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Greenthread
Thelesperma megapotamicum
NatureServe conservation status
Global (G-rank): G5
State (S-rank): S2
External links
Species range
Estimate from download of data from Utah Rare Plant Database on July 18, 2024.
Geocat 5 observations: Extent of Occurrence: 5,480.067 km2.
Historic observations over 40 years old were not used.
Desert shrub, ponderosa pine–manzanita, and riparian communities at ca 1150 to 2200 m in San Juan and Washington cos.; Wyo. to Nebr., s. to Ariz., Texas, and Mexico, South America. The disjunct Washington County records are from along the West Rim trail in Zion National Park below Lava Point at about 2200 meters elevation, growing in openings in the ponderosa pine forest (Welsh et al. 2015).
Threats or limiting factors
The main threats are from habitat degradation due to grazing, drought, and invasive plant species.
Threats compiled using observations and notes from Utah Rare Plant Database and Utah Geospatial Resource Center GIS Data downloaded in 2024. Severity of impacts are not well known so ranges are provided where appropriate. Over half of known occurrences are within grazing allotments. Drought and climate change is also a threat and likely impacting this species through out it's range (Wrobleski, 2023). In riparian areas invasive plants (tamarix, Alhagi, Russian knapweed) may be impacting this species (Welsh et al 2015).
(UNPS, accessed 2024): A taxon not included in previous versions of the UNPS Rare Plant list, but its apparent rarity in Utah warrants further research. Only 10 specimens at BRY have been collected of this taxon. It has been found in Washington and San Juan Counties in Utah. In Washington County, this taxon is restricted to the Lava Point area of Zion National Park. This taxon's primary range is in the Great Plains. Habitat Specificity scored as "0" since the habitat is variable and does not seem unusual according to A Utah Flora ("Desert shrub, ponderosa pine–manzanita, and riparian... communities") and FNA ("Disturbed places on sands or clays, oak/juniper woodlands, desert scrub, yellow-pine forests"). Threats to this taxon may be primarily from grazing-related impacts, but it scored as "unknown" due to uncertainty. Trends are scored as "unknown" due to uncertainty of the magnitude of the impacts of disturbance on extant populations and the lack of population-level surveys. These data rank this taxon to the "Medium" list.
