Taxon Report
Dodecahema leptoceras (Gray) Rev. & Hardhamslender-horned spineflower |
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Taxon Summary
Dodecahema leptoceras, commonly known as slender-horned spineflower, is a annual herb in the Polygonaceae that is found only in California. It occurs within Chaparral, Cismontane woodland, and Coastal scrub (alluvial fans), growing at elevations from 200 to 760 meters. Dodecahema leptoceras is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.Classification
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Scientific Name: |
Dodecahema leptoceras (Gray) Rev. & Hardham |
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Common Name: |
slender-horned spineflower |
| Family: | Polygonaceae |
| Element Code: | PDPGN0V010 |
| USDA Plants Symbol: | DOLE |
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Synonyms/Other Names: |
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Ecology and Life History
| Lifeform: | annual herb |
| Blooming Period: Apr-Jun | Apr-Jun |
| Elevation: | 200-760 (655-2495) |
| General Habitats: | Chaparral, Cismontane woodland, Coastal scrub |
| Microhabitat: | Sandy |
| Microhabitat Details: |
Conservation Status
| CA Rare Plant Rank: | 1B.1 |
| Global Rank: | G1 |
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State Rank: |
S1 |
| State List: | CE |
| Fed List: | FE |
| Other Status: | SB_CalBG/RSABG |
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CRPR Changes: |
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Occurrence Data from the CNDDB
| Total Occurrences: | 42 |
| Element Occurrence Ranks: | |
| Excellent (A) | 0 |
| Good (B) | 13 |
| Fair (C) | 3 |
| Poor (D) | 0 |
| None (X) | 15 |
| Unknown (U) | 11 |
| California Endemic: True | |
| California Counties and Islands: Name (Code) | |
| Los Angeles (LAX), Riverside (RIV), San Bernardino (SBD) | |
| Quads: Name (Quad Code) | |
| Agua Dulce (3411843), Alberhill (3311764), Azusa (3411728), Blackburn Canyon (3311667), Burbank (3411823), Desert Hot Springs (3311685), Devore (3411724), El Monte (3411811), Hemet (3311668)*, Lake Elsinore (3311763)*, Mint Canyon (3411844)*, Mt. Wilson (3411821)*, Newhall (3411845), Oat Mountain (3411835), Ontario (3411716), Pasadena (3411822), Pechanga (3311741), Redlands (3411712), San Bernardino North (3411723)*, San Bernardino South (3411713)*, San Fernando (3411834)*, Sunland (3411833), Vail Lake (3311648), Van Nuys (3411824), White Water (3311686), Yucaipa (3411711)* | |
Threat List Data from the CNDDB
| Threat List Total: | 13 | |
| EOs with Threat Listed: | Total EOs | % of EOs |
| 31 | 74 % | |
| Development | 20 | 47% |
| Altered flood/tidal/hydrologic regime | 10 | 23% |
| Non-native plant impacts | 10 | 23% |
| ORV activity | 10 | 23% |
| Vandalism/dumping/litter | 8 | 19% |
| Other | 6 | 14% |
| Mining | 4 | 9% |
| Dam/Inundation | 4 | 9% |
| Foot traffic/trampling | 3 | 7% |
| Recreational use (non-ORV) | 3 | 7% |
| Road/trail construction/maint. | 3 | 7% |
| Biocides | 1 | 2% |
| Erosion/runoff | 1 | 2% |
Notes
| Many historical occurrences lost to urbanization and stream channelization; currently threatened by alteration of fire regimes, development, sand and gravel mining, flood control, foot traffic, proposed reservoir construction, recreational activities, vehicles, and non-native plants. See Proceedings of the American Academy of Arts and Sciences 12:269 (1877) for original description, Great Basin Naturalist Memoirs 2:169-190 (1978) for taxonomic treatment, Phytologia 66(2):83-88 (1989) for revised nomenclature, and Madroño 44(3):305 (1997) for discussion of Vail Lake occurrence. |
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Threats: |
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Taxonomy: |
Citation
California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 19 November 2025].