Latin name: Marchantia polymorpha

Phylum:  Hepatophyta Class: Marchantiopsida

Common name: Liverwort
liverwort in pots Habit:  Dense, fleshy mat that grows prostrate over the surface of container crops and/or greenhouse and nursery floors.
thallus Foliage:  The leaf-like structure that covers the surface of the ground or container are called thalli (thallus in singular form).  Liverworts are not vascular plants, but a more primitive life form similar to mosses.  They do not have true leaves like most organisms we consider plants.  
liverwort flower thumb Flower:  Liverworts do not have flowers (and thus do not produce seed), instead they archegoniophores and antheridiophores (female and male sex organs).  Liverwort are unisexual, with male and female sex organs forming on different plants. Antheridiophores look like an umbrella while the female achegoniophores have finger-like projections.  

Seed:  Liverworts reproduce sexually by spores, not seed.  Liverworts can also reproduce asexually by gemmae (see section on foliage above).
fr Roots:  Marchantia do not have roots, they have rhizoids which are root-like structures that lack xylem and phloem.
Related species: Lunularia cruciata, which is another liverwort similar in appearance to Marchantia.

Special considerations:  The term liverwort refers to a group of about 6,000 species.  Only one, Marchantia polymorpha, is a weed problem in nurseries.  Are we giving all liverworts a bad rap because of one species?  It seems so.

(Observation made by Sven Svenson, Oregon State University)
control Liverwort control: Liverwort cannot be controlled by herbicides alone. Cultural practices must be implemented that complement herbicides.

Postemergence Control:  Evaluate our postemergence liverwort control trials. In these trials, we used only products currently labeled, or those for which the manufacturer is pursuing a label.

Preemergence Control: Evaluate 2003 container herbicide trials at Oregon State University

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