UC specimens and range limits for Desmarestia latifrons

• Blue markers: specimen records
• Yellow marker: type locality, if present
• Red markers: endpoints of range from literature

View map from the Consortium of Pacific Northwest Herbaria

Notes: From Washington to northern Baja California, Mexico, including San Miguel, Santa Rosa, and San Nicolas islands.

Status: Specimens from Hearst Beach, San Luis Obispo Co. (Yang et al. 2014) and Harris Beach, Oregon (Kawai & Sasaki 2000) have been analyzed with rbcL. This species is distinctive.

Habitat: Exposed environments, sometimes associated with sand

Life History: An alternation of heteromorphic generations, with large foliose sporophytes and minute filamentous dioecious gametophytes

Search Sequences in GenBank

Illustration from DeCew's Guide to the Seaweeds of British Columbia, Washington, Oregon, and Northern California

Desmarestia Lamouroux 1813

Sporangial thalli perennial, elongate, remarkable in the field owing to large amounts of acids produced when plants are collected, bleaching nearby plants and producing an acrid odor. Holdfast stout, disklike, producing single erect axis, this soon forming opposite or alternate branchlets according to species, rarely unbranched. Axes and branches slightly to markedly compressed; some species remaining finely branched throughout, others becoming foliose. In Calif., a seasonal occurrence of hairs at margins of branches. Thalli containing unangia rarely collected in Calif.

Despite large size of some species (to 3 m long), internal structural features and cell modifications not as elaborate as in order Laminariales. Center of thallus with several axial strands having thick walls and surrounded by thick cortex of colorless cells, interspersed by colorless rhizoids. Surface layer of cells containing many lenticular chloroplasts, without pyrenoids. Tufts of hairs in which the intercalary meristem is found are terminal on branches. In older thalli, some transverse and longitudinal walls frequently pitted; cytoplasmic threads traversing the pits probable.

Desmarestia latifrons Kütz.

Kützing 1859: 40; Smith 1944: 120.

Thalli to 2 m tall, arising from disk-shaped base, dark brown to black; axis linear, compressed to flattened, 1.5-3 mm wide; branching of axis profuse, the long branches frequently formed near base, the shorter ones above, mostly alternate, with intervals of 10-30 mm between successive branches; axis and major branches with inconspicuous percurrent midrib; filaments along axis and branches 2-4 mm long, not found after July in C. Calif.; bare branches coarse and stringy.

Locally frequent, saxicolous, low intertidal to subtidal (15 m), in areas of strong surf, Coos Bay, Ore., to Government Pt. (Santa Barbara Co.), Calif. Type locality: Fort Ross (Sonoma Co.), Calif.

Excerpt from Abbott, I. A., & Hollenberg, G. J. (1976). Marine algae of California. Stanford University Press, Stanford, California. xii [xiii] + 827 pp., 701 figs.