MONTANA FIELD GUIDE™

GROWTH FORM: Leafy.

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.

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.

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

Dioicous - separate male and female liverwort plants.

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