Single Record

PhotoRecords: Yes Richard Haswell: Rio Grande Co, CO junction of CR 10 and Hwy 112, 30 June 2024

Comments: In 2005 John Schenk, Mentzelia expert, vouchered Mentzelia longiloba from 3.5 miles northeast of Del Norte, at the junction of Hwy 112 and CR 10. He describes the species as "common along roadside." His is the only record of Mentzelia longiloba for the Watershed. Ackerfield (2022) does not include M. longiloba in her flora of Colorado, and BONAP shows only Monetzuma Co. In June of 2024, there were Mentzelia plants still growing at Schenk's location. They ranged from 21" to 24" high, their petals were light yellow, the intersinus distance between leaf lobes were more than 7 mm in the smallest leaves, and their seed coat cell was was sinuous. All these characteristics could fit M. multiflora as well as M. longiloba (see the 2024 photorecord linked above). In the USA, the distribution of M. longiloba is centered in Arizona, with many occurrences also in Nevada, Utah, southern New Mexico, and along the Rio Grande drainage of Texas to the Big Bend country. FNA's discussion of M. multiflora (written by Schenk) notes that that species does not occur in Arizona, Utah, or Nevada, and that records of it in those state are usually misidentifications of M. longiloba. BONAP wildly disagrees, illustrating the difficult taxonomic relationship between M. longiloba and M. multiflora.