314 



THE GARDENER'S ASSISTANT. 



P. fastigiata (P. pyramidalis), Lombardy Poplar. — 

 This well-known tree, so remarkable for its slender, erect, 

 lofty form, is a variety of P. nigra. 



P. grandidentata. — Leaves large, coarsely toothed. 

 North America, 1772. 



P. monilifera, Necklace Poplar. — This has very long 

 female catkins. Canada, 1769. 



P. nigra, Black Italian Poplar. — A rapid-growing tree 

 from 50 to 80 feet high, doing well in most situations. 

 Its leaves expand late. 



P. tremula, Aspen. — Both the type and a variety called 

 pendula are trees of elegant habit. 



Potentilla fruticosa. — A native undershrub about 

 3 feet high, with three to five-foliolate leaves, and yellow 

 flowers in July and August, continuing long in blossom. 

 The variety tenuiloba is the most ornamental. 



P. glabra is a pretty dwarf shrub with smooth leaves 

 and stems, and white flowers. Siberia, 1818. 



Peinos glaber. — An evergreen shrub growing about 4 

 feet high, with small lanceolate leaves, and white flowers 

 in July or August, succeeded by black berries. North 

 America, 1759. 



P. vcrticillata, Black Alder. — A North American shrub, 

 closely allied to the Holly but deciduous. Leaves hairy, 

 not prickly ; flowers small, white, followed by red berries. 

 1736. 



Prunus. — This genus includes Amygdalus (Almond), 

 Persica (Peach), Cerasus (Cherry), besides the true Plums; 

 for the purposes of this work we have, as a more con- 

 venient arrangement, kept up the older distinctions. 



P. cerasifera, Myrobalan Plum. — A small tree, probably 

 a native of the Caucasus. It flowers in April, and its 

 blossoms are white. Var. atropurpurea, now widely 

 known as P. Pissardi, is one of the most valuable of 

 recently - introduced trees. It produces an abundance 

 of delicate rosy flowers in 

 March, followed by the 

 claret-coloured foliage which 

 maintains throughout the 

 summer and autumn a more 

 or less reddish -purple tinge. 



P. spinosa, Blackthorn or 

 Sloe. — The double-flowered 

 form of this native tree is 

 very handsome. It flowers 

 at the same time as the wild 

 plant. 



P. triloba (Amygdalopsis 

 Lindleyi) (fig. 384). — An 

 early spring • flowering shrub, 

 the rosy -white flowers of 

 which are usually partly or 

 wholly double. China, 1857. 



Besides the above the fol- 

 lowing are well worth culti- 

 vation : — P. Murne, a new 

 introduction from Japan; P. 

 dasycarpa ; P. divaricata, a 

 Caucasian small tree bearing 

 a wealth of white flowers in 

 early April, and allied to the 

 Myrobalan Plum. 



Ptelea trifoliata, Hop- 

 tree. A small tree 10 to 15 

 feet high, with trifoliate leaves and clustered greenish 

 flowers, followed by winged hop-like seed-vessels. North 

 America, 1704. There are varieties with variegated 

 and golden foliage and fastigiate branches. 



Pterocarya caucasica (P. fraxinifolia). — A very orna- 

 mental tree of moderate dimensions, belonging to the 

 Walnut tribe. It has pinnate leaves, and the small 

 flowers are borne in catkins, succeeded by winged seed* 



Fig. 384.— Prunus triloba. 



Fig. 385.— Pyrus arbutifolia. (§.) 



vessels. In low, humid situations, and in a rich soil, 

 it does not sufficiently ripen its wood to withstand the 

 frosts, the tips of the branches being often injured, like 

 those of Ailantus glandrdosa. Caucasus, 1782. 



Pterostyrax. — A genus of shrubs or small trees nearly 

 allied to the Halesias but natives of Japan. 



P. hispidum. — A handsome species with large cordate 

 leaves and pendulous racemes of small white flowers. 

 1875. P. corymbosum has rose-tinted flowers ; the ovate 

 leaves are rounded at the base. 



Punica Granatum. — The Pomegranate succeeds very 

 well in warm situations in the south and west, but it 

 requires additional protection inland and northward. 

 There are double, scarlet, and striped-flowered varieties. 

 Southern Europe, 1648. 



Pyrus. — Small or medium-sized trees and shrubs, some 

 of which are desirable on account of their beautiful masses 

 of blossom, others for the ornamental character of their 

 fruits. 



P. arbutifolia, Chokeberry (fig. 385). — This is a semi- 

 shrubby species attaining sometimes a height of 10 feet. 

 Its leaves are oblong and woolly beneath; the flowers are 

 borne in early summer and are white. North America, 

 1700. 



P. Aria, White-Beam Tree. — Leaves divided, densely 

 woolly and silvery beneath ; fruit bright-red, very orna- 

 mental. Very variable in the lobing of the leaf. In- 

 digenous. This species may be taken as the type of an im- 

 portant section of the genus, characterized by usually large 

 leaves more or less silvery beneath. P. vestita, P. Aria 

 var. lutescens, and P. lanata are amongst the best of them. 



P. Aucuparia, Mountain Ash or Rowan-tree. — A good 

 tree for exposed situations. It has pinnate leaves, and 

 its bright-red bunches of fruit are very striking. Indi- 

 genous. There are pendulous and variegated forms, also 



