Tholurna dissimilis in Oregon

Abstract

Tholurna dissimilis has been found in the state of Oregon on Carpenter Mtn., 300 km south of the Mt. Rainier localities in Washington. Tholurna dissimilis Norm. (Caliciales, Sphaerophoraceae), once thought to be endemic to Scandinavia, is known from several localities in British Columbia and the state of Washington (Otto, 1972). Since its discovery on the Olympic Peninsula and on Mt. Rainier during the XI International Botanical Congress (Otto, 1970), I have been trying to locate Oregon populations. Until recently my searches, which included the vicinities of Mt. Hood and Mt. Jefferson, have failed to turn up populations of Tholurna. The first known locality for Tholurna in Oregon is in the H. J. Andrews Experimental Forest, 75 km east of Eugene in Linn County. This forest is located in the Western Cascades and is an intensive study site for the Coniferous Forest Biome of the International Biological Program. Tholurna was discovered growing on twigs of Abies lasiocarpa (Hook.) Nutt. about 3 m below and to the northeast of the rocky summit of Carpenter Mtn. (122°8'W, 44°17'N; 1630 m alt.). My collection (Pike 3083) is from the tree closest to the summit. This tree is about 2 m high and stunted; it has been heavily infested by Adelges piceae (Ratz.), the balsam woolly aphid. The thalli of Tholurna are poorly developed and are widely scattered along the needlebearing portion of the twigs (Fig. 1, 2). Within about 10 m from this tree additional, healthy individuals of Tsuga mertensiana (Bong.) Sarg., Taxus brevifolia Nutt., and Abies lasiocarpa were examined but no Tholurna was found on them. Species growing associated with the Tholurna included Alectoria frenionlii Tuck., A. sarmentosa (Ach.) Ach., Hypogymnia imshaugii Krog, Parmelia exasperatula Nyl., and Platismatia glauca (L.) W. Culb. & C. Culb. 1972] SHORT ARTICLES 579 FIGURES 1-2. Tholurna dissimilis on twigs of Abies lasiocarpa (Pike 3083). — 1. Habit, with needles partly cut away to expose the thalli. — 2. Closeup showing thallus, podetia, and ascocarps. — Photographs by William C. Denison. 580 THE BRYOLOGIST [Volume 75 The Carpenter Mtn. locality is 300 km south of the closest known locality (Mt. Rainier), and is now the southernmost locality recorded in North America. Carpenter Mtn. is in a region receiving approximately 250 cm of precipitation annually, occurring mainly between the end of September and mid-May; the summer months are extremely dry. The sparseness and stunted condition of the Tholurna thalli found on Carpenter Mtn. suggest that the conditions found here are near the limit for the growth of this species. Specimens are deposited at the following herbaria: osc, cow, and us. I acknowledge the help of R. G. Robbins of the Entomology Department, Oregon State University, for determining the nature of the insect damage to the Abies twigs. The work reported in this paper was supported by National Science Foundation grant GB20963 to the Coniferous Forest Biome, Ecosystem Analysis Studies, U.S./International Biological Program. This is contribution No. 53 from the Coniferous Forest Biome.