UC specimens and range limits for Desmarestia viridis

• 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: Globally distributed, disjunct populations. On the west coast, from the Aleutian Islands through British Columbia, Canada, Washington and California. Absent from Oregon. In California, from Sonoma, Monterey and Los Angeles counties. This species is probably under-represented in herbaria due to sulfuric acid self-destruction.

Status: California specimens of this broadly distributed species have not been critically analyzed with molecular methods. Now forgotten southern California species that have been sunk into D. viridis (D. pacifica Setchell & Gardner and D. filamentosa Dawson) should be re-evaluated.

Habitat: Kelp forest or soft sand habitats on worm tubes

Life History: Alternation of heteromorphic phases, with a macroscopic sporophyte and monoecious microscopic gametophytes (Nakahara 1984; Kornmann 1962b).

Search Sequences in GenBank

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 viridis (Müll.) Lamour.

Fucus viridis Müller 1782:5. Desmarestia viridis (Müll.) Lamouroux 1813: 45; Smith 1944: 119; A. Chapman 1972: 1 (incl. synonymy applicable to Pacific coast). D. pacifica Setchell & Gardner 1924b:6. D. filamentosa Dawson 1944a:236.

Thalli 15-45(100) cm tall, with cylindrical stipe; extremely fragile; axis percurrent, subcylindrical, 0.75-1.5 mm wide at base, oppositely branched; primary branches lax, pinnately branched, occasionally bipinnate; branches clothed with short branchlets, very rarely found with hairs.

Occasional to rare from late spring into late summer, saxicolous, subtidal (to 45 m), Alaska to Baja Calif. and Gulf of Calif.; in Calif., at Mendocino Co., Monterey Peninsula, and Santa Catalina I. Type locality: N. Atlantic.

A close examination of the Monterey Peninsula specimens indicates that most given this name are probably D. kurilensis Yamada.

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

Notes: D. kurilensis is rare and virtually unavailable for study in its native range in the Kurile Islands (Yang et al. 2014). It has not been conclusively demonstrated that D. kurilensis has been confused with D. viridis in California.