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UC specimens and range limits for Pterosiphonia dendroidea
  • 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

Pterosiphonia Falkenberg 1897

Thalli chiefly erect from prostrate branches; erect branches alternately distichous, with subordinate branches of 1 to several orders. Branches cylindrical to strongly compressed, with 4-20 pericentral cells, usually uncorticated. Ultimate branchlets determinate, typically without trichoblasts. Tetrasporangia 1 per segment in straight series, mostly in ultimate branchlets, tetrahedrally divided. Spermatangial stichidia clustered near apices of determinate branchlets or on spurlike branchlets from determinate branches, distichously arranged, with or without sterile apices, arising from entire trichoblast primordium. Cystocarps ovoid to globular, briefly pedicellate.

Pterosiphonia dendroidea (Mont.) Falk.

Polysiphonia dendroidea Montagne 1838: 353. Pterosiphonia dendroidea (Mont.) Falkenberg 1901: 268; Smith 1944: 366; Dawson 1963b: 426; Ardré 1967: 37. Pterosiphonia gracilis sensu Hollenberg & Abbott 1966: 115.

Thalli brownish-red to deep red, mostly 2-10 cm tall, with numerous erect branches arising from creeping branches at intervals of mostly 3 segments; prostrate branches attached by groups of unicellular rhizoids, these out off from pericentral cells of adjacent segments; erect axes percurrent, with branching of 2 or 3 orders; branches of all orders connate for 2-2.5 segments, arising at intervals of 2 segments; ultimate and subultimate branchlets mostly determinate; segments of main axes 200-500 µm broad, distinctly to strongly compressed, the segments mostly broader than long; tetrasporangia 60-70 µm diam.; spermatangial stichidia cylindroconical, incurved, 100-160 µm long, borne distichously in clusters of 1 per segment, on slender spur branchlets adaxial toward base of determinate branches, with sterile apices of 1 to several cells.

Common, mostly saxicolous, midtidal to lower intertidal and subtidal (10 m), northern Br. Columbia to I. Magdalena, Baja Calif, and Chile. Type locality: Peru.

This is a highly variable species. Variants include delicately branched forms mostly 2-3 cm tall, epiphytes, and an infrequent coarse form with prominent percurrent axes and bearing uniformly short laterals with short ultimate branchlets.

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

Classification: Algaebase


Type locality: Peru: Callao; Chile

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Citation for this page: Pterosiphonia dendroidea, in Kathy Ann Miller (ed.), 2018 California Seaweeds eFlora, [accessed on December 13, 2018]
Citation for the whole website: Kathy Ann Miller (ed.) 2018. California Seaweeds eFlora, [accessed on December 13, 2018].

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