Taxon Report
Malacothamnus arcuatus (Greene) Greene var. arcuatusarcuate bushmallow |
 © 2017 Keir Morse |
Taxon Summary
Malacothamnus arcuatus var. arcuatus, commonly known as arcuate bushmallow, is a perennial deciduous shrub in the Malvaceae that is found only in California. It occurs within Chaparral, and Cismontane woodland, growing at elevations from 15 to 355 meters. Malacothamnus arcuatus var. arcuatus is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.Classification
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Scientific Name: |
Malacothamnus arcuatus (Greene) Greene var. arcuatus |
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Common Name: |
arcuate bushmallow |
| Family: | Malvaceae |
| Element Code: | PDMAL0Q0E0 |
| USDA Plants Symbol: | |
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Synonyms/Other Names: |
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Ecology and Life History
| Lifeform: | perennial deciduous shrub |
| Blooming Period: Apr-Sep | Apr-Sep |
| Elevation: | 15-355 (50-1165) |
| General Habitats: | Chaparral, Cismontane woodland |
| Microhabitat: | |
| Microhabitat Details: |
Conservation Status
| CA Rare Plant Rank: | 1B.2 |
| Global Rank: | G2Q |
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State Rank: |
S2 |
| State List: | None |
| Fed List: | None |
| Other Status: | SB_CalBG/RSABG |
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CRPR Changes: |
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Occurrence Data from the CNDDB
| Total Occurrences: | 37 |
| Element Occurrence Ranks: | |
| Excellent (A) | 3 |
| Good (B) | 4 |
| Fair (C) | 5 |
| Poor (D) | 2 |
| None (X) | 2 |
| Unknown (U) | 21 |
| California Endemic: True | |
| California Counties and Islands: Name (Code) | |
| San Mateo (SMT), Santa Clara (SCL), Santa Cruz (SCR) | |
| Quads: Name (Quad Code) | |
| Big Basin (3712222), Cupertino (3712231), La Honda (3712233), Laurel (3712118), Loma Prieta (3712117), Los Gatos (3712128), Mindego Hill (3712232), Montara Mountain (3712254), Mt. Madonna (3712116), Palo Alto (3712242), San Francisco South (3712264), San Mateo (3712253), Santa Teresa Hills (3712127), Woodside (3712243) | |
Threat List Data from the CNDDB
| Threat List Total: | 8 | |
| EOs with Threat Listed: | Total EOs | % of EOs |
| 14 | 38 % | |
| Development | 6 | 16% |
| Road/trail construction/maint. | 5 | 13% |
| Non-native plant impacts | 3 | 8% |
| Other | 3 | 8% |
| Erosion/runoff | 2 | 5% |
| Improper burning regime | 2 | 5% |
| Insufficient population/stand size | 1 | 2% |
| Wood cutting or brush clearing | 1 | 2% |
Notes
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Threats: |
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Threatened by alteration of fire regimes. |
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Taxonomy: |
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A synonym of M. fasciculatus in The Jepson Manual. See Manual of the Botany of the Region of San Francisco Bay, p. 66 (1894) by E. Greene for original description, Leaflets of Botanical Observation and Criticism 1:208 (1906) for revised nomenclature, and Leaflets of Western Botany 6(6):132-133 (1951) for taxonomic treatment. |
Citation
California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 30 January 2025].