Pyrethrum parthenium plena, - or Double Feverfew, - is an ornamental plant, with pure white flowers, from June to September; two feet high. It is frequently kept in green-houses, but stands out all winter with a little protection. It is raised from cuttings, or by dividing the roots. When raised from seed, most of the plants will be worthless, not much better than weeds, as there is no beauty in the single flowers.