Arctostaphylos crustacea explained

Arctostaphylos crustacea, commonly known as brittleleaf manzanita,^[1] is a species of manzanita found mostly in the fog belt of the Central Coast of California and the San Francisco Bay Area.

Description

Plants of this species are generally shrubs of up to in height,^[2] with smooth, reddish bark,^[3] and ovate leaves that are long.

This species, unlike many others manzanitas, has bifacial leaves, leaves which mostly only have stomata on their lower surface. ^[4] Fruits of this species are depressed-globose (shaped like a squashed sphere) drupes which contain multiple separate nutlets. The flowers are urn-shaped and grow on multi-branched panicles. Plants of this species, like some others in the genus Arctostaphylos, have a burl at their base from which they resprout from after the shrub is top-killed by fires.

Taxonomy

This species used to be part of the Arctostaphylos tomentosa complex, but was split in 2007. Below is a list of subspecies:

• Arctostaphylos crustacea subsp. crustacea — nominate subspecies; it has hairy twigs with long and short bristles with the lower side of its leaves mostly hairless. It's found in the Santa Cruz Mountains, the East Bay Hills, as well as parts of Monterey and San Luis Obispo counties.

• Arctostaphylos crustacea subsp. crinita — This subspecies has hairy twigs with long and short bristles, with the lower side of its leaves covered with dense hairs. It is found in the southern Santa Cruz Mountains and some isolated parts of the Central Coast.

• Arctostaphylos crustacea subsp. eastwoodiana — This subspecies has twigs that are hairy but without long bristles and leaves with glabrous undersides. It has a very limited range, found in western Santa Barbara County near Lompoc, mostly on substrate derived from siliceous rocks, twigs hairy but without long bristles.
• Arctostaphylos crustacea subsp. insulicola — This subspecies has twigs that are hairy but without long bristles and leaves with hairy undersides. It's found on Santa Rosa and Santa Cruz Islands, mostly on substrate derived from volcanic rocks.
• Arctostaphylos crustacea subsp. rosei — This subspecies has twigs that are hairy but without long bristles and leaves with glabrous undersides. Its range is very fragmented, only being found in small specific areas from San Francisco to Monterey County.

• Arctostaphylos crustacea subsp. subcordata — This subspecies' twigs are covered with glandular hairs. It's found in Santa Rosa and Santa Cruz Islands.

Notes and References

1. Book: Kauffmann. Michael . Parker . Tom . Vasey . Michael . 2015 . Field Guide to Manzanitas . Backcountry Press . 978-1-941624-02-9.
2. Book: Wells, Philip V. . 2000 . Manzanitas of California: Also of Mexico and the World . P.V. Wells . 0-933994-22-2.
3. Parker . V. Thomas . Vasey . Michael C. . Keeley . Jon E. . April–June 2007 . Taxonomic Revisions in the Genus Arctostaphylos (Ericaceae) . 41425696 . Madroño . 54 . 2 . 148–155 . 10.3120/0024-9637(2007)54[148:TRITGA]2.0.CO;2.
4. Encyclopedia: Arctostaphylos crustacea . Flora of North America . September 29, 2009 . Oxford University Press . October 20, 2024.