Noteworthy Collections: An Overlooked Specimen of Conyza ramosissima from Virginia

Published:

July – 2019

Author

Jill E. Spear

Additional Authors

W. John Hayden

Conyza ramosissima Cronquist (ASTERACEAE)

Page County: Rocky slope along road, 5 mi. NW of Luray, 20 June 1950, Bernard Mikula 5222 (FARM).

Significance: This is the first report of Conyza ramosissima (syn. Erigeron divaricatus Michaux) from Virginia. The specimen collected by Mikula establishing this record was encountered in the course of a study of herbarium material of C. canadensis (L.) Cronquist to distinguish its varieties [var. canadensis and var. pusilla (Nuttall) Cronquist] as they occur in Virginia; Mikula’s specimen had been initially identified as Erigeron canadensis L. Conyza ramosissima is best distinguished from other species in the genus by its profusely branched habit, generally lacking a well-defined main stem, its relatively low stature, usually ranging 1–3 dm tall, and strigose stem pubescence (Fernald 1950; Strother 2006). It also has distinctive white-margined phyllaries that lack the characteristic green tips found in C. canadensis var. canadensis or the red to purple tips typical of var. pusilla. In all respects, Mikula 5222 matches typical Conyza ramosissima. Examination of Conyza from FARM, GMUF, JMU, LFCC, LYN, ODU, URV, VPI, and WILLI failed to reveal any other specimen of Conyza ramosissima from Virginia, nor are specimens of this species held at the Shenandoah University herbarium (Woodward Bousquet, pers. com.). While geographic data for Mikula’s specimen are somewhat vague, the fact that Massanutten Mountain and the George Washington National Forest dominate the landscape northwest of Luray, Virginia, limits the likely locations for his roadside collection. Searches in the vicinity of all accessible pullouts on Rt. 675 on the mountain failed to reveal any trace of this plant on June 19–20, 2019. Distribution maps from the Biota of North America Program (BONAP) (Kartesz 2018) show C. ramosissima to occur widely in North America between, roughly, the 85th and 110th meridians; it appears to be most frequent in Kansas and Missouri. Notably, Conyza ramosissima was documented once in the late 19th C, presumably as a weed, from the Japanese Gardens, Fairmont Park, Philadelphia, Pennsylvania: Isaac Burk s.n., without collection date (PH). The Page County, Virginia, station reported here is at least 300 miles east of the nearest documented native occurrence on the BONAP map. The ruderal roadside habitat of this one known Virginia specimen is consistent with the weedy characteristic of the species and suggests that the status of waif is appropriate for this species in Virginia.

Keywords

noteworthy collections, Virginia, Asteraceae, herbarium