ring
matter proper to the flower, or by an actual development of leaf-like
organs in the room of the petals--frondescence. Morren[374] judiciously
proposed to keep these two conditions separate, calling the one
virescence, the other frondescence (see p. 241).

Many of the cases recorded as reversions of the parts of the flower to
leaves are simply instances of virescence; indeed, it is not in all
cases easy to distinguish between the two states. The examination of the
arrangement of the veins is often of assistance in determining this
point; for instance, if, under ordinary circumstances, the venation of
the petal be such as is characteristic of the sheath of the leaf, while
in the green-coloured flower of the same species the venation is more
like that which belongs to the blade of the leaf, the inference would,
of course, be that the green colour was due to frondescence or phyllody.

The persistence or duration of petals is often increased when they are
subject to this change; instead of falling off speedily they become
persistent when so affected.

Some flowers are more liable to virescence than others. The common
honeysuckle, _Lonicera Periclymenum_, is one of these, and it is
noticeable in this plant that the calyx remains unaffected--a
circumstance which Morren says shows the distinctness of virescence from
frondescence; for, in this instance, we have the most foliaceous portion
of the flower remaining unchanged, while the corolla and other organs,
usually less leaf-like in their nature, assume a green colour; but this
may rather be attributed to the axial nature of the so-called adherent
calyx. The stamens in these green-flowered honeysuckles are usually
green also, but with abortive anthers, and the pistil also is in a
rudimentary condition. _Umbelliferae_ are not unfrequently subject to
this change, _e.g._, _Torilis Anthriscus_, _Daucus Carota_, _Heracleum
Sphondylium_, _Carum carui_, &c. _Primulaceae_, again, are frequently
subject to virescence. Among _Compositae_ the following species are
recorded as having had green flowers--_Cirsium tricephalodes_, _Senecio
vulgaris_, _Calendula officinalis_, _Pyrethrum Parthenium_, _Carduus
crispus_, _Hypochaeris radicata_, _Hieracium prealtum_, _Cirsium
arvense_, _Coreopsis Drummondi_.[375] In _Ranunculaceae_ virescence has
been observed in _Delphinium elatum_, _crassicaule_ and _Ajacis_,
_Anemone hortensis_ and _nemorosa_, _Aquilegia vulgaris_, _Ranunculus
Philonotis