Eriogonum brevicaule Nutt. var. laxifolium (Torr. & A. Gray) Reveal. The geologic formation in this area of the canyon is the Precambrian-aged Big Cottonwood Formation containing tilting alternating layers of buff to red quartzite and shale ranging from black to purple to green, and it is said to be slightly metamorphosed. From about 900 million to 1 billion years ago, sand and clay were deposited by ocean tidal current and shoreline processes creating these layers. These are old rocks.As currently circumscribed, this is a taxon that only occurs in Utah (except for a small extension into the southeastern corner of Idaho) and mainly on the western side of the Wasatch in northern Utah. [Dr. Stanley] Welsh even treats it as an endemic, although, it has also in the past been somewhat of a dumping ground for various things within the brevicaule complex.Plants have more of a reddish tomentosum than other forms, flowering stems can be scapose as here, and the inflorescence can be either capitate (as here) or branched/divided. These plants are very different in appearance than var. brevicaule but it is difficult to describe that difference fully in words. The key taxonomic difference appears to be the stems which in var. brevicaule are glabrous whereas in var. laxifolium are not. What struck me was the geology and general beauty of the hidden location where these plants were growing, and their capitate heads (but that is not per se the taxonomic distinction). Var. brevicaule was also in flower in the general vicinity but not in the precise same location. Eriogonum umbellatum, well past flowering, was growing very near to this plant.October 9, 2008, lower Big Cottonwood Canyon, Salt Lake County, Utah, elev. about 5,750 ft., in a relatively secluded and remote location about 300 feet above the flume.
Eriogonum brevicaule Nutt. var. laxifolium (Torr. & A. Gray) Reveal.The geologic formation in this area of the canyon is the Precambrian-aged Big Cottonwood Formation containing tilting alternating layers of buff to red quartzite and shale ranging from black to purple to green, and it is said to be slightly metamorphosed. From about 900 million to 1 billion years ago, sand and clay were deposited by ocean tidal current and shoreline processes creating these layers (left).As currently circumscribed, this is a taxon that only occurs in Utah (except for a small extension into the southeastern corner of Idaho) and mainly on the western side of the Wasatch in northern Utah. Welsh even treats it as an endemic, although, it has also in the past been somewhat of a dumping ground for various things within the brevicaule complex.Plants have more of a reddish tomentosum than other forms, flowering stems can be scapose as here, and the inflorescence can be either capitate (as here) or branched/divided. These plants are very different in appearance than var. brevicaule but it is difficult to describe that difference in words. The key taxonomic difference appears to be the stems which in var. brevicaule are glabrous whereas in var. laxifolium are not. What struck me was the geology and general beauty of the hidden location where these plants were growing, and their mainly capitate heads (but that is not per se the taxonomic distinction). Var. brevicaule was also in flower in the general vicinity but not in the precise same location. Eriogonum umbellatum, well past flowering, was growing very near to this plant.October 9, 2008, lower Big Cottonwood Canyon, Salt Lake County, Utah, elev. about 5,750 ft., in a relatively secluded and remote location about 300 feet above the flume.
