Rhabdoweisia crenulata New to North America

Abstract

Rhabdoweisia crenulata (Mitt.) Jameson, collected in McDowell County, North Carolina, is new to North America. On July 20, 1965, I collected Rhabdoweisia crenulata (Mitt.) Jameson in good fruiting condition from a wet ledge at about 3,300 feet on the south-facing slope of the gorge of Newberry Creek northwest of Old Fort, McDowell County, North Carolina. The station is about 50 feet above the creek in an area of constant seepage as indicated by a mat of Aulacomnium palustre just below the ledge. The plants grow in loose mats associated with Onchophorus rauii, Dicranodontium denudatum, Isopterygium borrerianum, Andreaea rothii, and Rhabdoweisia denticulata. The Newberry Creek collections agree with European specimens in Duke Herbarium, and a duplicate was verified by A. C. Crundwell. This is the first known American 1 The research was aided by Grant GB-2496 from the National Science Foundation to the Highlands Biological Station. I thank Dr. Lewis E. Anderson for help with determinations and in preparing the manuscript. 2 Department of Botany, Duke University, Durham, North Carolina 27706. This content downloaded from 40.77.167.80 on Mon, 13 Jun 2016 05:20:49 UTC All use subject to http://about.jstor.org/terms 1966] ZANDER: RHABDOWEISIA CRENULATA 357 TABLE 1. A comparison of the major differences between Rhabdoweisia crenulata and R. denticulata. R. crenulata R. denticulata Length of stems 0.5-2.5 cm 0.5-1.0 cm Shape of leaves Lingulate, 2-4 mm long, Linear-lanceolate, 2-3.5 mm apex obtuse to broadly long, apex acute acute Margin of leaves Dentate in upper oneSerrulate to nearly entire fourth to one-half near apex Upper leaf cells Quadrate to hexagonal, Rounded-quadrate to rec10-20k, thin-walled tangular, 8-15U, walls mostly moderately thickened Peristome teeth To 300 long, subulate To 200u long, linear-lanceolate from a broader base base station for Rhabdoweisia crenulata, which has a range, according to Lawton (1961), which includes the British Isles, Germany, Belgium, France, Sikkim, China, and Formosa. This moss, like many others in the southern Appalachians (Billings & Anderson 1966, Iwatsuki 1958, Sharp 1941), may be considered a relic of a flora common to Asia, North America, and Europe during the Tertiary. The only consistent difference between the American and European plants of Rhabdoweisia crenulata in Duke Herbarium is stem length. The American plants are shorter, between 0.5 and 1.0 cm long, and lack subapical innovations, which are usually present in European specimens. Otherwise, the Newberry Creek collection has the characters described and illustrated in Lawton's (1961) monograph of the genus Rhabdoweisia. Table 1 gives a comparison of the major characters used in distinguishing R. crenulata from the more frequent R. denticulata, the only other species of Rhabdoweisia which has been found in America north of Guatemala. Newberry Creek is a small cascading stream arising at Deep Gap at about 4,500 feet, just below the crest of the eastern escarpment of the Blue Ridge Mountains in North Carolina. The creek flows toward the southeast, and, after descending 2,900 feet in a distance of one and one-half miles, empties into Curtis Creek at 1,600 feet near the base of the escarpment. The slopes of the gorge cut by Newberry Creek are generally not so steep as those of more southerly escarpment gorges, notably the great gorges of the embayment area of the southern Appalachians (Billings & Anderson 1966) 65 miles to the southwest. The yearly precipitation is much less than that of more southerly gorges, averaging only 50 inches as judged by Weather Bureau data from surrounding towns. Occasional open glades in the gorge support a forest of hemlock and mixed hardwoods. My collections and those which I made during a subsequent visit to the gorge with L. E. Anderson on June 13, 1966, contained several This content downloaded from 40.77.167.80 on Mon, 13 Jun 2016 05:20:49 UTC All use subject to http://about.jstor.org/terms 358 THE BRYOLOGIST [Volume 69 mosses rare in the southern Appalachian Mountains; namely, Bryoxiphium norvegicum, Merceya ligulata, Herpetineuron toccoae, Heterocladium heteropteroides, Cirriphyllum piliferum, Homalia trichomanoides, and Diphyscium cumberlandianum. AMERICAN COLLECTIONS OF RHABDOWEISIA CRENULATA NORTH CAROLINA. MCDOWELL CO.: On a wet ledge at about 3,300 ft, S-facing slope of the gorge of Newberry Creek, about 8 mi NW of Old Fort, Zander 1723 (DUKE); the same, Anderson & Zander 19071 (DUKE).