Seeds, sown in spring where the plants are to remain. =Onosma= (Golden Drop). _Boragineæ._ Seeds, sown in the open in spring. Perennial species by cuttings in summer. =Opuntia= (Prickly Pear, Indian Fig). _Cacteæ._ Seeds grow readily, sown as soon as ripe in ordinary sandy soil, either in the house or out-doors. The joints grow readily if laid on sand. It is customary to allow these cuttings to dry several days before planting them. See also Cactus. =Orach= (_Atriplex hortensis_). _Chenopodiaceæ._ Seeds, sown where the plants are to stand. =Orange= (_Citrus Aurantium_). _Rutaceæ._ Orange stocks are grown from seeds, which should be cleaned and stratified in sand or other material, until sowing time. The seeds should not be allowed to become hard and dry. Some prefer to let the seeds sprout in the sand and then sow them in the nursery, but they must be carefully handled. The seeds are usually sown in seed beds, after the manner of apple seeds, and the seedlings are transplanted the next fall or spring into nursery rows. Care must always be exercised in handling orange plants, as they are often impatient of transplanting. Oranges grow readily from cuttings, although cuttage is not often practiced. Green cuttings, handled under a frame, give good results. Mature wood, either one or two years old, can be treated after the manner of long grape cuttings. They must have an abundance of moisture. Layers are sometimes made.