indusium

Sori hemispheroid, in 2-3 series on each side along the costules, without indusium.

孢子囊圆形，沿中脉两侧各排成2-3行，无囊。

Indusium The flap of tissue, derived from the placenta, that encloses the developing sporangia in the sorus of a fern.

一种起源于胎座（为叶表皮译者注）状组织，覆在蕨类植物孢子囊中正在发育孢子囊上。