Introduction and recent range expansion in the moss Ptychomitrium serratum (Ptychomitriaceae) in the Southern and Eastern United StatesThis paper is one of a selection of papers published as part of the special Schofield Gedenkschrift.

Abstract

The moss Ptychomitrium serratum (C. Müll. Hal. ex Schimp.) Besch., is native to Mexico and parts of western Texas and southern New Mexico, and it is a rare adventive in the area from East Texas and Louisiana to Missouri, Tennessee, South Carolina, and northward to locations near the coast in New York State and Massachusetts. In the adventive part of this calcicole’s range, all collections are from the past 50 years. Concrete, mortar, and rarely asphalt shingle are its only known substrata in this region, which contrasts sharply with its common occurrence on limestone in the native portion of its range. These observations indicate recent, perhaps on-going, immigration into the eastern United States and dispersal from established populations in this region. This monoicous moss commonly produces spores, which are its primary means of spread. Given the low density occurrences in the adventive portion of the range of P. serratum, dispersal may be generally northeastward from Mexico – Texas – New Mexico, following northeastward storm tracks in the southern and eastern United States. The apparently recent spread of this moss does not show obvious reliance on any direct human activity.