670 ARBORETUM AND FRUTKETUM. PART III. 



probablv be their ultinuite height, or whether they can be kept within bounds 

 bv pruning, without injury or total prevention of flowering. This point re- 

 quires consideration, or tlie plants are likely to become nuisances. 



Omphalobium, Virgilw, Sujrfijjfa, several Psoraleaeand C'ytisi, form a distinct 

 stem : Schorr, Indigofera, Psoralea, ^spalathus, PodalvYw, Liparia, and 

 liorbon/c/, as well as Cyelopia, Sarcophyllum, and RafruV/, form branching 

 shrubs from the collar. In the three last-mentioned genera, this habit should 

 be encouraged as much as possible, by cutting them down to the ground ; 

 which occasions the larger growth of the collar: and, in old plants, the ap- 

 pearance of nakedness would be but temporary; while the quick growth of 

 numerous shoots would soon form them into dense bushes, and stronger and 

 more characteristic masses of flowers. Omphalobium and Schot/a are of slow 

 urowth : planting them under the shade of others will draw them up to a re- 

 quisite height without injury. 



Mr. Bowie gives the following list of the average height which several 

 species attain in their native habitations, as a guide to the cultivator in 

 planting : 



Ft Iii. Ft. In. 



Virgilirt intrusa and cape'nsis 25 Indigofera cytisoMes - 8 



If Virgil/fl is deeply in- Podalyria Atyracifolia- - 90 



jured in the old wood, yJspalathus - 6 in. to 4 



a iium exudes, which ia Rafn/fl (annual growth) 2 ft. to 3 



used as gum Arabic. Sarcophy Hum (annual growth) 1 6 



Omphalobium - -120 Liparia splue'rica - 30 



Sujj/n'ira sylvatica - 16 Acacia capensis, or nilotica 20 



Psoralea pinnata - 15 Acacia cafra - - 12 



Cyclopia 4ft. to 10 



The latter thrives best by being cut down, and confined as a shrub to 6 ft. 

 They both yield the gum Arabic. 



Erythrina cafra attains the height of CO ft., but flowers at the height of 

 15ft. Ervthrina nana, introduced by Mr. Bowie into England in 1823, 

 flowers at 2 ft. ; and may be considered as half-shrubby, as it scarcely ever 

 attains a permanent stem : it is a desirable plant. 



A portable house, for the protection of half-hardy Leguminacca? during win- 

 ter, may be made in various forms, at very little expense. Two parallel walls, 

 (> ft. or 8 ft. high, and lo ft. or 20 ft. apart, in the direction of north and south, 

 will leave a space between, which may be covered every autumn with tem- 

 porary rafters, on which may be placed the sashes of hot-beds not in use, alter- 

 nating with boards. If moisture has been withdrawn from the soil, by drain- 

 age, and bv covering with boards or with glass, or even by thatching the soil 

 during heavy rains in autumn, so as to facilitate the ripening of the wood, 

 there will be no difficulty in keeping the plants alive; and when they are cut 

 in, in spring, they will push vigorously, and soon have a clothed appearance. 



CHAP. XLII. 



OF THE LIGNEOUS PLANTS BELONGING TO THE ORDER 



Tin: term /^osaccaj has been applied to this order, because all the species 

 bcloi)L, r ini: to it atiree more or less with the genus /i'o>.a, in essential charac- 

 ters. It includes many genera belonging to the Linn;ean class Icosiindna. 



l)ix(incth'c C/ifiracfcrisfirSt Flowers regular. Calvx, in most cases, with 

 .') lobes, the odd one posterior to the axis of inflorescence. Petals and 

 stamens arising from the calyx. Stamens, for the most part, numerous. 



