1911 Encyclopædia Britannica/Polyanthus
POLYANTHUS, one of the oldest of the florists' flowers, is probably derived from P. variabilis, itself a cross between the common primrose and the cowslip; it differs from the primrose in having the umbels of flowers carried up on a stalk. The florists' polyanthus has a golden margin, and is known as the gold-laced polyanthus, the properties being very distinctly laid down and rigidly adhered to. The chief of these are a clear, unshaded, blackish or reddish ground colour, an even margin or lacing of yellow extending round each segment and cutting through its centre down to the ground colour, and a yellow band surrounding the tube of exactly the same hue as the yellow of the lacing. The plants are quite hardy, and grow best in strong, loamy soil tolerably well enriched with well-decayed dung and leaf-mould; they should be planted about the end of September or not later than October. Plants for exhibition present a much better and cleaner appearance if kept during winter in a cold well-aired frame.
For the flower borders what are called fancy polyanthuses are adopted. These are best raised annually from seed, the young crop each year blooming in succession. The seed should be sown as soon as ripe, the young plants being allowed to stand through the winter in the seed bed. In April or May they are planted out in a bed of rich garden soil, and they will bloom abundantly the following spring. A few of the better “thrum-eyed” sorts (those having the anthers in the eye, and the pistil sunk in the tube) should be allowed to ripen seed; the rest may be thrown away. In some remarkable forms which have been cultivated for centuries the ordinarily green calyx has become petaloid; when this is complete it forms the hose-in-hose primrose of gardeners. There are also a few well-known double-flowered varieties.