Magnoliopsida (Flowering Plants): Malvaceae
Hall’s Bush-mallow (Malacothamnus hallii)
Potential Occurrence: Not Expected to Occur
Status:
Federal: None
State: None
CNPS: 1B.2
Other: None
© 1994 Dean Taylor
caricologist@gmail.com
© 2005 Tom Cochrane
© 2005 David A. Tharp
waterspot@verizon.net
Species Description: Hall’s Bush-mallow grows to 3 m with spreading stout branches and
sessile, white, dense, shaggy hairs (Rosattii 2008). The leaves are wider than long, cordate and
shallowly 3 to 7 lobed (Rosattii 2008). The inflorescence is a panicle like with 3 to 7 flowers per
node and leaf like bracts (Rosattii 2008). The flower buds area rounded with calyx lobes awl
shaped to lanceolate and petals pale pink to purplish white. The fruit segments are 3 to 5 mm,
shallowly notched and brown (Rosattii 2008).
Nomenclature: Malacothamnus hallii (Eastw.) Kearney Malvaceae (Regents of the University
of California 2010)
Synonyms: Malacothamnus fasciculatus (Torrey & A. Gray) E. Greene, Malvastrum hallii Eastw.
(Regents of the University of California 2010)
Distribution: This species occurs throughout California in the North Coast Ranges, the Sierra
Nevada Foothills, the central High Sierra Nevada, the San Joaquin Valley and the San
Francisco Bay Area (Rosattii 2010). CNPS (2010) finds Mendocino County occurrence needs
verification.
Life History & Threats: Hall’s Bush-mallow is an evergreen shrub blooming from May to
October and is threatened by development and non-native plants (CNPS 2010).
Habitat & Habitat Associations:
Vegetation Types: Habitat for this species is chaparral dominated by mostly evergreen shrubs
with thick, leathery leaves and stiff branches (CNPS 2010).
Topography and Microclimates: open chaparral (Rosattii 2008)
Elevation: 10 to 760 m (CNPS 2010) (The Study Area ranges from 230 to 710 m)
Conceptual Basis for GIS Model Development: Potential habitat in the Study Area was
mapped as chaparral (i.e. Northern Mixed chaparral or scrub oak).
Potential Occurrence in the Galbreath Wildlands Preserve:
Habitat: Habitat preferred by the Hall’s Bush-mallow is limited to chaparral dominated by
evergreen shrubs. Although scattered chaparral species (i.e., chamise) have been found in
isolated locations on south-facing slopes in the Preserve, the GIS map generally provides an
accurate description of chaparral distribution as not occurring within the Galbreath Wildlands
Preserve.
Nearest Occurrence:
Documented Occurrences in the Galbreath Wildlands Preserve: A previous site visit of
the Galbreath Wildlands Preserve did not find this species (SSU Field Station and
Nature Preserves 2010)
Nearest Occurrence to the Galbreath Wildlands Preserve: North of the Bay Area, Hall’s
Bush Mallow is known only from Mendocino County (4 occurrences) north of the
Preserve and to the east in Lake County (1 occurrence). (Calflora 2010). The nearest
occurrence to the Preserve is approximately 13 miles northeast of the Preserve in the
Navarro River watershed (Calflora 2010).
Summary: We anticipate that this species is “Not Expected to Occur” in the Galbreath Wildlands
Preserve due to the lack of potential habitat (chaparral).
References
Calflora. 2010. Information on California plants for education, research and conservation.
<http://www.calflora.org/> Accessed 2010 Jul 2.
California Native Plant Society (CNPS). 2010. Inventory of Rare and Endangered Plants. Online
edition, v7-10b. <http://www.cnps.org/inventory> Accessed 2010 Jul 2.
Rosatti T. 2008. DRAFT Second Edition of the Jepson Manual: Vascular plants of California.
<http://ucjeps.berkeley.edu/tjm2/review/treatments/brassicaceae_all.html#10626>. Accessed
2010 Jul 2.
SSU Field Stations and Nature Preserves. 2010. Galbreath Wildlands Preserve Vascular Plant
List. Compiled by CNPS Milo Baker Chapter, Linden Schneider, and others.
<http://www.sonoma.edu/preserves/docs/galbreath_vascular_plants.pdf> Accessed 2010 Jun.
Regents of the University of California. 2010. The Jepson Online Interchange California
Floristics. <http://ucjeps.berkeley.edu/interchange/> Accessed 2010 Jul 19.
Species Account Description: Linden Schneider & Emily Harvey