Marchantia polymorpha

Marchantia polymorpha is a flat, ribbon-like liverwort that grows on damp soil, stream banks, burned ground, and the surface of nursery pots across every continent except Antarctica. The thallus — the flat green body that takes the place of stems and leaves — is divided down the middle by a fine dark line and lies pressed close to the substrate, spreading by branching at the tip. Its most distinctive feature is the gemma cup: small green discs scattered across the surface that hold lens-shaped buds called gemmae, which splash out when rain hits them and start new plants where they land. In a terrarium it does best in cool, shaded, very humid conditions on bare damp soil or wet wood, and is one of the few liverworts that can flush out the parasol-shaped reproductive structures — the umbrella-like archegoniophores and antheridiophores — that earned the species its 'umbrella liverwort' name.