Fig. 126.—'Rose plantain,' Plantago media var., spike contracted; bracts leafy.
Phyllody of the bracts.—As bracts are very generally imperfect organs, so their replacement by perfect leaves is not attributable to arrest of development or retrograde metamorphosis, but the reverse. The bracts of some species of Plantago[246] are very subject to this change. Thus, in the rose plantain of gardens, P. media (fig. 126), the bracts are leafy and the axis depressed or not elongated, so that it is surmounted by a rosette of small leafy organs. A similar condition of the bracts, unattended with arrest of growth in the axis, is common in P. major (fig. 127) and in P. lanceolata ([see p. 108]). It also occurs in the bracts of Corydalis solida, Amorpha fruticosa, Ajuga reptans, Parthenium inodorum, Centaurea Jacea, in the involucral bracts of the dandelion, the daisy, and many other composites. In the 'Gardeners Chronicle,' 1852, p. 579, is figured a dahlia in which the bracts of the involucre and the scales of the receptacle had all assumed the form, texture, and venation of leaves.[247]
Fig. 127.—Leaf-like bracts in Plantago major.
Fig. 128.—Dahlia. Scales of receptacle leafy.