164 PLANT PROPAGATION 
a heel of the old wood, inserted in pots of sandy soil 
surfaced with a thin layer of pure sand, and plunged in 
bottom heat in a close frame in March or April. The 
winter-flowering P. rosea and its improved form, 
coccinea superba, may be similarly treated. 
PornsetT1aA.—See Euphorbia. 
PoLEMONIUM.—These easily cultivated and mostly 
blue-flowering border plants, commonly known as 
Jacob’s Ladder, are easily increased by division in 
autumn or spring. 
PotyantHus.—The seed of these favourite spring- 
flowering plants should be sown in summer as soon as 
ripe in an outside border, partially shaded and moist. 
Choice sorts are perpetuated by division in autumn. 
POLYGONATUM (SOLOMON’s SEAL).—Easily increased 
by dividing the roots in October or March. 
PoLtyGonumM.—The annual kinds are raised by sowing 
seed in spring; the perennial species by. division in 
autumn or spring. 
POMEGRANATE (Punica granatum). — The single- 
flowered sorts may be raised from seed; the double 
forms and other choice varieties from cuttings, suckers, 
layers, and grafting on seedling stocks of the common 
kind in March. 
PortuLaca.—Those of the grandiflora type grown as 
half-hardy annuals for border flowers maybe sown either 
indoors in March for planting-out later on, or outdoors 
in light, dry soil at the end of April. Exposure to full 
sunshine is absolutely necessary for the full development 
of the brilliant flowers. 
Potato (Solanum tuberosum).—The Potato may be 
raised from seed or cuttings. As is well known, the 
planting of tubers, either whole or cut into pieces each 
