Marchantia polymorpha

Liverworts are primitive, moss-like plants that form leaf-like mats on the soil surface. If they are present in container plants when they dry out, these mats repel water, causing pots to dry.

Plants reproduce by wind-dispersed spores and (more commonly) by gemmae produced in cup-like structures. Gemmae are splashed out of the cups by rain or irrigation. Liverworts prefer moist, cool conditions, and occur primarily in crops with frequent irrigation, such as propagation areas and herbaceous perennials.

Liverworts are very challenging to manage. Inspect plants before purchase and eradicate new infestations before they can spread. Liverworts have been suppressed by some preemergence herbicides, mulches, and nonselective contact herbicides.  Persistent infestations will require frequent hand weeding and changes in cultural practices to achieve acceptable suppression.