[Illustration: 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]
[Illustration: FIG. 127.--Leaf-like bracts in _Plantago major_.]
[Illustration: FIG. 128.--Dahlia. Scales of receptacle leafy.]
In _Umbelliferæ_ the substitution of leaves for involucral bracts is not infrequent. It has been observed among other plants in _Angelica Razoulzii_, _Carum carui_, _Daucus Carota_, &c. The scales of the hop (_Humulus Lupulus_) not infrequently manifest this change, as do also the bracts of many amentaceous plants, _e.g._ in the male catkins of the walnut, the female catkins of the alder,[248] of some willows,[249] &c. The bracts of some _Euphorbiaceæ_, as _E. pusilla_, _E. Lathyris_, _E. Cyparissias_, have been observed to undergo a similar alteration.[250]
Amongst monocotyledons an analogous change occurs not unfrequently, as in some commelynaceous plants, _e.g._ _Tradescantia_, in _Musa_, &c.
The spathe of _Arum maculatum_ is sometimes represented by a stalked leaf similar to that which occurs, under ordinary circumstances, in _Spathiphyllum_, but in which genus the spadix is more or less adherent to the leaf-like spathe.[251] In _Schoenus cephalotes_ a similar exaggerated development of the bracts is figured by Rottboell.[252]