The Encyclopaedia Britannica; .. A dictionary of arts, sciences and general literature . rgans. Thus, the cones of Firsind the strobill of the Hop are composed of a series ofbracts arranged in a spiral manner, and covering fertileBowers; and the scales on the fruit of the Pine-apple areiif the same nature. In amenta or catkins the bracts arecalled squamce or scales. At the base of the general umbelin Umbelliferous plants, a whorl of bracts often exists,called a general involucre, and at the base of the smallerumbels or umbellules there is a similar leafy whorl calledinvolucel or partial involu
The Encyclopaedia Britannica; .. A dictionary of arts, sciences and general literature . rgans. Thus, the cones of Firsind the strobill of the Hop are composed of a series ofbracts arranged in a spiral manner, and covering fertileBowers; and the scales on the fruit of the Pine-apple areiif the same nature. In amenta or catkins the bracts arecalled squamce or scales. At the base of the general umbelin Umbelliferous plants, a whorl of bracts often exists,called a general involucre, and at the base of the smallerumbels or umbellules there is a similar leafy whorl calledinvolucel or partial involucre. In some instances, as inFools-parsley, there is no general involucre, but simply aninvolucel; while, in other cases, as in Fennel, neitherinvolucre nor involucel is developed. In Composite thename involucre is applied to the leaves, scales, or phyllaries,surrounding the head of flowers (tig. 146, i), as inDandelion, Daisy, Artichoke. This involucre is frequentlycomposed of several rows of leaflets, which are either of theeame or of different forms and lengths, and often lie over. Fig. 147. Fig. 146. pio. 148. -Head \capitulmn) of Marigold (Calendula), showing a congeries offlowers, enclosed by rows of bracts or phyllaries, •, at the base, which are col-lectively called an Involucre. Fio. 147.—Fruit of the Oak (Quet-evs pedunculala), ihowing a collection of bracts,a, forming the cup (cupula) of the acorn b. each other in an imbricated manner. When the bracts arearranged in two rows, and the outer row is perceptiblysmaller than the inner, the involucre is sometimes said tote caliculate, as in Senecio. The leaves of the involucreare spiny in Thistles and in Dipsacus, and hooked inBurdock. - Such whorled or verticillate bracts ma,y. either remain separate (polyphyllous), or may be united by cohesion(gamophjllous), as in many species of Bupleurum, and inLdvatera. In Composita: besides the general envelope calledthe involucre, there are frequently chaffy and setose bractsat
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