Encyclopaedia of Gardening 253 



in late summer and the plants top-dressed to encourage fresh shoots 

 from the base. Beautiful beds of Pentstemons may be had by 

 setting the plants 2 ft. apart; or groups may be formed in the 

 borders. They bear large, bell-shaped flowers on long, arching 

 stems. The following species are good for the rockery: azureus, 

 i ft., blue; barbatus (syn. Chelone barbatus Botanical Register, 

 t. 1 1 6), 3 ft., scarlet, Torreyi is a variety; glaber, i ft., blue 

 (Botanical Magazine, t. 1672); Hartwegii, 2 ft., scarlet; gentian- 

 oides, 3 ft., violet; Menziesii, 6 ins., purple and red, Scouleri is a 

 mauve variety. Azureus, Hartwegii, and gentianoides are not 

 quite so hardy as barbatus, glaber, and Menziesii. 



Perennial. A perennial is a plant that lives more than two years 

 (cf. Annual and Biennial). When flower gardeners speak of peren- 

 nials they have herbaceous perennials in mind, but, strictly speak- 

 ing, trees and shrubs are also perennials. 



Pereskia. See Cactus. 



Pergola. See Flower Garden. 



Perilla (perill-a. Ord. Labiatae). Half-hardy annuals, of which 

 nankinensis is grown in flower gardens for its purple foliage. For 

 culture, see Annuals. 



Periploca (perip-loca, from periploke, intertwining. Ord. Ascle- 

 piadeae). One species only is grown to any extent, and that is 

 Graeca, a quick-growing climber with peculiar greenish-purple 

 flowers, suitable for pergolas and arbours. It is hardy, and blooms 

 in summer. It is not particular as to soil. Propagation is by cut- 

 tings under a hand-light, or by layers, in autumn (see the Botanical 

 Magazine, t. 2289). 



Peristeria, Dove Orchid (periste-ria, from peristera, owing to the 

 form of the column. Ord. Orchidaceae) . A small genus of Orchids, 

 liking a light hothouse. Elata, the Dove Orchid, with its interesting 

 and fragrant white, purple-spotted flowers in summer, is the best 

 known (see the Botanical Magazine, t. 31 16). It forms large pseudo- 

 bulbs. It should be grown in a mixture of fibrous loam, peat, and 

 leaf mould in equal parts, with sand, and may be propagated by 

 division. A good deal of water is needed while they are in growth, 

 but little when they are at rest. 



Peristrophe (peris-trophe, from peristrophe, turning round, in 

 allusion to the reversed corolla. Ord. Acanthaceae). Speciosa 

 (syn. Justicia speciosa) is a pretty winter-blooming plant, well 

 worth growing by all who have a warm greenhouse (see the Botanical 

 Magazine, t. 2722). It grows about 2 ft. high, and bears its purplish- 

 red flowers freely. Loam, with sand and a third each of leaf mould 

 and decayed manure, suits. Propagation is by cuttings inserted 

 in a warm case in spring. 



Periwinkle. See Vinca. 



Pernettya (pernet-tya, after Don Pernetty. Ord. Ericaceae). 

 Pretty evergreens, hardy except in very cold, exposed places, but 

 of slow growth and quite suitable for pot culture. The most popular 

 species is mucronata, the charm of which lies in the pretty berries 



