Arctostaphylos densiflora

Arctostaphylos densiflora, known by the common name Vine Hill manzanita, is a very rare species of manzanita. It is endemic to Sonoma County, California, where it is known from only one extant population of 20 to 30 individual plants. These last wild members of the species are on land near Sebastopol which is owned and protected by the California Native Plant Society. In addition, there are five to ten plants of this manzanita taxon growing on private property about a mile away.[2] The local habitat is mostly chaparral on sandy shale soils.

Arctostaphylos densiflora

Critically Imperiled  (NatureServe)[1]
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Ericales
Family: Ericaceae
Genus: Arctostaphylos
Species:
A. densiflora
Binomial name
Arctostaphylos densiflora

Pathogenic Risk

The entire wild population is infected with the root pathogen Phytopthera cinnamomi and subject to mortality, which could result in species extinction.[3]

Plants have been propagated through a collaborative effort by California Native Plant Society (CNPS) volunteers at the Vine Hill Preserve and the CNPS Nursery located at the Laguna de Santa Rosa Foundation near Santa Rosa, California. The purpose of the effort is to outplant to establish healthy genetically diverse plants at several locations other than the Vine Hill Preserve.[3]

Locations as of May 2023 with outplanting of disease free manzanitas include the Pitkin Marsh Preserve and Cunningham Marsh Preserve in Sonoma County. Others include Regional Parks Botanical Garden Tilden, the University of California Berkeley Botanical Garden, the San Francisco Botanical Garden, the University of California Santa Cruz Arboretum, San Francisco State University, the Mendocino Coast Botanical Gardens, and the northern most outplanting at the Humboldt Botanical Garden with six of the 20 genetic lineages.[3]

Description

Arctostaphylos densiflora is a small shrub growing in low, spreading clumps under one meter in height. Of the heath family, its shiny green leaves are oval to widely lance-shaped and less than three centimeters long.[4] It bears inflorescences of light to bright pink urn-shaped flowers. The fruit is a drupe about half a centimeter wide.

Ecological Relationships

The flowers of this species provide nectar for butterflies and native bees in the spring, berries provide food for birds in the late summer, and the low-growing habit of the plant make it a good home for California valley quail and wrentit nests. (Lowe 1999)[5]

Habitat

Roadside banks and neighboring areas in chaparral habitat with acid marine sand (York 1987).[6]

Species differentiation

A. densiflora likely appeared about 1.5 million years ago, although the Arctostaphylos genus itself arose in the Miocene era.[7]

See also

References
  1. "NatureServe Explorer 2.0".
  2. Center for Plant Conservation Archived 2009-08-19 at the Wayback Machine
  3. Moore, Mark (Summer 2023). "Vine Hill Manzanitas at the Humboldt Botanical Garden". The Botanical Guardian. Eureka, California: Humboldt Botanical Garden: 6.
  4. "National Collection of Imperiled Plants". 2009-08-19. Archived from the original on 2009-08-19. Retrieved 2023-05-27.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  5. Lowe, M. (1999). The Gardner's Guide to the Susal Creek Watershed: A Home Companion to Growing Native Plants. Aquatic Outreach Institute, Susal Creek Watershed Awareness Program.
  6. York, R. P. (1987). Elias, T. S. (ed.). California's most endangered plants. In: Conservation and management of rare and endangered plants. Sacramento, California: California Native Plant Society. pp. 109–120.
  7. C. Michael Hogan & Sarah Gordon. 2014. Arctostaphylos densiflora Archived May 21, 2014, at the Wayback Machine. ed. J. Lee. Encyclopedia of Earth. National Council for Science & Environment. Washington DC


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