common liverwort

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NNR - Unranked

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Common liverwort is a large, very common, widely distributed, thalloid liverwort. It is one of the largest liverworts. It is cosmopolitan in distribution, occurring on every continent except Antarctica. It is very common in Minnesota. It is found in permanently moist and intermittently wet areas in partial sun to medium shade. It grows on moist or wet soil in swamps, calcareous fens, wet meadows, cliffs, springs, disturbed areas, and recently burned areas. It often forms colonies of overlapping plants, sometimes creating extensive mats. The colonies are sometimes composed of all male or all female plants. It can be a pest if allowed to invade a greenhouse.

The vegetative body is a flat, lobed, ¾″ to 4″ long, ¼″ to 4″ wide plant body (thallus). The cells of a thallus are not differentiated into organs. It has no stem, leaves, vascular system, or true roots. The lobes are 1½″ to 2⅜″ long, ¼″ to ½″ wide, up to 1 ⁄16″ (1.5 mm) thick at the base, and thinner near the tip. The bases of adjacent lobes often merge together. The margins are wavy, untoothed, and green, not reddish or purplish. It often has a dark, midrib-like furrow that is incomplete and looks spotty. It is not a true midrib because the thallus has no vasular tissue. The upper surface is bright green, opaque, and hairless. There are no scales on the upper surface. It is densely patterned with faintly indented, diamond-shaped areas (areolae). Each areola has a single, tiny, white-rimmed pore in the center. The areolae are very small and barely visible to the naked eye. The pores require a 10x hand lens to see. The underside of the thallus is very different. It is covered with colorless scales and has numerous large bundles of root-like filaments (rhizoids). Long wiry rhizoids attach the plant to the soil. Short, peg-like rhizoids absorb water. The plants is not aromatic, even when crushed.

Liverworts reproduce both sexually and asexually. The asexual reproductive structure of common liverwort is a splash cup (gemma cup) that is produced on the upper surface of the thallus. Gemma cups are almost always present and are produced on both male and female plants. The cups are green, circular, and shallow. Each cup has a few egg-shaped, 1 ⁄32″ (1 mm) long gemma. The gemmae are dispersed when they are splashed out by raindrops. Each gemma can produce one or two plants if it lands on soil.

The male sexual reproductive structure (antheridiophore) is a short stalk topped with a flat disk that contains the male reproductive organ (antheridia). The stalk is ⅜″ to 13 ⁄16″ long, purplish, and hairless. The disk resembles a flattened umbrella. It is flat and has 6 or 8 rounded lobes. Each lobe has a warty, purplish or grayish band of spores that radiates out from the center. The margins of the disk are translucent.

The female reproductive structure (archegoniophore) is umbrella-shaped. It consists of 8 to 11 narrow, green lobes radiating from the top of naked, purplish, 1½″ to 2⅜″ long stalk. The lobes droop downwards, and the margins of the lobes are turned downwards. The underside of the lobe is lined with ovaries.

Prostrate: ¾″ to 4″ long

Marchantia is the only genus of complex thalloid liverworts that creates cup-like gemmae.

Snakeskin liverwort (Conocephalum conicum) areolae are much larger and conspicuous, clearly visible without magnification. They give the thallus a snakeskin-like appearance. It does not produce gemma cups. The raised area around each pore is clearly visible without magnification, though to see the pore itself requires a 20x hand lens. When crushed, it is strongly aromatic. The archegoniophore is rarely produced and is cone-shaped, not umbrella-shaped.

Water liverwort (Marchantia aquatica) is much less common. It has a prominent and uninterrupted dark, midrib-like furrow in the middle of each thallus.

Moist or intermittently wet. Swamps, calcareous fens, wet meadows, cliffs, springs, disturbed areas, recently burned areas, and greenhouses. Partial sun to medium shade.

July

Sources

4, 24, 29, 30.

Bryophyte surveys of selected old growth forest stands and other sites in northeastern Minnesota (1994-1996); Bowers, Frank D., Ph.D.: 1999.

Janssens, J.A. 2014. Noteworthy Mosses & Liverworts of Minnesota, Part II: Species Fact Sheets. Minnesota Department of Natural Resources 2014, 208 pp.

Native

Very common and widespread

It is likely that the species Marchantia polymorpha evolved from a hybrid between Marchantia alpestris and Marchantia aquatica. M. aquatica has a prominent and uninterrupted black longitudinal line in the middle of each thallus. M. alpestris lacks this line. M. polymorpha, the most common, is intermediate between the other two.

Some authorities consider M. alpestris and M. aquatica to be varieties of M. polymorpha, but this is not widely accepted. Some consider M. aquatica to be a synonym of M. polymorpha.

Common Liverwort

…it is located underneath the stairs leading up to my attic loft in La Crescent. This area is always shaded and usually moist.

Location: La Crescent, MN

Common Liverwort, it is located underneath the stairs leading up to my attic loft in La Crescent. This area is always shaded and usually moist.