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conostomum moss, helmet-moss

Stems

brown.

Leaves

stiffly erect, keeled, 1–1.5 mm;

alar cells undifferentiated;

basal laminal cells rectangular;

distal cells 24–30 × 7–8 µm.

Seta

yellowish red to brown, 0.8–2.5 cm.

Capsule

ovoid, slightly asymmetric, 2–2.5 mm, neck short, swollen;

operculum obliquely rostrate, beak stout;

exostome teeth with border narrow, yellow, connate teeth forming perforated cone.

Spores

41–52 µm.

Perigonia

large, paraphyses subclavate.

Perichaetial

leaves subulate, base ovate, 2–2.5 mm.

Conostomum tetragonum

Phenology Capsules mature Jun–Aug.
Habitat Thin soil, cliff ledges, among boulders, waterlogged soil of late season snow melt
Elevation low to high elevations (0-2200 m) (low to high elevations (0-7200 ft))
Distribution
from FNA
AK; CO; ME; MT; NH; NY; OR; WA; AB; BC; NB; NL; NT; NU; QC; YT; c Asia; Greenland; Europe; n Asia
Discussion

Conostomum tetragonum is easily recognized by its glaucous, stiffly erect leaves in five rows and apically connate peristome teeth. Philonotis seriata (known only from Greenland in the flora area), shares a pentastichous leaf arrangement with C. tetragonum, but the laminal cells of P. seriata are prorulose at the proximal ends and the peristome teeth are free.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 28, p. 96.
Parent taxa Bartramiaceae > Conostomum
Synonyms Mnium tetragonum, C. boreale
Name authority (Hedwig) Lindberg: Öfvers. Kongl. Vetensk.-Akad. Förh. 20: 392. (1863)
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