Page author: Hattie Palmer
Potamogeton fibrillosus
fibrous-stipuled pondweed
Specimens
Photos

Flowers: June - August

Origin: Native

Conservation Status: Review Group 1 in Washington (WANHP)

Description:
General:

Herbaceous wetland perennial; stems commonly with glands, to 0.5 mm diameter, cauline stems somewhat compressed; turions uncommon, when present may be lateral or terminal, up to 2.5 cm long and 2 mm broad.

Leaves:

Leaves submersed, generally spirally arranged, sessile; stipules inconspicuous, usually brown or uncommonly white, 0.2-2.2 cm, free from blade, fibrous and shredding at tip, veins persisting as fibers with age; blade light to olive green, uncommonly tinged red, linear, not curved, 1.3-8.2 cm long and 0.3-2.3 mm broad, base somewhat tapering, basal lobes absent and not clasping, margins entire and not wavy, apex not hoodlike, acute to apiculate, uncommonly bristle-tipped, lacunae rarely present, when present 0-2 rows on each side of midrib, veins usually 1-3.

Inflorescence:

Inflorescence a capitate to cylindric interrupted spike, up to 7 mm, unbranched, above water; peduncles emerging from axils of leaves nearest base, rarely from axils of distal leaves, curved backward, clavate, typically 0.3-1.1 cm.

Flowers:

Tepals 4, in 1 series; stamens usually 4, with distinct anthers dehiscing vertically, pollen spheric; pistils 1 or 4, usually lacking stipes but sometimes short-stipitate.

Fruits:

Drupes obovate to nearly orbicular, 1.4-1.7 mm long and 1.1-1.2 mm broad, light green; keeled beneath, 0.2 mm or less; beak erect, 0.2 mm high or less.

Accepted Name:
Potamogeton fibrillosus Fernald
Publication: Mem. Amer. Acad. Arts, n. s. 17: 51, plate 28, figs. a–c, plate 32, plate 28, fig. 5, plate 32. 1932 1932.

Synonyms & Misapplications:
Potamogeton foliosus Raf. ssp. fibrillosus (Fernald) R.R. Haynes & Hellq. [FNA22]
Potamogeton foliosus Raf. var. fibrillosus (Fernald) R.R. Haynes & Reveal [JPM]
Additional Resources:

PNW Herbaria: Specimen records of Potamogeton fibrillosus in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Potamogeton fibrillosus checklist entry.

E-Flora BC: Potamogeton fibrillosus atlas page.

CalPhotos: Potamogeton fibrillosus photos.

USDA Plants: Potamogeton fibrillosus information.

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