Zs. P. Komáromy szerk.: Studia Botanica Hungarica 14. 1980 (Budapest, 1980)
Rajczy, Miklós: A new measure for comparing the shape of moss leaves
STUDIA BOTANICA HUNGARICA (Antea: Fragmenta Botanica) XIV. 1980 p. 63-71 A new measure for comparing the shape of moss leaves By M. RAJCZY (Received November 10, 1979) Abstract: Two measures (leaf width/length and the new one called leaf part ratio, LPR) are proposed to characterize the shape of moss leaves. The method was tested on 33 moss leaves by means of cluster analysis. Using various handbooks and floras I often had problems with the descriptions of leaf shapes. The terms used (e. g. "wide ovate", "elongate-lingulate", etc.) are very subjective. Recently Hickey elaborated an exact system to determine dicotyledonous leaf shapes. The system consists of five main categories (oblong, elliptic, ovate, obovate and special shapes), and of sub-categories within these main ones, which depend of the leaf length/leaf width ratio (Hickey 1973). This system is quite a good one but somewhat complicated to use. Another problem is that there is no category in this system for the deeply acuminate leaves which are very frequently found in mosses. For example the "widely cordate-triangular" leaf of Eurhynchium striatum (Plate n. No. 29) is "wide ovate" only by these categories. Of course, there are other methods to characterize leaf shapes e. g. that of Koponen who used the width of leaves in three places (in the middle, in the upper and lower quarter of leaf) in his study (Koponen 1967). I propose a new measure to compare leaf shapes in mosses: 1dm where LPR is the new measure (Leaf Part Ratio); 1 is the length of the leaf; is the distance between the leaf base and the line where the width of leaf is maximum; ^dm2 * s * ne distance between the leaf base and the line where the width of leaf is half of the maximum width (see Fig. 1). The LPR is sensitive mainly to the shape of the upper half of the leaves and to the position to the maximum width. It is not sensitive to the relative width of the leaves at all, that is why it can be used together with the leaf width/length ratio. METHODS To test the new method I selected 33 drawings of leaves of various moss species, 30 from Dixon (1924) and 3 from Orbán (1974). The species used: Atrichum crispum (Jam.) Sull. et Lesq. ; Atrichum undulatum ( Hedw.) P. Beauv.; Atrichum angustatum (Brid.) B. S. G.; Pogonatum uraigerum (Hedw.) P. Beauv.; Pogonatum aloides (Hedw.) P. Beauv.; Tetraphis pellucida Hedw.; Rhabdo- weisia crenulata (Mitt.) Jameson; Oreoweisia bruntonii (Sm.) Mild.; Racomitrium aciculare (Hedw.)
