CHAP. XLII. 



ftOSA CE^. PU RSH/^. 



721 



Soil, Situation, S^c. A deep, free, dry soil, and a sheltered situation, are 

 essential to this species ; which, north of London, as already observed, will 

 be safest placed against a wall, or, probably, grafted on the Portugal laurel. 

 In the London nurseries, it is propagated from seeds ; and plants, of which 

 there are now (1836) abundance in the Fulham, Epsom, and Milford Nur- 

 series, are \s. 6d. each. 



App. i. Other Species ofCerastis. 



In De Candolle's Prodromus, and in Don's Miller, two West Indian, and four South American, 

 species are described ; but only two of these (C. spha;rocarpa Lois., P. sphferocarpa Sivartz, Don's 

 Mill., ii. p. 516. ; and C. occidentiilis Lois., and Don's Mill., ii. p. 516., P. occidentJllis Swartx) liave 

 been introduced into Britain. They are both considered hot-house plants, but might, probably, be 

 acclimatised. Rafinesquc, under the article PrCinus, in his Medical Flora, vol. ii. p. i5S., says that he 

 has prepared a monograph of 40 wild American species of /"riinus ; under which genus, with Lin. 

 njBus, he includes both plums and cherries ; only 25 of which, he says, are described by authors : 

 but we are not aware that any work of this description has been published. 



Sect. II. SpinjEF^jE. 

 Genus VI. 



-# 



PU'RSH/^ Dec. The Purshia. Lin. Syst. Icosandria Monogynia. 



Idenlification. Dec. in Trans, of Lin. Soc, 12. p. 157. ; Prod., 2. p. 541. ; Lindl. in Bot. Reg., t. 1446. : 

 Don's Mill., 2. p. 517. 



Synonyme. Tigarea Ph. Fl. Amer. Sept., 1. p. 33., not of Aublet. 



Derivation. Frederick Pursh first characterised the only known species in his Flora Americte Sep- 

 tentrionalis, and named it Tigilrea tridentita. The generic name, however, having been preoccu- 

 pied by Aublet, De CandoUe has named the present genus after Pursh himself. 



3fe 1. P. tridentaVa Dec. The 3-toothed-/<'«zW Purshia. 



Identification. Dec. in Lin. Trans., 12. p. 157. ; Prod., 2. p. 541. 



Synonyme. Tigarea tridentJlta P/i. Fl. Amer. Sept., 1. p. 33. t. 15., not of Aublet. 



Engravings. Ph. FL Am. Sept, t. 15. ; Bot Reg., t 1446. ; and our figs. 424, 425. 



Description, Sfc. A spreading subdecumbent shrub, scarcely exceeding 2 ft. 

 in height, with numerous branches, small whitish leaves, and rather many 

 424 small yellow flowers, which begin to 



expand about the middle of May, 



and thence continue, successively, 



into June. The leaves are grouped, 



wedge-shaped, and ending in 2 — 3 



teeth that are large for the size of 



the leaf, villose above, but covered 



beneath with a white tomentum. 



Buds scaly. Stipules none, or mi- 

 nute. {Dec. Prod., ii. p. 541., and 



amplified from observation.) A native of North America, 

 in pastures by the river Columbia. It was almost the only shrub to be seen 

 through an immense tract of barren sandy soil, from the head source of 

 the Missouri, to the Falls on the Columbia, and from 38° to 48° n. lat. 

 {Douglas, in Hook. Bor. Amer.) It was introduced in 1826. There are 

 plants of this species, in the garden of the London Horticultural Society, 

 about 2 ft. or 3 ft. high, which flower freely every year. They require a dry 

 light soil; and cuttings of the young wood will root in sand under a hand- 

 glass. Plants, in the London nurseries, not being much asked for, are 2s. Qd. 

 each. 



3 c 2 



425 



