SELECT LISTS OF PLANTS. 289 



Propagated by cuttings of the mature shoots set in cold frames, or in a 

 cool greenhouse during the winter months. 



Poinsettia. See Euphorbia. 



Populus (Poplar, Aspen, Cottonwood). A genus of about twenty 

 species, one-half the number indigenous to North America, and one 

 species the Quaking Aspen (P. tremuloides) extending northward to 

 the Arctic Ocean. With few exceptions the Poplars are large, rapid- 

 growing, deciduous trees, thriving in a great variety of soils, but succeed 

 best in one that is rather moist. Extensively cultivated in cold climates 

 for ornament, fuel and shelter. The wood is rather light, of little value 

 for uses, where it is exposed to the weather, but is valuable for fuel, 

 especially where better kinds cannot be obtained. Propagated by seeds, 

 suckers, cuttings of the branches and roots. Varieties are usually prop- 

 agated by cuttings, or by budding and grafting upon stocks of the free- 

 growing species. The seeds are small and produced in pendulous cat- 

 kins, appearing before or at the time of the unfolding of the leaves. The 

 eecds ripen early in the. season, or about two months from the time the 

 flowers appear, and if sown as soon as ripe, they will germinate and pro- 

 duce plants a foot or more in height the first season. Seeds should be 

 scattered over the surface of the seed bed and merely raked in, or a little 

 fine soil sifted over them. If no rain falls soon after the seed is sown, 

 water must be given in liberal quantities until the plants appear and 

 become well established. Cuttings may be made of either one or two- 

 year-old wood, and planted in the fall or spring. 



Potent ilia (Five Finger, Cinquefoil).~An immense genus of the 

 Rose Family, and with few exceptions herbaceous perennials, the 

 species being widely distributed around the world in the Northern Hemi- 

 sphere. The Shrubby Cinquefoil (P. fruticosa), is a low-growing shrub, 

 two to four feet high, with bright yellow floweus ; the plants usually 

 continuing in bloom from early spring until checked by frosts in autumn. 

 This handsome little shrub is indigenous to the colder regions of both 

 North America and Europe, but thrives in much milder climates. Prop- 

 agated by divisions of the clumps, by layers, and cuttings of the mature 

 wood, taken off in the fall, and stored in the usual way until spring. 



Primus (Plum, Prunes). In most of the recent botanical works the 

 Plum and Cherry are placed in the genus Prunus, but the propagator of 

 these fruits is obliged to keep each group distinct or separate, as the true 

 Cherries (Cerasus), and the Plums (Pnmus), cannot be, except in rare 

 instances, interchanged in propagating by budding and grafting, while 

 the Peach, Almond, Apricot and True Plum are so closely allied that any 

 and all of the species and varieties may be employed indiscriminately as 

 stocks for one and another. Still, there is always a preference when, 

 selecting a species or a variety for a stock. (See Fruit Stocks, Chapter 

 XVIII.) Propagated by seed, layers, cuttings of the mature wood, and 

 cuttings of the roots. The latter mode is not recommended, as most of 

 the species and varieties are inclined to produce suckers rather too 



