D defs.my
Entry 2 senses Webster, 1913

Involucrum

· In·vo·lu·crum · IPA /ˌɪnvəˈluːkɹəm/
01 n. See Involucre.
pl. Involucra, Involucrums ((#))
  1. 1.
    See Involucre.(Bot.) See: Involucre
  2. 2.
    A sheath which surrounds the base of the lasso cells in the Siphonophora.(Zool.)