GREEN, viridis.
These colours seem to be appropriated to particular parts of the plant. Thus, white is most common in roots, berries, and the petals of spring flowers; black in the roots and seeds, but rarely in the seed vessel, and scarcely ever in the petals. Yellow is frequent in the antheræ, or tops of the stamina; as likewise in the petals of autumnal flowers, and the compound ligulated flowers of Linnaeus. Red is
common in the petals of summer flowers, and in the acid fruits; blue and violet-colour in the petals; and green in the leaves and calyx, but rarely in the petals. In the interchanging of colours, which in plants is found to depend upon differences in heat, climate, soil, and culture, a sort of elective attraction is observed to take place. Thus, red is more easily changed into white and blue, blue into white and yellow, yellow into white, and white into purple. A red colour is often changed into a white, in the flowers of heath, mother of thyme, betony, pink, viscous campion, cucubalus, trefoil, orchis, fox-glove, thistle, cudweed, saw-wort, rose, poppy, fumitory, and geranium. Red passes into blue in pimpernel. Blue is changed into white in bell-flower, Greek-valerian, bind-weed, columbine, violet vetch, milk-wort, goat's rue, viper's bugloss, comfrey, borrago, hyssop, dragon's head, scabious, blue-bottle, and succory; but it is changed into yellow in crocus. Yellow passes easily into white in meilott, agrimony, mullein, tulip, blattaria or moth-mullein, and corn marigold. White is changed into purple in wood-sorrel, thorn-apple, peas, and daisy.
Although plants are sometimes observed to change their colour upon being moistened with coloured juices, yet that quality in vegetables seems not so much owing to the nature of their nourishment as to the action of the internal and external air, heat, light, and the primitive organization of the parts. In support of this opinion it may be observed that there is far less variety in the colours of roots than of the other parts of the plants; the pulp within the skin being usually white, sometimes yellow, rarely red. That this effect is produced by their small intercourse with the external air, appears from the circumstance, that the upper parts of roots, when they happen to stand naked above the ground, are often dyed with several colours. Thus the tops of sorrel roots turn red; those of turnips, mullein, and radishes, become purple; and many others are converted into green, whilst those parts of the same roots which lie more under ground are commonly white. The green colour is so proper to leaves, that many, as those of sage, the young sprouts of St. John's wort, and others which are reddish when in the bud, acquire a perfect green upon being fully expanded. In like manner, the leaves of the seaside grape (polygonum), which when young are entirely red, become, as they advance in growth, perfectly green; except the middle and transverse ribs, which retain their former colour.
As flowers gradually open and are exposed to the air, they throw off their old colour and acquire a new one; in fact, no flower has its proper colour until it is fully expanded. Thus the purple stock-julyflowers are white or pale in the bud; and in like manner bachelor's buttons, blue-bottle, poppy, red daisies, and many other flowers, though of divers colours when blown, are all white in the bud. Nay, many flowers change their colour thrice successively. Thus, the very young buds of lady's looking-glass, bugloss, and the like, are all white; the larger buds purple or murrey; and the open flowers blue.
With respect to the colours of the juices of plants it may be observed, that most resinous gums are tinctured; some, however, are limpid; and that which drops from the domestic pine is clear as rock-water. The milk of some plants is pale, as in burdock; of others white, as in dandelion, euphorbium, and scorzonera; and of others yellow, as in lovage, and greater celandine. Most mucilages have little colour, taste, or smell. Of all the colours above enumerated, green is the most common to plants, and black the most rare.
Colour, being a quality in plants so apt to change, ought never to be employed in distinguishing their species. These ought to be characterized from circumstances not liable to alteration by culture or other accidents. The same inconsistency of colour observed in the flowers, is likewise to be
Colour. found in the other parts of plants. Berries frequently change from green to red, and from red to white. Even in ripe fruits, the colour, whether white, red, or blue, is apt to vary; particularly in apple, pear, plum, and cherry trees. Seeds are more constant in point of colour than the vessel which contains them. In the seeds, however, of the poppy, oats, pea, bean, and kidney-bean, variations are frequently observed. The root, too, although not remarkably subject to change, is found to vary in some species of carrot and radish. Leaves frequently become spotted, as in a species of orchis, hawk-weed, ranunculus, knot-grass, and lettuce; but seldom relinquish their green colour altogether. Those of some species of amaranthus, or flower-gentle, are beautifully coloured. The spots which appear on the surface of the leaves are of different colours, liable to vary, and not unfrequently disappear altogether. The leaves of officinal lung-wort, and some species of sow-bread, sorrel, trefoil, and ranunculus, are covered with white spots; those of dog's-tooth violet, with purple and white; those of several species of ranunculus and orchis, with black and purple; those of amaranthus tricolor, with green, red, and yellow; those of ranunculus acris, and a species of bog bean, with red or purple. The under surface of the leaves of some species of pimpernel and the sea-plantain is marked with a number of dots or points; a white line runs through the leaves of Indian reed, black-berried heath, and a species of Canary grass; and the margin or brim of the leaf, in some species of box, honeysuckle, ground ivy, and the evergreen oak, is of a silver-white colour. The whole plant is often found to assume a colour that is unnatural or foreign to it. The varieties in some species of eryngo, mug-wort, orach, amaranthus, purslane, and lettuce, furnish examples of this.
Such being the inconstancy of colours in all the parts of the plant, specific names derived from that quality are very properly deemed erroneous by Linnæus; whether they respect the colour of the flower, fruit, seeds, roots, leaves, or express in general the beauty or deformity of the entire plant, with a particular view to that circumstance. But of this impropriety, committed by former botanists, Linnæus himself is not always guiltless. Thus the two species of sarracena, or the side-saddle flower, are distinguished by the colour of their petals into the yellow and purple sarracena; although the shapes and figure of the leaves afford much more constant as well as striking characters. The same may be said of his Lupinus albus and luteus; Reseda alba, glauca, and lutea; Angelica atropurpurea; Dictamnus albus; Lamium album; Selago coecinea; Sida alba; Passiflora rubra, lutea, incarnata, and caerulea; and of many others, in which the specific name is derived from a character or quality that is so liable to vary in the same species.
In conclusion, of all sensible qualities, colour is the least useful in indicating the virtues and powers of vegetables. The following general positions on this subject are laid down by Linnæus, and seem sufficiently confirmed by experiment:—A yellow colour generally indicates a bitter taste; as in gentian, aloe, celandine, turmeric, and other yellow flowers. Red indicates an acid or sour taste; as in cranberries, barberries, currants, raspberries, mulberries, cherries, the fruit of the rose, sea-buckthorn, and service-tree. Herbs which turn red towards autumn have likewise a sour taste; as sorrel, wood-sorrel, and bloody-dock. Green indicates a crude alkaline taste, as in leaves and unripe fruits. A pale colour denotes an insipid taste; as in endive, asparagus, and lettuce. White promises a sweet luscious taste; as in white currants and plums, sweet apples, &c. Lastly, black indicates a harsh, nauseous, disagreeable taste; as in the berries of deadly nightshade, myrtle-leaved sumach, herb-Christopher, and others—many of which are not only unpleasant to the taste, but pernicious and deadly in their effects.