=Pine-apple= (_Ananas sativa_). _Bromeliaceæ._ Pine-apples very rarely produce seeds, but when they are produced they are sown for the purpose of obtaining new varieties. The pine-apple is usually increased by suckers and "crowns." If the root is left in the ground after the pine is removed, suckers will start from it. The root is then taken up and cut into as many pieces as there are suckers, each piece being then permanently planted. The crown of the fruit and the various offsets or "crownlets," which appear on the sides and base of the fruit, may be removed and used as cuttings. These offsets are commonly used in greenhouse propagation. It is the usual practice to allow them to dry several days before they are planted, and in pine-apple regions they are often exposed to the sun for several weeks. This operation is unnecessary, however, although it is not objectionable. A good way to start the offsets is to pull off the lowest leaves and insert the offsets in damp moss in shade--giving bottom heat for greenhouse work--and as soon as roots begin to form, which will occur in from two to six weeks, plant them out permanently. In the tropics fruit can be obtained in 20 months after the offsets are transplanted; but fruit-bearing is often delayed three or four years under poor treatment. =Piney.= See Pæony. =Pinguicula= (Butterwort). _Lentibularieæ._ The hardy and greenhouse species are increased by seeds. divisions, or by leaf cuttings. =Pink= (Dianthus, various species). _Caryophylleæ._ Seeds and divisions. Best results are obtained by raising new plants from seed every two or three years. Seeds are usually sown where the plants are to remain; or they may be sown in a cold-frame and transplanted. =Pinus= (Pine). _Coniferæ._ Seeds, which should be kept dry over winter, are commonly employed. These are often started in pots, but for most species they are sown in well-prepared beds out-doors. The seedlings must usually be shaded the first season. Varieties, as also species which do not produce seed freely, may be grafted upon stocks of white or Austrian pine or other species. This grafting may be done upon the tips of growing shoots early in the season (page 90), but it is oftener performed upon potted plants by the veneer method. =Piper=, Cubeba (Pepper, Cubeb). _Piperaceæ._ Seeds. All are increased by means of cuttings of the growing shoots, inserted in sandy soil under glass. =Piscidia= (Fish Poison-tree, Jamaica Dogwood). _Leguminosæ._ Seeds. Cuttings of growing shoots under glass. =Pistacia.= _Anacardiaceæ._ Seeds, cuttings and layers. The pistacio-nut or "green almond" (_P. vera_) is usually grown from seeds, which are planted where the trees are to stand. It is sometimes grafted upon _P. terebinthus_, to give it greater vigor.