Variation among Non-Lobed Sassafras Leaves: EDWIN W. HUMPHREYS.. The Vitality of Pine Seed in Serotinous Cones: J. C. BLUMER THE TORREY BOTANICAL CLUB OFFICERS FOR 1910 President HENRY H. RUSBY, M.D. Vice-Presidents EDWARD S. BURGESS, PH.D. JOHN HENDLEY BARNHART, A. M., M.D. TORREYA is furnished to subscribers in the United States and Canada for one dollar per annum; single copies, fifteen cents. Το subscribers elsewhere, five shillings, or the equivalent thereof. Postal or express money orders and drafts or personal checks on New York City banks are accepted in payment, but the rules of the New York Clearing House compel the request that ten cents be added to the amount of any other local checks that may be sent. Subscriptions are received only for full volumes, beginning with the January issue. Reprints will be furnished at cost prices. Subscriptions and remittances should be sent to TREASURER, TORREY BOTANICAL CLUB, 41 North Queen St., Lancaster, Pa., or College of Pharmacy, 115 West 68th St., New York City. Matter for publication should be addressed to JEAN BROADHURST Teachers College, Columbia University Sassafras is for various reasons one of the most interesting of our native trees. One of the interesting features, and the one that has probably attracted the most attention to the tree, is its variously shaped leaves. That each of these leaf forms in turn shows considerable variation in its characters is apparently not so definitely known, and the limits of such variation are still less known. Yet a study of these differences is of much interest, particularly from the viewpoint of paleobotany; for most of the identifications of fossil plants are based on leaves only and naturally the limits of leaf variation are of more importance to the paleobotanist than they are to the botanist who has, in addition to the leaves, other characters on which to base his identifications. It was for the purpose of determining, in a measure, how greatly the non-lobed sassafras leaves varied among themselves that the present study, based on leaves collected at random in Bronx and Pelham Bay Parks, New York, and on the Palisades of New Jersey, was made. The most obvious variation is in the proportion of length to breadth. At one extreme is a leaf in which the length is only one and two fifths times the breadth, making an almost circular leaf; while at the other is a leaf whose length is three and one half times the breadth, producing a very long narrow leaf. dividing the leaves into groups based on the relation between breadth and length, the following curve was prepared (FIG. 1). It should be stated that all the curves given here are based on the same five hundred leaves. The figures along the base line * Illustrated with the aid of the Catherine McManes fund. By [No. 4, Vol. 10, of TORREYA, comprising pp. 77-100, was issued April 26, 1910.] indicate the ratio between breadth and length adopted for each group, while the height of the curve is determined by the number of individual leaves in that group. It appears, from the curve, that the normal or common type of leaf is that which is about twice as long as it is broad. The progression from very 1-14 1-1 1-1 1-2 1-24 1-2 1-2% 1-3 1-3 1-3% 1-3 1-4 FIGURE 1. broad leaves to the common form is very abrupt, while that toward the long narrow forms, though still abrupt, is somewhat gentler, tending to show that variants toward the long narrow types are more common, at least among the leaves measured, than are those toward the broader forms. The shape of a leaf depends chiefly upon the relationship existing between its length and breadth, and upon the position of the broadest part of the blade. Therefore the curve expressing this relationship is to a certain extent prophetic as to what the predominant shape will be. It indicates that the ovate, obovate, oval, and elliptical leaves are likely to be in the majority. Which of these four forms will, however, predominate depends upon the position of the widest part of the leaf. The accuracy of this forecast is shown by the curve (FIG. 2). It In regard to the form of the tip there is also much variation. As most of the leaves are oval, obtuse tips might be expected to prevail. Though the curve (FIG. 3) shows that this is true, yet a surprisingly large number of other forms are shown. Some of these, for instance the emarginate, may possibly be due to wounding, but that cause can hardly be advanced for all of the variants. On the condition of the base, sassafras leaves may be divided into two large classes. The first of these includes those leaves in which the blade begins at opposite points on the petiole; the second those in which the blade starts at points that are not opposite, one side beginning at a point either higher or lower than shows that the greater number of leaves are of the shapes mentioned. And, since the widest part is for the most part near the middle, the dominant shape is oval. 60,6% SHAPES OF SASSAFRAS LEAVES OBOVATE LANCEOLATE OVATE DELTOID |