Plant KingdomHard
Question
In Dryopteris, the opeing mechanism of sporangium is effectively operatedby
Options
A.stalk
B.stomium
C.annulus
D.peristome
Solution
when the capsule of the sporangium in Druopteris matures, about 4 lower median cells of the jacket stretch tangentially. the two median ones identify the place from where the capsule opens. This is called as stomium. Theother cells of the jacket develop a thickening. At maturity the indusium dries exposing the sorus. due to loss of water in the annulus, the upper walls contract and inner ones straighten, the annulus coils. This feature exerts perssure on the walls resulting in the breaking of the capsule, between the cells of the stomium threedy, relesing the spores.
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