Protonema

Protonema of Funaria hygrometrica

Protonema cells of the deciduous moss Physcomitrella patens

The protonema is the pre-germ of the mosses : If a moss spore falls on the ground, it does not immediately grow into a new moss plant, but first forms the protonema. Only when this is large enough does it form buds from which the moss plant grows. While the cells of the protonema divide through apical tip growth by means of a single-edged apex cell, the bud formation marks the transition to growth by means of a three-edged apex cell.

The protonema has very different shapes in the individual moss groups. In the large group of Bryidae it consists of green, single-celled filaments. The peat moss consists of a small thallus . In the gypsy moss it is ribbon-shaped.

Individual evidence

1. ↑ Ralf Reski (1998): Development , genetics and molecular biology of mosses. Botanica Acta 111, 1-15.