260 ARBORETUM ET FRUTICETUM BRITANNICUM. 



the attacks of insects and diseases. They almost all require a free loamy soil, 

 not overcharged with moisture, and rich rather than poor ; and, while all the 

 species are increased by seeds, which, for the most part, are produced freely in 

 Britain, or by cuttings of the roots, almost all the varieties are best increased 

 by grafting or budding ; and not, as in some other orders, with equal ease by 

 cuttings of the shoots, or by layers. 



With reference to landscape-gardening, all the rosaceous trees have three 

 properties which deserve to be kept constantly in viesv by the improver of 

 grounds: 1st, they never attain a large size ; 2d, they attain their natural size 

 and shape in a very few years, in good soil not requiring more than from 

 10 to 20 years ; and 3d, they sooner take the character of old trees than the 

 trees of any other natural order of ligneous plants. A few exceptions may be 

 taken from different orders, such as the common field maple, the common 

 laburnum, &c. ; but we know of no natural order, in which, like the Rosaceas, 

 all the trees are low or middle-sized, and all take the character of age while 

 comparatively young. Hence their value in laying out small places, where 

 the object is to make a new place appear old, or a small place appear large, 

 and at the same time to combine character of form with beautiful blossoms 

 in spring, and showy (fratas'gus, Cotoneaster, and Ameldnchier) or useful 

 (Pyrus and Prunus) fruit in autumn. 



The genera are included by DeCandolle and G. Don in five tribes ; and the 

 following are their names and distinctions : 



Sect. I. ^MYGDA V LE: JllSS. 



Sect. Char. Fruit a drupe ; the nut 2-ovuled, I 2-seeded. Style terminal. 

 Calyx deciduous. Leaves feather-nerved, undivided, serrate, with the 

 lower serratures or the petioles glanded. Stipules not attached to the 

 petiole. Kernel containing more or less of hydrocyanic acid : chiefly 

 fruit trees. 



^MY'GDALUS Tourn. Covering of nut not fleshy ; nut even, or perforated 

 Young leaves folded flatwise. Flowers almost sessile, solitary or twin, 

 protruded before the leaves. 



PE'RSICA Tourn. Covering of nut very fleshy ; nut wrinkled. The- charac- 

 ters of the other parts described under Amygda\\is are the same in Persica. 

 /(RMENI'ACA Tourn. Covering of nut fleshy ; nut furrowed at both edges, in 

 the other parts even. Young leaves with their edges rolled inwards. 

 Flowers almost sessile, solitary or a few together, protruded before the 

 leaves. 



PRU^NUS Tourn. Covering of nut fleshy ; nut indistinctly furrowed at the 

 edges, in the other parts even. Young leaves with the edges rolled inwards. 

 Flowers upon pedicels, in groups resembling umbels, and produced before 

 or after the leaves. 



CE'RASUS Juss. Nut subglobose, even, its covering fleshy. Young leaves 

 folded -flatwise. Flowers upon pedicels, either in groups resembling umbels, 

 and produced before the leaves, or in racemes terminal to the shoots, pro- 

 truded along with them. 



Sect. II. PIR^EE V JE Dec. 



Sect. Char. Fruit of 5, or fewer, capsular carpels, which are distinct from 

 the calyx (which is persistent in Spirae v a, and, perhaps, in the other 

 genera), and, in most cases, from each other: each contains 1 6 seeds. 

 Style terminal. Low deciduous shrubs. 



PU'RSHL* Dec. Stamens about 20. Carpels 1 2, ovate-oblong. 

 KE'RRIA Dec. Stamens about 20. Carpels 5 8, distinct. 

 SPIRJE V A L. Stamens 10 50. Carpels 1 to several, distinct ; stipitate ; each 

 includes 2 6 seeds, affixed to the inner suture. 



Sect. III. POTENTI'LLE,E Juss. (Synon. Dryadeae Vent.) 

 Sect. Char. Fruit an aggregation of carpels; their integuments dry or 



