Singhurst, J.R. and W.C. Holmes. 2012. Geranium pusiffum (Geraniaceae): New to Texas. Phytoneuron 2012-82: 1-3. Published 12 September 2012. ISSN 2153 733X GERANIUM PUSILLUM (GERANIACEAE): NEW TO TEXAS JASON R. SINGHURST Wildlife Diversity Program Texas Parks and Wildlife Department 4200 Smith School Road Austin, Texas 78704 jason. singhurst@tpwd state.tx.us WALTER C. HOLMES Department of Biology Baylor University Waco, Texas 76798-7388 walter_holmes@baylor.edu ABSTRACT Geranium pusillum, a native of Eurasia, is reported as adventive in the state of Texas. It is documented from Denton County, in the north central part of the state. KEY WORDS: Geranium, Geraniaceae, Texas, USA Geranium is a genus of about 350 species of worldwide distribution, with 137 species occurring in the New World. Aedo (2012) reports that 30 species occur in the USA, 16 introduced. The genus is poorly represented in Texas. Correll and Johnston (1970) treated six species but one of these, G. Jentum Wooton and Standley, has been determined to be based upon a misdetermination (Aedo 2012, p. 69). Turner et al. (2003) mapped five species as occurring in the state: G. carolinianum L., G. texanum (Trelease) A. Heller, G. caespitosum E. James, G. seemannii Peyritsch, and G. dissectum L. (which is cited as introduced). In his study of the genus in the New World, Aedo includes these same five species as occurring in Texas but treats G. seemannii as G. seemannii subsp. seemannii, conspecific with G. seemannii subsp. repens (H.E. Moore) Aedo of southern Mexico and Central America. A sixth species is added here to the Texas flora, with documentation of its occurrence. Geranium pusillum L. Texas. Denton Co:. 1.1 mi W of jct of Boss Range Rd. and Co. Rd. 407 on Co. Rd. 404, then N 6.0 mi from jet of Starder Ln. and Co. Rd. 407 on Starder Ln., 8 May 2012, J. Singhurst 19308 (BAYLU). Figure 1. About 120 plants of Geranium pusillum were found in scattered bare spots among small patches of Aegilops cylindrica in clay-loam soils along a periodically maintained electrical transmission line right-of-way that bisects a high quality tallgrass prairie. Associated species included Andropogon gerardii, Sorghastrum nutans, Salvia azurea, Delphinium virens, Liatris mucronata, Tridens muticus, Asclepias asperula, Carex microdonta, Sporobolus sp., Hymenopappus scabiosaeus, Camassia scilloides, Desmanthus illinoensis, Penstemon cobaea, Pediomelum sp., Echinacea atrorubens, Callirhoe Thelesperma filifolium, Stenaria nigricans, and Dalea multiflora. Singhurst and Holmes: Geranium pusifumnew to Texas 2 as Texas Parks and Wildlife Department Geranium pusillum L. Denton Co.: 1.1 miles W of Jel, of Boss Range Rd, and Co Rd 407 ‘on Co Rd 404, then N 6 miles from Jet. of Starder Ln and Co Rd 407 on Starder Ln J. Singhurst 19308 ‘ustrbuted by Baylor Unversity Figure. 1. Geranium pusillum L. (Singhurst 19308, BAYLU). Photo by Darrell Vodopich. Singhurst and Holmes: Geranium pusifium new to Texas = 3 The following comments are largely based upon Aedo (2012), except as otherwise cited. Geranium pusillum is a native of Eurasia that has been introduced to Australia, North America, and South America (Argentina and Chile). In North America, the species is known from the northern two-thirds of the USA (Virginia—Tennessee west to California, north to southern Canada. It is an early introduction to the USA, being cited by Torrey (1826) in Pennsylvania. This persistence perhaps indicates that the species will become a permanent resident in the state. The distribution nearest to Texas is northwest Arkansas (Carroll and Madison counties) and northeast Oklahoma (Adair and Sequoyah counties). Geranium pusillum is an annual characterized by having only five anther bearing stamens (Aedo 2012). All other species of Geraniwn known in Texas have ten stamens. ACKNOWLEDGMENTS We would like to acknowledge Mrs. Anne Smith for access to the Smith Ranch and the opportunity to study the ecology and flora of her tall grass prairie. We also are grateful to Darrell Vodopich, Department of Biology, Baylor University, for taking and processing the photograph of the Geranium pusillum specimen. LITERATURE CITED Aedo, C. 2012. Revision of Geranium (Geraniaceae) in the New World. Syst. Bot. Monogr. 95: 1— Correll, D.S. and M.C. Johnston. 1970. Manual of the Vascular Plants of Texas. Texas Research Foundation, Renner. Torrey, J. 1826. A Compendium of the Flora of the Northern and Middle States. Vol. 1. Stacy B. Collins, New York. Turner, B.L., H. Nichols, G. Denny, and O. Doron. 2003. Atlas of the Vascular Plants of Texas. Sida Bot. Misc. 24. Bot. Res. Inst. Texas, Fort Worth.