Guide to Liverworts of Oregon: Haplomitrium hookeri (Smith) Nees
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1b plants leafy > 3b leaves not divided, not ciliate > 6a oil bodies 2+ or unknown > 7b no small dorsal lobe > 10a succubous > 11b isophyllous > 25b leaves bilobed or entire > 27b Leaves entire >
Synonym: None.
Special Status: ORBIC List 2.
Recognition: The plants look like a flacid, fleshy, loose leafed Bryum. Hard to find in the field.
Distribution: Among other bryophytes, usually tightly packed on peaty soil; in Oregon known for a long time only from Linton Meadows, Three Sisters Wilderness, Lane County. In 2007 found on sandy flats along Sutton Creek at the coast, Lane County. In 2010 Duncan Thomas found it along the Obsidian Loop in the Three Sisters Wilderness.
Comments: I have searched extensively but not relocated this species along the rivulet in Linton Meadows where Scott Sundberg found it in 1979(?). The original collection consisted of only two shoots pulled out of a mat of Lophozia opacifolia. It was not noticed in the field. One of those shoots was fertile. Sadly, only a slide mount of the capsule and spores have survived; the other part of the collection had been preserved in alcohol and disappeared in the course of being used as demonstration material in the classroom. Therefore, finding the plants at Sutton Beach caused me great elation. This locality is apparently significant for its occurrence at sea level as much as its georaphic range extension. In the treatment for the Bryophyte Flora of North America, Bartholomew-Began gives the elevational range as 900 m or higher (http://www.mobot.org/plantscience/BFNA/v3/HaplHaplomitriaceae.htm; accessed June 2007). As with the previous Oregon record, the plant was not recognized in the field but noticed only when a turf of mixed Phaeoceros carolinianus and Blasia pusilla was examined under a stereo microscope in the lab. The shoots of Haplomitrium hookeri occurred as individual strands tightly interwoven among the other bryophytes.
The Sutton Beach population has disappeared, along with the species with which it associated. This association's diversity and biomass decreased gradually over a span of three years until every liverwort associated with Haplomitrium vanished. By 2011 the bryophyte community had changed dramatically, with none of the rarer species persisting. See discussion under Fossombronia incurva.
Haplomitrium hookeri - Sutton Beach, Lane Co., Oregon; DHW m2414d.
Haplomitrium hookeri - Male shoot with orange antheridia. Sutton Beach, Lane Co., Oregon; DHW m2414d.
Haplomitrium hookeri - Spores and elaters. Sutton Beach, Lane Co., Oregon; DHW m2414d.
Haplomitrium hookeri - Male shoot with young antheridia. Three Sisters Wilderness, Lane Co., Oregon; D. Thomas.
Haplomitrium hookeri; Sutton Beach, Lane Co., Oregon; DHW m1274c.
Haplomitrium hookeri from Frye & Clark 1943, p. 172.