gemma

silmu puhekieltä A bud; an asexual reproductive structure, as found in liverworts and hydra, able to produce new individuals from a cluster of cells.
1969, Rudolf Mathias Schuster, The Hepaticae and Anthocerotae of North America East of the Hundredth Meridian, Volume 1, Columbia University Press, https://books.google.com.au/books?id=830MAQAAMAAJ&q=%22gemmae%22&dq=%22gemmae%22&hl=en&sa=X&redir_esc=y page 527,

I know of no other genera with such intramarginal formation of true gemmae.

Gemmae are frequently longer than wide or of irregular shape.

According to Degenkolbe, gemmae-bearing leaves are always different in form from normal leaves.

In Marchantia polymorpha, high temperature promotes germination of gemmae (Dacknowski, 1907), and heat absorbed by the gemmae accelerates their germination (Fitting, 1942).