New sorts are grown from seeds, which are usually sown as soon as ripe; or they may be kept until the following spring either dry or in stratification. Varieties are commonly increased by offsets, or plants formed at the joints of runners. These runners appear after the fruit is off. If strong plants are desired, the runner should be headed-in, and only one plant allowed to form on each runner. The ground should be soft and somewhat moist, to enable the young plants to obtain a foothold. Plants strong enough for setting are obtained in August and September of the same year in which they start. Ordinarily, the runners will take root without artificial aid; but in hard soils, or with new or scarce varieties, the joints are sometimes held down with a pebble or bit of earth. New varieties are often propagated throughout the season from plants which are highly fertilized, and which are not allowed to fruit. Very strong plants are obtained by growing them in pots. A 3-inch pot is sunk below the runner, and the joint is held upon it by a stone or clod. The runner is then pinched off, to prevent further growth, and to throw all its energy into the one plant. The pot should be filled with soft, rich earth. Shouldered pots are best, because they can be raised more easily than others, by catching the spade or trowel under the shoulder. The plants will fill the pots in three or four weeks, if the weather is favorable. Old tin fruit cans, which have been heated to remove the bottoms, can also be used. Cuttings of the tips of runners are sometimes made and handled in a frame, as an additional means of rapidly increasing new kinds. These cuttings are really the cast-away tips left from the heading-in or checking of the runners. =Strawberry Geranium.= See Saxifraga. =Strawberry Tree.= See Arbutus. =Strelitzia= (Bird of Paradise Flower, Bird's-tongue Flower). _Scitamineæ._ Increased by seeds, which should be sown in light soil, and the pots plunged in moist bottom heat. Also increased by suckers and by division of the old plants. =Streptocarpus= (Cape Primrose). _Gesneraceæ._ Readily propagated by seeds or by divisions. =Strobilanthes=, including Goldfussia (Cone Head). _Acanthaceæ._ Seeds. Cuttings, in any light soil under glass, in heat. =Struthiola.= _Thymelæaceæ._ Seeds, when obtainable. Cuttings in sand under a frame. =Stuartia.= _Ternstrœmiaceæ._ May be increased by seeds and layers, or by means of ripened cuttings, inserted in sand under a hand-glass. Seeds are oftenest used, where obtainable. =Stylidium=, Candollea. _Stylidieæ._ Grown from seeds, or in a few cases, from divisions of the roots. The shrubby kinds may be increased by cuttings. =Stypandra.= _Liliaceæ._ Propagated by divisions. =Styrax= (Storax). _Styraceæ._