Cupule

...They grow on the vegetative organs of the mother plant, develop into specific shapes that are dissimilar to those of the mother plant, then naturally fall off and germinate to form new individuals. In Marchantia polymorpha, multicellular, drum-shaped gemmae grow one after another from the epidermal cells at the base of the cupules that exist on the surface of the thallus, and these leave the mother plant and are washed away by rainwater and dispersed widely, each of which germinates to form new individuals. Gemma are not limited to Marchantia polymorpha, but are widely seen in mosses, and come in a variety of shapes, including powdery, filamentous, discoid, and club-shaped....

*Some of the terminology that mentions "cupule" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…母体の栄養器官上に生じ，母体に似ていない特定の形に発達したのちに自然に脱落し，発芽して新個体を形成する。ゼニゴケでは葉状体の表面に存在する杯状の構造(杯状体cupule)の底部の表皮細胞から次々と多細胞で鼓形の無性芽を生じ，それらが母体から離れ，雨水に流されて広く散布し，それぞれが発芽して新個体となる。無性芽はゼニゴケに限らずコケ植物に広くみられ，粉状，糸状，円盤状，こん棒状など，その形態はさまざまである。…

※「cupule」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報