Notes on the Polypodium vulgare Complex in South Dakota

Abstract

Throughout its range the Polypodium vulgare complex has been treated in various ways due to misapplied names and inadequately understood taxa. In South Dakota two members of the complex are present, P. hesperium Maxon and P. virginianum L., and both reach what may be their respective eastern and western distributional limits in central North America. The populations in western South Dakota have been referred to as a single species by some authors and as two species by others. I have determined that the western plants belong to a single species, P. hesperium, and that the eastern plants are P. virginianum. This represents the first documented report for this species in South Dakota. Over (1932) reported that specimens from western South Dakota belonged to a single species, P. virginianum L. Winter, Winter, and Van Bruggen (1959) segregated the plants of that area into two species, P. hesperium Maxon and P. vulgare L. (=P. virginianum), but did not discuss reasons for the separation. This treatment of the western plants was altered when Van Bruggen (1967), Brooks (1969), and Petrik (1969) referred the plants to P. vulgare L. Van Bruggen (1972) properly recognized the western South Dakota plants as P. hesperium. On specimens I examined from western South Dakota, paraphyses were not present among the sporangia, which according to Lang (1972) place the plants with P. hesperium. At present, P. hesperium has been collected in Custer (Stephens 35431 & Brooks), Pennington (Brooks 146 & Stephens), and Shannon Counties (Visher s. n., SDU), South Dakota. A specimen of P. virginianum from eastern South Dakota was found in the University of Kansas herbarium. The label on the sheet read: PLANTS OF SOUTH DAKOTA, Polypodium vulgare L., Minnihaha County: 3 miles south Garretson, Palisade Recreation Area, in crevices of Sioux quartzite outcrop, 10 July 1965, L. Harms 2688. Petrik (1969) first reported this specimen but did not distinguish it from the western South Dakota plants, referring them all to P. vulgare. I examined the Minnihaha County collection as well as several later collections made from the same site (Stephens 21317, Stephens 36487, and Brooks 1450) and determined that the plants are P. virginianum L. Frequent paraphyses were observed among the sporangia on all of the specimens examined, distinguishing the plants from P. hesperium in western South Dakota. This was substantiated by Dr. Rolla Tryon (pers. comm.), who kindly examined a specimen (Brooks 1450) from Minnihaha County, South Dakota. The Black Hills and Shannon County, South Dakota, are the only areas in the Great Plains where P. hesperium is known to occur. In these areas the plants normally grow in shaded crevices of granite rocks. Polypodium hesperium is especially frequent in areas of higher elevation in the Black Hills. The population