Bract

Bract is a term applied to any leaf from the axil of which a flower or a floral axis is produced, instead of an ordinary leaf-bud or branch. In some cases the bracts present no marked differences from other leaves (e.g. Belladonna), and such flowers are then often termed axillary, meaning in the axils of unmodified leaves. In the great majority of cases, however, the familiar antithesis between vegetation and reproduction is strongly marked, the size and vegetative development of the leaf being greatly checked; thus the bract is usually small and entire, even though the vegetative leaves may be large and divided. They often exhibit an interesting gradation between leaves and petals, for the coloration of the flowers, which is so often evident for some distance down the flowering axis, may extend more or less completely to the bract; and this may go so far as to completely replace floral magnificence altogether, as in the Poinsettia and Bougainvillea (q.v.) of our greenhouses. The subordination of vegetative life may go so far as to suppress the parenchyma altogether at a very early age, leaving only a dead membranous structure, brown and wizened in the bract or spathe of the daffodil, or glossy and bright coloured in the immortelle and other so-called everlasting flowers. Finally, in Cruciferae the bracts have disappeared in the great majority of species; yet in exceptional cases (particularly in double or otherwise highly vegetative specimens), their entire or partial reappearance shows that the apparent anomaly of their absence in this family is only the extreme case of a physiological contrast which is perfectly normal. It will be noticed that the term is applied (1) to bracts proper, each subtending a single flower; (2) as in Composite, to the crowded leaves of the axis below the similarly crowded inflorescence (in which, however, true bracts subtending the florets also often occur—e.g. Zinnia, &c., also in Dipsacaceæ); (3) to the leaf subtending an entire inflorescence, which may be either free-growing, with minor bractlets (palm), or compressed, as in the spadix of Araceæ. Such a bract is termed a spathe.