Common Name: Hooker's flapwort (Edwards 2003)
Scientific Name: Haplomitrium hookeri (Smith) Nees
Division: Marchantiophyta (incorrectly called Hepatophyta in U.S. government taxon databases (e.g., ITIS 2008); see Stotler and Crandall-Stotler 2008)
Class: Jungermanniopsida
Order: Calobryales
Family: Haplomitriaceae
Technical Description: "Dioicous, male plants usually in separate tufts, shorter than the female plants but mostly as scattered individuals between other bryophytes, pale green and mostly unbranched above the soil. Lower leaves distant, obliquely inserted, upper leaves gradually larger and close together, crowded at the apex of the stem, here sometimes almost transversely inserted, concave, of varying shape, oval-lingulate-circular, towards the apex obtusely pointed, margin slightly undulate. Cells with very thin walls, in the middle of the leaves about 33-40 µm, larger towards the base, towards the apex of the leaf smaller. Oil-bodies 20 per cell, small, about 2 µm. Calyptra 5 mm long, cylindrical. Spores spherical, green-brown, about 25 µm, densely and finely papillose." (Arnell 1981)
Distinctive Characters: The plants look like a flacid, fleshy, loose leafed
Bryum. The leaf shape is variable on a single shoot, increasing in size from base towards apex. The three rows of leaves with round leaf apices will distinguish this from any other liverwort. "Haplomitrium hookeri is easily distinguished from other hepatics within the flora by its branched rhizomatous habit with erect leafy shoots, descending, leafless stolons, and the absence of rhizoids. It is further distinguished by the production of a true calyptra in lieu of a perianth, and massive sporophyte in which the capsule wall is 1-stratose with each cell traversed by a single annular longitudinal band." (Bartholomew-
Began 2001) It is difficult to notice in the field because it usually grows entangled among other liverworts. This difficulty of field recognition is well established (Schuster 1969).
Similar species: There are no species which are really similar. The similarity to the moss genus Bryum is superficial. Schofield (2002) suggests living plants look something like miniature brussels sprouts.
Life History: Published studies of life history traits in this species are not known. The species is perennial and should be identifiable throughout the year. Sex organs and capsules are produced in early summer in the coastal population (pers. obs.). A capsule was found in late summer at the montane site. Establishment in favorable microhabitats is most likely by stochastic events, not amenable to statistical prediction.
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Range, Distribution, and Abundance: Widespread but irregularly distributed over temperate and boreal regions, in both northern and southern hemispheres. In western North American reaches its southern limit in Oregon.
In Oregon it was found in Linton Meadows in the Three Sisters Wilderness and at Sutton Beach, both in Lane County. The latter locality is unusual as the species is otherwise known from, "late-snow areas near or above tree line in mountains" (Schofield 2002; see also Bartholomew-Began 2001). Everywhere rare, usually sparse, except for an extensive population found in the Mt. Baker region of Washington State (Worley 1969).
ORNHIC listed in Lane County.
BLM: Suspected in Coos Bay, Eugene, and Salem Districts.
USFS: Documented in Siuslaw and Willamette National Forests.
Suspected in Columbia River Gorge National Scenic Area, Deschutes and
Mt. Hood National Forests.
Habitat Associations: Growing on soil in full sun, intermixed with other liverworts and hornworts. At the montane site it was growing in a polster of
Lophozia opacifolia. At the coast it was found as individual strands in a dense mat of Anthoceros punctatus, Phaeoceros carolinianus, and Blasia pusilla. Here it is most closely associated with the hornworts. In Washington it occurred around the edge of boulders in the Mt. Baker region (Worley 1969).
Threats: Threats in the montane areas are trail building and trampling by livestock. The coastal site is also subject to horse travel as well as hiker impacts.
Conservation Considerations: At known sites, consider building or relocating trails to reduce trampling by hikers and livestock.
Conservation Rankings and Status:
Global: G4; Oregon: S1
ORNHIC List 3
Washington: Not ranked
BLM/USFS Strategic Species in Oregon
Other pertinent information:
Surveys and Survey Protocol: Crawl around on hands and knees in suitable habitats.
Key to Identification of the Species: Christy and Wagner 1996.
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Preparer: David H. Wagner
Edited by: Rob Huff
Date Completed: October, 2008
Updated in June 2009 by Candace Fallon (Update added Attachment 1, Photos, to the Species Fact Sheet).
ATTACHMENTS:
(1) Photos
References:
Arnell, S. 1981. Illustrated Moss Flora of Fennoscandia. I. Hepaticae.
2nd. Edition. Swedish Natural Science Research Council.
Bartholomew-Began, S. 2001. Haplomitriaceae. Bryophyte Flora of North
America, Provisional Publication, Missouri Botanical Garden http://www.mobot.org/plantscience/BFNA/v3/HaplHaplomitriaceae.htm
Accessed: June 2008.
Christy, J.A. & D.H. Wagner. 1996. Guide for the identification of rare, threatened or sensitive bryophytes in the range of the northern spotted owl, western Washington, western Oregon and northwestern California.
USDI Bureau of Land Management, Oregon-Washington State Office,
Portland. 222 pp.
Edwards, S.R. 2003. English Names for British Bryophytes. Third Edition.
British Bryological Society Special Volume No. 5.
Oregon Natural Heritage Information Center. 2007. Rare, threatened and endangered species of Oregon. Oregon Natural Heritage Information
Center, Oregon State University. Portland. 100 pp. http://oregonstate.edu/ornhic/2007_t&e_book.pdf
Schofield, W. 2002. Field Guide to Liverwort Genera of Pacific North America.
University of Washington Press, Seattle, Washington, U.S.A.
Schuster, R.M. 1966. The Hepaticae and Anthocerotae of North America.
Volume 1. Columbia University Press, New York.
Worley, I.A. 1969. Haplomitrium hookeri from Western North America. The
Bryologist 72: 225–232.
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Attachment 1 – Photos
All photos by Dr. David Wagner, under contract with the Oregon/Washington Bureau of Land
Management.
Shoot with calyptras and capsule
Perichaetial shoot
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Shoot male
Antheridia dehiscing
5

Leaf
Oil-bodies
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Capsule close up
Spores and elaters
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