166 PLANT PROPAGATION 
plunged in a bottom heat of 75 degrees, watered, the 
foliage allowed to dry, then kept close and shaded until 
rooted. Some remove a few of the bottom leaves from 
old plants after flowering and earth up the stems to 
induce roots to form, so that the cuttings may be 
taken off already rooted. They flourish better when 
afforded a little more heat than is required by the single 
kinds. 
The hardy Primroses grow freely from seed sown 
soon after ripening, but old seed will sometimes lie 
dormant for a year before germinating. Choice named 
varieties are divided, by which means their distinctive 
characters are retained. 
PruNnus.—Many of the ornamental species of this 
genus can be propagated by cuttings of tolerably firm 
shoots inserted in pots of sandy soil in a cold frame in 
autumn; by budding on stocks of the Common or 
Myrobalan Plum in July and August, and by layering 
branches in autumn and spring. 
PuLMonaRIA (LUNGWoRT).—These border perennials 
are easily increased by division in early spring. 
PyRETHRUM.—Closely allied to Chrysanthemums and 
much grown for cut-flowers, a large number of beautiful 
varieties are mostly increased by division of the roots in 
March and by seed sown in gentle heat about the same 
time to provide material for planting out in June. Golden 
Feather seed is sown in a little warmth in March, and 
when big enough pricked out in boxes to be hardened 
off for planting out in May. 
Pyrus.—The many ornamental kinds of this genus, 
grown for their abundant blossoms and bright-coloured 
fruits, are propagated by seeds, cuttings, budding, and 
grafting, like Apple and Pear-trees. 
