Prunus.—­Beautiful early-flowering trees, which will grow in any soil, and can be increased by seeds or suckers.

Ptelia Trifoliata (Hop Tree).—­This is very suitable for planting on the borders of still waters, where its long frond-like leaves, which turn to a golden yellow in autumn, produce a fine effect.  It blooms in June, and is propagated by layers.  Height, 10 ft.

Pulmonarias (Lungworts).—­Hardy perennials that require but little attention; may be grown in any common soil, and propagated by division at any time.  They flower in April and May.  Height, 1 ft.

Pumilum.—­See “Heleniums.”

Pumpkins.—­Valuable for soups and pies in winter, and in summer the young shoots are an excellent substitute for Asparagus.  For their cultivation, see “Gourds.”

Punica Granata Nana.—­A greenhouse deciduous shrub which flowers in August.  The soil in which it is placed should be a light, rich loam.  It can be most freely multiplied by layers, and cuttings will strike in sand under glass.  Height, 4 ft.

Puschkinia (Striped Squills).—­This charming bulbous plant may be grown in any light, rich mould, provided it is drained well.  The bulbs may be separated when the clumps get overcrowded, late in summer, after the tops have died down, being the most suitable time to do so.  If planted in a warm position it will begin to flower in March, and continue in bloom till May.  Height, 8 in.

Pyrethrum.—­The greenhouse kinds grow in any rich soil, and young cuttings planted under glass root readily.  The hardy kinds are not particular as to soil so long as it is not cold and wet, and are increased by seeds sown in heat in February if wanted for early use, or in the open during March and April for later growth.  The crowns may be divided either in autumn or spring:  each eye or bud will make a fresh plant.  Young plants produced in this way in the autumn require the protection of a frame during the winter.  They flower in July.  Height varies from 6 in. to 3 ft.

Pyrola.—­A handsome hardy plant, suitable for a moist, shady situation.  It is raised from seed, or will bear dividing, but is rather hard to grow.  Height, 6 in.

Pyrus Japonica.—­See “Cydonia.”

Q

Quaking Grass.—­See “Briza.”

Quercus Ilex.—­A handsome evergreen Oak, delighting in a deep, loamy soil.  It is propagated by seed sown as soon as it is ripe.

Quinces.—­Plant in autumn in a moist but well-drained soil.  Cuttings of stout stems 6 or 8 in. long, firmly and deeply planted in a shady situation, mulched with leaf-mould, and kept watered in dry weather, will take root; but the surest method of propagation is by layers, pegged down in the soil and detached the following year.  A good watering with liquid manure will swell the fruit to a large size.  Keep the branches well thinned out and cut them regular, so as to let in light and air and form nicely shaped trees.  The pruning should be done as soon as the leaves fall.  In orchards they should stand 1 rod apart.