annulus
annulus
1. In the fruit bodies of certain agarics, a remnant of the partial veil that adheres as a ring of tissue around the stipe.
2. A ring of cells around the sporangium of some ferns. The walls of these cells become progressively thicker around the circumference so inducing tension as they dehydrate, eventually causing the rupture of the sporangium. (The point of breaking is called the stomium.) The lid of the sporangium then curls back, releasing the tension induced by the annulus in a spring-like motion serving to aid spore dispersal.
1. In the fruit bodies of certain agarics, a remnant of the partial veil that adheres as a ring of tissue around the stipe.
2. A ring of cells around the sporangium of some ferns. The walls of these cells become progressively thicker around the circumference so inducing tension as they dehydrate, eventually causing the rupture of the sporangium. (The point of breaking is called the stomium.) The lid of the sporangium then curls back, releasing the tension induced by the annulus in a spring-like motion serving to aid spore dispersal.
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annulus
