‖ involucrum
(ɪnvəʊˈl(j)uːkrəm)
Pl. -a.
[L., = wrapper, covering, envelope; f. involvĕre to enwrap, envelop, involve.]
1. Outer covering, envelope; covering membrane; = involucre 1.
| a 1677 Hale Prim. Orig. Man. iv. ii. 299 By this means the Earth was not at all conspicuous, but involved in an involucrum of Water. 1822–34 Good's Study Med. (ed. 4) IV. 186 Fragments of a fetus, which..have sometimes been surrounded by an adscititious involucrum. 1843 J. G. Wilkinson Swedenborg's Anim. Kingd. I. i. 18 The tongue is principally composed of small muscles, of nervous involucra or membranes, and of fat. |
2. Bot. = involucre 2.
| 1753 Chambers Cycl. Supp. s.v., The Involucrum consists of a multitude of little leaves disposed in a radiated manner. 1776–96 Withering Brit. Plants (ed. 3) I. 11 When it surrounds the base of the Umbel, it is called the general Involucrum; but, when it surrounds the base of an Umbellule, or little Umbel, it is called the partial Involucrum, or Involucellum. 1859 Darwin Orig. Spec. v. (1872) 116 These differences have sometimes been attributed to the pressure of the involucra on the florets. |
3. Zool. A kind of sheath about the base of the thread-cells of acalephs.
| 1877 Huxley Anat. Inv. Anim. iii. 141 In this state it is invested by an involucrum, which surrounds its base. |