Sentence:  The capsule in both families is spherical, with a bistratose wall; the outer cell layer usually bears nodular thickenings...; the inner layer (of nearly equally large cells) lacks the regular semiannular or <WSD>annular</WSD> thickenings of most other leafy liverworts... 
Meaning of the word marked with <WSD> tags:  Pertaining to, or having the form of, a ring; ring-shaped; in the shape of an annulus.