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Taxon  Report  
Oxytheca watsonii  Torr. & A. Gray
Watson's oxytheca
Oxytheca watsonii is an annual herb that is native to California, and also found in Nevada.
California Rare Plant Rank: 2B.2 (rare, threatened, or endangered in CA; common elsewhere).
Siskiyou Del Norte Modoc Humboldt Shasta Lassen Trinity Plumas Tehama Butte Mendocino Glenn Sierra Yuba Lake Nevada Colusa Placer Sutter El Dorado Yolo Alpine Napa Sonoma Sacramento Mono Amador Solano Calaveras Tuolumne San Joaquin Marin Contra Costa Alameda Santa Cruz Mariposa Madera San Francisco San Mateo Merced Fresno Stanislaus Santa Clara Inyo San Benito Tulare Kings Monterey San Bernardino San Luis Obispo Kern Santa Barbara Ventura Los Angeles Riverside Orange San Diego Imperial
Observation Search
(24 records)
yellowone or more occurrences
within a 7.5-minute quadrangle

Bloom Period
Genus: Oxytheca
Family: Polygonaceae  
Category: angiosperm  
PLANTS group:Dicot
Jepson eFlora section: eudicot

Communities: Creosote Bush Scrub, Joshua Tree Woodland, wetland-riparian
Name Status:
Accepted by JEF + CNPS + PLANTS

Alternate Names:
JEFEriogonum cuspidatum
Information about  Oxytheca watsonii from other sources
Nursery availability from CNPLX
Commercial availability unknown.
Jepson eFlora


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[explorer.natureserve.org] Conservation status: Oxytheca watsonii is known from three occurrences in Inyo county, California. Kartesz (1988) reported that it was infrequent to rare in four Nevada counties, although numerous populations had been found throughout the deserts within its range. Recent information on Nevada populations is not available. In California, sites are threatened by grazing and recreational use; in Nevada, Monzingo (1980) indicated that a proposed missile system threatened this taxon. (contributed by Mary Ann Machi)

[eflora.org] Description: Plants erect to spreading, 0.5 to 2.5 0.4 to 4 dm. Stems glandular throughout. Leaf blades spatulate or obovate to oblanceolate, 0.7 to 4 by (0.1-) 0.5 to 1.2 cm, strigose adaxially, less so abaxially, sparsely glandular on both surfaces. Inflorescences open to densely branched, 0.5 to 2 dm; bracts 1 to 5 by 0.5 to 3 mm, 3 (-5) at first node and linear to ovate, otherwise distinct or basally connate and linear to triangular, ciliate and glandular; awns 1 to 3 mm. Peduncles deflexed, stout, 0.2 to 0.5 cm at proximal nodes, sometimes absent. Involucres 1.5 to 2 mm, typically glabrous, rarely with few scattered hairs abaxially; teeth 4; awns reddish, 2.5 to 3 mm. Flowers 2 to 4 (-7); perianth white to pink, 1 to 1.5 mm, strigose and sparsely glandular abaxially; tepals dimorphic, entire, those of outer whorl oval to ovate and strigose abaxially, those of inner elliptic to oval or ovate and glabrous or sometimes pubescent adaxially at base; filaments 1 to 1.5 mm, glabrous; anthers cream to red, oval, 0.2 mm. Achenes dark brown to maroon, 1 to 1.5 mm. 2n = 40. Flowering Jun to -Oct. Sandy flats and slopes, saltbush communities; 1200 to 2000 m; Calif., Nev. Oxytheca watsonii is an uncommon species known only from scattered locations. The name was misapplied in pre1980 California floras to Acanthoscyphus parishii var. goodmaniana. (contributed by Mary Ann Machi)

Suggested Citation
Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals. [web application]. 2023. Berkeley, California: The Calflora Database [a non-profit organization]. Available: https://www.calflora.org/   (Accessed: 12/11/2023).