I’ve posted previously on visiting the low sand dunes at Tonopah Junction in Mineral County, near Rhodes Marsh. Sarcobatus vermiculatus (Greasewood) and Suaeda nigra (Bush seepweed) dominate the vegetation here, largely stabilizing the dunes. I visited again this month (May 2022) and was greeted with a spectacular display of Carsonia sparsifolia (Fewleaf spiderflower or Naked spiderflower). Carsonia is a monotypic genus (just one species) in the Spiderflower family, Cleomaceae, although Carsonia was originally placed in the closely related genus Cleome.
Carsonia flowers have 4 green sepals, 4 yellow recurved petals, and 6 exserted stamens. Fruits are slender and generally borne on an elongated gynophore (a basal stalk that extends the ovary and fruit beyond the receptacle where sepals and petals are attached). Leaves are usually palmately compound, often trifoliolate (with 3 leaflets), with a short, orange-yellowish petiole-like stalk (a petiolule) at the base of each leaflet. The uppermost leaves are often simple, looking like a single leaflet.
Within its range, Carsonia most resembles several species of Cleomella and Peritoma that have similar yellow flowers and trifoliolate leaves. Cleomella fruits are short (up to 6 mm long) and may be nearly as wide; Carsonia fruits are longer (15–45 mm) and thin (1–3 mm). Peritoma has a dense, many-flowered inflorescence; Carsonia has a very open, relatively few-flowered inflorescence.
As you can tell from these photos, Carsonia inhabits sand dunes, as well as sandy areas on alkaline lake margins. Carsonia has been collected throughout the western Great Basin, from Owens Lake and Ash Meadows north to the Black Rock Desert and Winnemucca, and from Carson Valley east to Railroad Valley and Sand Spring Valley. This population at Tonopah Junction has been previously documented in herbarium collections, but not on iNaturalist.
Does Carsonia occur in the Bodie Hills? Probably not, but it has been seen around the northeast side of Mono Lake.
Also flowering here this time of year: Oenothera deltoides ssp. piperi (Birdcage Evening Primrose).
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