Photo taken at northern population near Fremont Peak in San Benito County © 2015 Brett Hall.

Photo © 2015 Brett Hall.

Photo © 2015 Brett Hall.

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Common Names - Gabilan Mountains manzanita

Family - Ericaceae (Heath Family)

State Status - none

Federal Status - none

Habitat

Open granitic outcrops in chaparral or Coulter-pine/chaparral woodland; < 710 m.

Key Characteristics

Erect shrub or small tree, 1–5 m high, lacking basal burl, bark medium- to dark-red; twigs and lower inflorescence bracts sparsely short-nonglandular-hairy, with short or sessile glands among the hairs; leaves with a glaucous gray waxy layer covered with short white hairs, often becoming glabrous with age, similar on both leaf surfaces, ovate, overlapping, petiole 1–4 mm, blade 1.5–3.5 cm long, base auriculate, clasping, margin entire, flat; inflorescence paniculate, 1–4-branched, nascent inflorescence pendent, bracts fleshy, deltate, lower leaf-like; ovary gen pubescent, becoming glabrous with age; fruit spheric, 10–15 mm wide, glabrous (A. glauca has fruit sticky-glandular), stones fused (Parker et al. 2013).

Flowering Period

February to April

Reference Population

Gloria Valley (San Benito/Monterey counties).

Global Distribution

Known only from two disjunct occurrences in the northern Inner South Coast Ranges in the northern and central Gabilan Range on the border between Monterey and San Benito counties (CNPS 2010).

Conservation

In the early 1990s, two botanists working independently encountered an unfamiliar, auriculate-leaved manzanita in the Gabilan Mountains. It emerged that it was a species new to science, which was described in 2004 from a type specimen collected near Fremont Peak (Parker and Vasey). The species appears to be of diploid hybrid origin as it shares the auriculate-leaf character of other, maritime members of the A. andersonii complex while the inflorescence bracts, large, globose fruits, and fused nutlets indicate relatedness to A. glauca (Parker and Vasey 2004). Parker and Vasey (2004) hypothesize that the muted maritime influence combined with the more interior influence in the Gabilan Range creates an intermediate climatic situation where a hybrid combining adaptation to these two regimes might succeed. Among the auriculate-leaved manzanitas, A. gabilanensis more closely resembles A. glutinosa (Lockheed Chalks), A. auriculata (Mt. Diablo), and A. luciana (San Luis Obispo County), rather than the less distant A. pajaroensis (northern Gabilan Range, Pajaro Hills) and A. hooveri (northern Santa Lucia Mountains) (Parker and Vasey 2004).

The northern occurrence is located in chaparral-pine woodland on a ridge near Fremont Peak and is quite extensive, though scattered as isolated individuals. As of 2005, The Nature Conservancy was working on an easement for this site (CNDDB 2015). The southern occurrence occurs in chamise chaparral near Gloria Valley and the Pinnacles National Monument and supports fewer than 30 individuals (Parker and Vasey 2004). Fieldwork is needed to determine whether there are additional populations in this area (CNDDB 2015).

References

California Natural Diversity Database (CNDDB). 2015. California Department of Fish and Wildlife RareFind 5. http://www.dfg.ca.gov/biogeodata/cnddb/mapsanddata.asp [accessed 14 February 2015].

CNPS, Rare Plant Program. 2010. Arctostaphylos gabilanensis, in Inventory of Rare and Endangered Plants (online edition, v8-02). California Native Plant Society, Sacramento, CA. http://www.rareplants.cnps.org/detail/2098.html [accessed 14 February 2015].

Parker, V. T. and M. C. Vasey. 2004. Arctostaphylos gabilanensis (Ericaceae), a newly described auriculate-leaved manzanita from the Gabilan Mountains, California. Madroño 51(3):322-325.

Parker, V. T. et al. 2013. Arctostaphylos, in Jepson Flora Project (eds.). Jepson eFlora. http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=80888 [accessed 14 February 2015].

Reviewer

Reviewed by Dr. Michael C. Vasey, March 2015.

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