Fig 3. Non-mature and mature false indusia and supplying pinnule veinlets.

(A) When non-mature false indusia desiccate (by cutting off the respective pinnule margins), they do not open completely but remain in a semi-open position. No spores become shed (see also S1 Video). (B) View on the adaxial, marginal surface of a pinnule. The connection line between a false indusium, which is situated underneath the lamina, and the pinnule is indicated. The veinlets supplying the false indusium are clearly visible. (C) Details of some of the open and of some of the still closed false indusia after the desiccation experiment described in paragraph 3b). (D) Pinnules with open false indusia show signs of desiccation and degradation in the vicinity of the false indusia (indicated by the arrow).