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A Liverwort - Porella navicularis

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Native Species

Global Rank: G5
State Rank: SNR

Agency Status


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General Description

PLANTS: Glossy, yellowish-green to brown plants that form dense, coarse mats. Shoots are 1-2 times pinnate and up to 12 cm long and 1.5 to 3 mm wide. Male plants have branches that are short and lateral, 1.5-2.5 mm long. Female plants have branches that are very short, lateral, and with a few smaller leaves at base. Perianth is broadly obovoid, 3-5 mm long, 2.2-4.0 mm wide. When mature the perianth tip is dorsiventrally compressed and bent toward the ventral side and the mouth is wide, deeply 2-lipped, and toothless.

UPPER-LEAVES: Dorsal leaves are flexed downward, and have entire margins. Lobules (ventral upper-leaves) are oval to ovate, two-fifths to one-half the width of the dorsal leaf. The margins area entire and recurved, and when dry the apex is commonly recurved.

UNDER-LEAVES: Imbricate, oblong-quadrate in shape, and with a fairly long decurrent leaf. The apex is rounded and sometimes recurved. Margins are entire at the under-leaf’s base. Trigones (triangular-shaped corner thickenings of the cells walls) are large and bulging, such that they bulge inwards on the cells.

Sources: Conrad and Redfearn 1979; Hong 1983; Piippo and Norris 1996.

Diagnostic Characteristics
Porella navicularis
* Size: Plants are glossy with shoots 1.5-3 mm wide.
* Trigones present - cell corners have the walls bulging inward.
* Lobules are neatly and noticeably revolute; nearly as wide as the under-leaves, and with an axis that diverges from the stem.
* Under-leaves are entire.
* Plants do not turn violet with iodine potassium-iodide (IKI).
* Plants are strongly aromatic, but not acrid.

Porella cordaeana
* Size: Shoots are 3-4 mm wide.
* Lobules are about half the width of the under-leaves.
* Under-leaves do not overlap, leaving stretches of the stem visible.
* Decurrent portion of under-leaves are ruffled with a few teeth along the bases.
* Plants turn violet with IKI.

Porella platyphylla
* Under-leaves overlap.
* The lobule margins are slightly revolute.
* Decurrent portion of under-leaves have smooth, slightly revolute margins.
* Plants turn violet with IKI.

Porella roellii
* Cells walls of the leaves without their corners bulging into the cell lumens.
* Under-leaves about twice as wide as the lobules.
* Lobules are oriented parallel to the main stem, and are much narrower than the under-leaves.
* Plants do not turn violet with IKI.
* Plants taste peppery when fresh (David. H. Wagner personal communication).

The Type specimen (from which the species was first described) was collected in the USA.
“West Coast hb Hooker”

Sources: Piippo and Norris 1996; Paton 1999.

Range Comments
Endemic to western North America: Alaska, British Columbia, California, Idaho, Montana, Oregon, Washington, and Wyoming (Hong 1987).

On trees, logs, and rocks within moist, shaded sites (Hong 1976).

Reproductive Characteristics
Dioicous - separate male and female liverwort plants.

Threats or Limiting Factors
Threats to Porella navicularis populations include loss of shade trees by forest fires and logging that degrades the habitat.

  • Literature Cited AboveLegend:   View Online Publication
    • Conrad, H.S. and P.L. Redfern. 1979. How to know the mosses and liverworts. Wm. C. Brown Co., Dubuque, Iowa. 302 pp.
    • Hong, W.S. 1976. Annotated checklist of the hepatics of Idaho. The Bryologist 79:422-436.
    • Hong, W.S. 1983. The genus Porella in North America west of the Hundredth Meridian. The Bryologist 86:143 -155.
    • Hong, W.S. 1987. Distribution of western North American Hepaticae: Endemic taxa and taxa with a North Pacific arc distribution. Bryologist 90:344-361.
    • Paton, J.A. 1999. The Liverwort Flora of the Bristish Isles. Essex, England: Harley Books. 626 p.
    • Piippo, S. and D.H. Norris. 1996. A revision of Californian Porella. Ann. Bot Fennici 33:137-152.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Christy, J.A. and J. Harpel. 1995. Bryophytes of the Columbia River Basin south of the Canadian border. Report to the Interior Columbia Basin Ecosystem Management Project. Oregon Natural Heritage Program. 298 p.
    • Christy, J.A. and J. Harpel. 1997. Rare bryophytes of the Interior Columbia River Basin and northern Great Basin, U. S. A. Journal of the Hattori Botanical Laboratory 82: 61-75.
    • Elliot, J. C. 1993. Second checklist of Montana mosses. Unpublished report. U.S. Forest Service, Region 1. Missoula, MT. 45 pp.
    • Holzinger, J. M. 1895. Report on a collection of plants made by J. H. Sandberg and assistants in northern Idaho, in the year 1892. Contributions to the National Herbarium 3: 205-287.
    • Hong, W. S. 1975. Leafy hepaticae of Montana and phytogeographic relationships to neighboring states and provinces. The Bryologist 78: 304-327.
    • Hong, W. S. 2002. 'A Key to the Hepaticae of Montana'. Northwest Science : Official Publication of the Northwest Scientific Association. 76: 271-285.
    • Moseley, R.K. and A. Pitner. 1996. Rare bryophytes and lichens in Idaho: Status of our knowledge. Boise, ID: Conservation Data Center, Idaho Department of Fish and Game. 50 p.
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Citation for data on this website:
A Liverwort — Porella navicularis.  Montana Field Guide.  .  Retrieved on , from