiar in appearance and approaches robustum. None of the specimens exactly agree, but will come here better than elsewhere. The Ames Botanic Laboratory, North Easton, Mass.
THE SPECIES-CONCEPTION AMONG THE TERNATE BOTRYCHIUMS.
By Willard N. Clute.
Living as I do in the midst of a region rich in specimens of the ternate Botrychiums, I have taken more than ordinary interest in the discussion of the relative rank to which the various forms should be assigned. After considerable study of the subject which has consisted of a careful balancing of the degree of differentiation in each form, as well as an examination of much material both in the herbarium and in the field, I have come to certain conclusions which I purpose to set down here.
Before the separate forms are discussed it may be well to say a few words on the variations of Botrychium ternatum in general. It is a noticeable fact that all the so-called new species of this section of the genus, have been based primarily upon the cutting of the sterile part of the frond. This is all the more remarkable since there are probably no other genera in which species are founded on the minor outlines of a mere leaf. One has but to turn to nature in any clime to see that leaves are not invariably of the same shape. Note the wide variation in the moonseed, the hollyhock, the sassafras, and some of the buttercups among flowering plants, and if it be contended that the cases are not parallel, take as further illustration the blood-root, which, like the Botrychium, produces but one leaf a year, and note the cutting of its single leaf. If all these forms of Botrychium are species, why have not the forms of the bloodroot been segregated? Moreover, if we are to recognize these forms of Botrychium as species, why should we not also recognize as such the three hundred forms of Athyrium filix-foemina, or the hundred or more forms of Scolopendrium? It is unavailing to say that these latter are mere gardeners’ varieties, for we have it on the authority of Mr. Druery, who is familiar with them all, that a large number come true from spores.
Experiments with flowering plants have shown that the thickness of leaves and the amount of cutting of their edges, may be altered by different degrees of moisture, sunshine, etc., to which they are exposed, and we may infer as much for the ferns. This being so, it is not difficult to account for the slight variations in cutting exhibited in plants from widely separated points in the United States.
It is, of course, possible to follow the latest writer on the subject, and consider each extreme of variation a distinct species, but I do not agree with him in the opinion that the naming of varieties is a stupid practice, nor do I see that it necessarily follows that because a species was named Japonicum from Japanese specimens that we must infer that its centre of distribution is in Japan. As I understand it, to take a familiar example, B. ternatum stands for a plant possessing certain characters no matter where found. If we should find another Botrychium that differed from this in some specific way, it would be correct to call it another species; but if it showed minor differences, slightly thicker or thinner leaves, a longer or shorter stipe, a little deeper notching of the leaves, etc.—all characters that vary with the locality—then it would seem more properly referred as a variety of the first species.
As I have noted in this journal there are certain slight differences between the Japanese B. ternatum and our familiar species of Eastern America, but these are not enough, I now believe, to make them two separate species, since all the differences are found in the texture and cutting of the sterile part of the frond. Under such circumstances I would arrange our American forms as follows: