The dwarf almonds (_Amygdalus_) are increased by seeds, divisions, cuttings, and by budding upon seedling plum or peach stocks; also by root-cuttings. Peach stocks give larger trees at first than plum stocks, but the trees are not so long-lived. Perhaps ten years may be considered the average life of most ornamental almonds upon the peach, while upon the plum they may persist twenty-five years or more. The ornamental cherries, peaches, etc., are propagated in essentially the same manner as the fruit-bearing varieties. See Almond, Apricot, Cherry, Peach, Plum. _P. Lauro-Cerasus_ and _P. Lusitanica_, the cherry laurel and Portugal laurel, may be propagated by short cuttings of ripened wood, in a cool greenhouse in autumn. _P. Pissardii_ is said to be easily propagated by cuttings of the soft wood. This method succeeds well with many of the double-flowering plums and cherries, if the wood is grown under glass. =Pseudotsuga.= _Coniferæ._ Propagated the same as Abies, which see. =Psidium.= See Guava. =Psoralea.= _Leguminosæ._ Seeds, divisions and cuttings of growing shoots, placed under glass. The tubiferous species, as the pomme blanche or Indian potato (_P. esculenta_) are increased by tubers or divisions of them. =Ptelea= (Hop-tree). _Rutaceæ._ Increased by seeds, sown in autumn or stratified, or by layers. The varieties may be grafted on the common forms. =Pteris= (Brake, Bracken). _Filices._ Easily grown from spores. See Ferns. =Pterocarya.= _Juglandeæ._ Increased by seeds, suckers and layers. =Ptychosperma=, Seaforthia (Australian Feather-palm). _Palmæ._ Seeds. =Pulmonaria.= See Mertensia. =Pumpkin= (_Cucurbita_, three species). _Cucurbitaceæ._ Seeds, when the weather is settled. =Punica.= See Pomegranate. =Puschkinia=, Adamsia. _Liliaceæ._ Increased by dividing the bulbs, which should be done every two or three years. =Pyrethrum.= See Chrysanthemum. =Pyrola= (Shin-leaf, Wintergreen). _Ericaceæ._ Propagated by division; very rarely from seeds. =Pyrus.= _Rosaceæ._ The ornamental species and varieties of apples and crabs are budded or grafted upon common apple stocks. The mountain ashes are grown from stratified seeds, which usually lie dormant until the second year, or the varieties are budded or grafted upon stocks of the common species (_P. Aucuparia_). Layers and green cuttings are occasionally employed for various species and varieties of pyrus. See also Apple, Pear, Quince. It is a good plan to obtain stocks as nearly related to the plant which is to be propagated as possible; _e. g._, Parkman's pyrus does better on _P. floribunda_ than on the common apple stock. =Quamoclit.= See Ipomœa. =Quassia.= _Simarubeæ._ Cuttings of ripe shoots under glass. =Quercus= (Oak). _Cupuliferæ._