Common Liverwort Weed (Marchantia polymorpha)
Common Names
- Common Liverwort
- Umbrella Liverwort
- Liverwort
Description
Common Liverwort is a thallose liverwort that forms dense, green, flattened mats on moist soil, greenhouse surfaces, and nursery containers. It thrives in high-humidity environments with poor air circulation and spreads aggressively in damp conditions.
Identification
- Growth Form: Flat, green, lobed thallus with a smooth or slightly rough texture.
- Reproductive Structures:
- Asexual: Gemmae cups (small, cup-like structures) containing tiny propagules that spread via water splash.
- Sexual: Male and female reproductive structures appear on separate plants. The female structures resemble tiny palm trees, while the male structures look like small disks on stalks.
- Habitat: Prefers moist, shaded environments such as nursery trays, potting media, greenhouse floors, and around irrigation lines.
Spread
- Gemmae Dispersal: The primary means of spread in nurseries, where water droplets dislodge gemmae from gemma cups, allowing them to colonise nearby surfaces.
- Spores: Wind-dispersed spores contribute to long-distance spread but are less significant in nursery settings.
- Vegetative Growth: Rapid expansion of the thallus allows it to overtake pot surfaces and growing media.
Similar Species
- Riccia spp. (Crystalworts) – Similar flattened growth but lacks distinct reproductive structures of Marchantia polymorpha.
- Mosses (Bryophyta) – More upright, with tiny leaves, and do not form gemmae cups.
Common Liverwort is a persistent problem in greenhouse and nursery environments, requiring an integrated management approach to prevent infestation and minimise its impact.