522 



PB ACTIO AL GUIDE TO GABDEN PLANTS 



BIDBNS 



fimd). — This is probably the jjlant first 

 introduced. The typical species has scar- 

 let or red ray florets and a yeUow disc ; 

 but there is great variation in the colour, 

 and this character seems to have de- 

 scended in a remarkable degree to the 

 garden Dahlia in which almost every 

 shade except blue is to be found. 

 Culture dc. as above. 



D. Zimapani (Cosmos dmersifolms). 

 Black Dahlia. — A tuberous-rooted 

 Mexican perennial, 12-18 in. high, with 

 a compact bushy habit, and deep green 

 leaves, cut into 5-7 ovate entire or slightly 

 toothed lobes. The deep violet or almost 

 blackish-purple flowers appear from July 

 to October, and are borne singly on long 

 stalks, well above the foliage. The 

 variety atropurpurea is much deeper in 

 colour than the type. 



Culture lie. as above. 



THELESPERMA.— A small genus 

 of smooth herbs or shrubs with opposite 

 leaves (or the upper ones alternate), 

 linear, thread-like, and once or twice 

 pinnately parted. 



T. filifolium. — A pretty bushy plant 

 about 2 ft. high, native of Texas, with 

 bright green finely divided leaves, and 

 large orange-yellow flower-heads produced 

 in summer, with a conspicuous purple- 

 brown blotch at the base of the broadly 

 obovate ray florets. The plant known as 

 Cosmidmim hurridgeanum is a hybrid 

 between this species and Coreopsis tinc- 

 toria, and is intermediate between the 

 two species. 



Culture and Propagation. — These 

 annuals flourish in light sandy soil, and 

 may be raised from seeds sown in gentle 

 heat in March or in the open border in 

 April as recommended for Cosmos 

 bipinnatus below. Seeds may also be 

 sown in cold frames in autumn, and the 

 seedlings transferred to the open border 

 the following spring, when danger from 

 frost is past. 



COSMOS. — Annuals and perennials 

 with pinnate leaves and solitary flower- 

 heads. Receptacle with linear acute co- 

 loured bracteoles as long as or longer than 

 the florets. Achenes angular, crowned 

 with 3-4 rigid bristles. 



Culture and Propagation. — These 

 plants are easily raised from seeds sown 

 in gentle heat in early spring, and pricked 

 out and treated like other tender annuals, 



as described at p. 78 of this work. The 

 roots of the perennials must be protected 

 in winter, and in spring the young shoots 

 can be taken off as cuttings. As, however, 

 these are rarely to be met with in cultiva- 

 tion, even in botardc gardens, the genus is 

 practically at present confined to C. bipin- 

 natus. A rich moist and sandy soil and 

 warm positions suit the plants best. To 

 keep up a succession seeds may also be 

 sown in the open border in April, but 

 they will rarely produce flowers save in 

 exceptionally favourable seasons. 



C. bipinnatus. — A beautiful Mexican 

 annual about 3 ft. or more high, with 

 finely out pinnate leaves. Flowers late 

 in summer, bright rose or purple, 2^3 in. 

 across, with a yellow centre, and borne on 

 rather short aiollary and terminal stalks. 



Culture dc, as above. This species is 

 not remarkable for its free flowering, but 

 owing to its graceful and finely divided 

 leaves it looks very ornamental when 

 grown in bold masses in the flower 

 border. 



BIDENS (Bur Maeigold;. — A rather 

 large genus of annual or perennial, some- 

 times climbing, smooth or hairy plants with 

 opposite leaves, toothed, incised, or once, 

 twice, or thrice ternately or pinnately 

 dissected. Flower-heads vrith white or 

 yellow spreading strap-shaped ray-florets 

 entire or slightly toothed. Involucre bell- 

 shaped or hemispherical. Receptacle flat, 

 or slightly convex. 



B. WarscevTiczi. — An elegant bushy 

 Mexican species about 18 in. high, with 

 leaves much cut into Unear segments. 

 The flower-heads which appear from July 

 to October very much resemble those of a 

 Coreopsis ; they are bright orange-yeUow, 

 and have obovate strap -shaped ray florets 

 surrounding a yellow disc. 



Culture and Propagation. — Although 

 about 100 species have been described 

 there are very few plants belonging to this 

 genus of sufficient value to merit a place 

 in the flower garden. The species de- 

 scribed above, although really a perennial 

 in its native comitry, is best treated as an 

 annual in om- climate. It will flourish in 

 ordinary good and well-drained garden 

 soil, and when grown in masses looks very 

 effective. Seeds may be sown in autumn 

 in cold frames, and the seedlings protected 

 under glass until May ; or they may be 

 sown in gentle heat in March, and the 

 seedlings transferred to the open in May. 



