Mindblown: a blog about philosophy.

The outer wall of a pollen grain (the inner wall being the intine), the sculpturing and internal layering of the exine usually provide useful taxonomic characters.  

(In ferns) without a membrane covering the sorus. Without an indusium, in ferns.  

Coming off in large, thin-layered flakes.  

Curved away from the central part [unusual term, not recommended].  

Running through to the apex and beyond, as a mucro; (In ferns) veins from the midrib of a pinna or pinnule running towards the base of the sinus between the lobes of that pinna or pinnule, usually joined by lateral veins from other vein groups; With the stem remaining in the centre, the other parts…

Hollowed out.  

Without auricles.  

With a rough surface or with hard projecting points.  

Without an aril.