670 ARBORETUM AND FRUTICETUM. PART III. 



probably be tlieir ultimate height, or whether they can be kept within bounds 

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

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



Oniphalobium, Virgilio, Sophora, several Psoriileae and Cytisi, form a distinct 

 stem: Scholia, Indigofera, Psoralea, ^spalathus, Podaljria, Lipiiria, and 

 Borb6n/«, as well as Cyclopia, 8arcopliyllum, and Rafn/«, 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 ot 

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

 more characteristic masses of flowers. Omphalobium and iSchot/o are of slow 

 growth : 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. In. Ft. In. 



Virgilirt intrusa and cap^nsis <?5 Indig6fera rytisciides - - 8 



If Virgil/a is deeply in- Podalyrir/ styracifoiia - 9 



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



a gum exudes, which is Rafnw (annual growth) 2ft. to 3 



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



Omphalobium - - 12 Liparia sphaj'rica - - 3 



i'oyV/om sylvatica - - 16 //cacia capensis, or nilotica 20 



Psoralea pinnata - - 15 /4cacia cafra - - - 12 



Cyclopia - 4 ft. 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 60 ft., but flowers at the height of 

 15 ft. Erythrina 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 Leguminaceae during win- 

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

 6 ft. or 8 ft. high, and 15 ft. or 20 ft. apart, in the direction of north and south, 

 will leave a space between, which may be covered every autunni 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 by covering with boards or with glass, or even by thatching the soil 

 during heavy rains in autunm, 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 pubh vigorously, and soon have a clothed appearance. 



CHAP. XLII. 



OF THE LIGNEOUS PLANTS BELONGING TO THE ORDER /lOSA'CEi^. 



The term i?osaceae has been applied to this order, because all the species 

 belonging to it agree more or less with the genus /^osa, in essential charac- 

 ters. " It includes many genera belonging to the Linnzean class Icosandria. 



Dhtinctive Clinracteristics, Flowers regular. Calyx, in most cases, with 

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

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



