UC specimens and range limits for Membranoptera platyphylla

• 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

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

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

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

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

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

Membranoptera Stackhouse 1809

Thalli erect or procumbent from small, conical holdfasts, alternately or subdichotomously divided into broad or linear blades. Blades with percurrent midrib more than 1 cell thick; portions lateral to midrib monostromatic and with or without diagonal parallel veins, occasionally with small proliferous blades from midrib and lateral veins. Internal cells with 3 orders of branching; terminal cells of third order not reaching margin; intercalary divisions within cell rows not occurring. Tetrasporangia tetrahedrally divided, in sori at blade apices, or scattered on either side of midrib and main lateral veins. Spermatangia in sori at blade apices, or scattered along midrib in upper halves of blades. Cystocarps borne on midrib, surrounded by hemispherical pericarp; carposporangia in chains.

Membranoptera dimorpha Gardn.

Gardner 1926: 211; Doty 1947b: 192; Scagel 1957: 218.

Thalli dark wine red, procumbent in groups, the blades linear-lanceolate, sparsely branching from margins; midribs conspicuous, traversing second- and third-order branches in upper portions; diagonal, lateral, and microscopic veins lying parallel throughout thalli; blades 8-15(25) cm tall, 5-8 mm wide, with smooth margins; midribs and laterals heavily proliferous, with small bladelets standing alternately at right angles to blades, these persisting on older plants otherwise eroded to midribs; bladelets oval on spermatangial and tetrasporangial plants, rounded to cordate on cystocarpic plants; tetrasporangia in sori on either side of midribs and larger lateral veins; spermatangia on main blades in sori similarly located; cystocarps basal to final dichotomies of lateral veins, or terminal on lateral veins in small bladelets, usually 1 or 2 per segment, with fimbriate ostioles.

Saxicolous or epiphytic: in drift at Amchitka I., Alaska, low intertidal from Queen Charlotte Is., Br. Columbia, to Carmel, Calif.; common in S. Ore. to Humboldt Bay, Calif., occasional to northward. Type locality: Neah Bay, Wash.

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