290 PBOPAGATION OF PLANTS. 



freely. Some of the varieties of the common European Hum (P. domes- 

 tied), are readily inereased by cuttings of the ripe wood treated in the 

 same manner as usual with the Currant and Gooseberry. The Myrabo- 

 lan Plum, so largely used in France for stocks, may be propagated by 

 cuttings ; also many of our choice garden varieties. The seeds or Plum 

 stones should be placed where they will be kept moist and cool during 

 the winter months, and if they freeze while moist, the shell will open all 

 the more readily when planted out in the spring. 



Pseudotsuga (Douglass Spruce). — ^A species of conifers found in the 

 Eocky Mountain regions ; closely allied to the True Spruces (JPlcea). It is 

 a hardy tree, thriving in our Northern Atlantic States. Propagated by 

 the same modes as the more common species of the Spruce. , 



Ptelea (Hop Tree). — A small genus of North American shrubs or 

 small trees. Two species ai-e native of the United States ; one, the 

 P. irlfoliata, is common in the Middle and Western States, and the other 

 one, P. angustifolia, from Texas westward to Calif oi-nia. The broad, oblong 

 winged seed is sometimes used as a substitute for the common Hop. 

 Propagated by layers and seeds sown in autumn, or preserved in sand 

 until spring. 



Pterocarya (Winged Walnut). A small genus of deciduous trees 

 from Asia, closely allied to the Hickories (Carya) and Wabiuts (Juglans). 

 Propagated by seed and layers, also by suckers that usually spiing up 

 about the main stem, these producing roots sufficient to admit of allow- 

 ing them to be taken oft and planted out with safety. 



Pterostyrax (Winged Storax). — ^An ornamental deciduous shrub or 

 small tree from Japan, bearing creamy-white, fragrant flowers. It be- 

 longs to the Storax Family (Styracaeecs), and is closely related to the 

 Halesias. Propagated by seeds, layers, and by gi-afting on the Halesia. 

 Veneer grafting under glass in late summer is the most certain mode. 



Pwnica (Pomegranate). — This is one of the few fruits that appears 

 to have come down to us from very ancient times, and almost in its prim- 

 itive condition. The Promegranate tree is of a rather bushy habit, grow- 

 ing from twenty to thirty feet high in tropical countries, although it is 

 readily controlled by pmning, and may be trained in the form of a small 

 shrub. It is extensively cultivated throughout the semi-tropical and 

 tropical countries of the Old and New World, and highly prized as an 

 ornamental and fruit-bearing tree, in oui' Southern States. The fruit is 

 as large as an ordinary apple, and the numerous seeds imbedded in or 

 surrounded with a juicy pulp ; it is used in hot climates for making cool- 

 ing drinks. There are several varieties in cultivation, aU readUy prop- 

 agated by seeds, layers and cuttings. Very scarce varieties are sometimes 

 propagated by grafting on the more common sorts. 



Quercus (Oak). — A very large genus of evergreen and deciduous 

 trees and shrubs. About forty species are found within the limits of the 

 United States, and more than two hundi-ed additional species are in- 

 digenous to other countries of the northern hemisphere^ They are for 



