. The Canadian field-naturalist. 162 The Canadian Field-Naturalist Vol. 95 Occurrence of Incised Variations Plants which have the pinnae of both the fertile and sterile leaves deeply incised, giving the plants a ruffled appearance (Figure 5), have been given the name Asplenium plalyneuron var. incisum. Taylor et al. (1976), who reviewed the nomenclature and identifi- cation of the infraspecific taxa of the Ebony Spleen- wort, characterize var. incisum as having pinnae which are "doubly serrate to deeply incised; all or nearly all of the pinnae cut less than 4/ 5 of the way to the
. The Canadian field-naturalist. 162 The Canadian Field-Naturalist Vol. 95 Occurrence of Incised Variations Plants which have the pinnae of both the fertile and sterile leaves deeply incised, giving the plants a ruffled appearance (Figure 5), have been given the name Asplenium plalyneuron var. incisum. Taylor et al. (1976), who reviewed the nomenclature and identifi- cation of the infraspecific taxa of the Ebony Spleen- wort, characterize var. incisum as having pinnae which are "doubly serrate to deeply incised; all or nearly all of the pinnae cut less than 4/ 5 of the way to the ; The geographical and taxonomic significance of this variety relative to typical A. plalyneuron has been variously interpreted. Some authors, such as Shaver (1954), have considered it to be a coastal race of A. plalyneuron, while others, such as Correll (1956), have considered it to be only a shade-induced envi- ronmental form. Distribution maps (Shaver 1954; Steyermark 1963; Taylor and Demaree 1979) show it to be scattered throughout the range of A. plalyneuron. An Ebony Spleenwort population in Lyndon Township, Washtenaw County, Michigan, which contained plants conforming to var. incisum, was stu- died to determine whether this taxon has an environ- mental or genetic basis. Thirteen samples were taken from a 20 X 20 m area, each composed of the largest frond from every plant within a plot of m-. Voucher specimens from this site are Wagner 79419 (MICH). The samples were uniformly spaced and included plants both low and high on the hillside and in both sun and shade. The collected fronds were scored for six characters thought to be correlated with the incised condition: greater frond length and width, greater maximum pinna length and width, greater number of pinnae, and non-confluent sori. In addi- tion, pinnae from typical A. plalyneuron and from var. incisum were cleared and stained for comparison of their venation and soral characters. Of 204 plants sampled, 27 were
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