AN ENCYCLOPAEDIA OF HORTICULTURE. 



257 



Pyrethrum continued. 



border, and in the achenes being angular but not winged " 

 (Lindley and Moore). All the species here described 

 are hardy, herbaceous perennials. For culture, &c., see 

 Chrysanthemum. 



FIG. 331. FLOWER-HEADS OF PYRETHRUM FRUTESCENS. 



P. achillesefolium (Achillea-leaved).* fl.-heads golden-yellow, 

 almost globular, few, on long stalks, and disposed in loose 

 corymbs ; inner scales of the involucre round, white, and trans- 

 parent at the top. Summer. 1. pinnatifld, with pinnate segments, 

 covered with silky down when young, and pubescent when full 

 grown, h. 2ft. Caucasus, 1823. A variety known as pubescent 

 has numerous heads arranged in broad corymbs. 



P. corymbosum (corymbose).* fl.-heads white ; peduncles corym- 

 bose ; involucral scales ovate-lanceolate, with fuscous, scarious 

 margins. July. I. pinnatisect ; segments lanceolate, pinnatifld, 



Pyrethrum continued. 



the lobes acute and argutely serrated. Stem erect, angular 

 branched at apex. A. 1ft Europe, &c., 1596. (J. F. A. 379* 

 under name of Chrysanthemum corymbosum.) 



P. frutescens (shrubby), fl.-heads with white ray florets. A. 3ft 

 Canary Islands, 1699. From this species a great number of 

 varieties have sprung. See Fig. 331. See oiso Chrysanthemum 

 frutescens. 



P. lacustre (lake-loving), fl.-heads pure white, with a yellow 

 centre, about 2in. across, solitary, terminal and axillary. Late 

 summer. I. alternate, numerous, sessile, ovate-lanceolate, 

 coarsely and irregularly toothed. A. 2ft to 2Jft. Portugal. 



P. parthenifolium aureum (golden Parthenium - leaved).* 

 Golden Feather. A free-growing and well-known, hardy plant 

 extensively used for carpet beds and edgings. Seeds should 

 be sown, in a gentle heat, during March. The seedlings grow 

 very rapidly, and will be ready for planting out in May or 

 early in June. The flower-buds must he picked off whenever 

 they appear. 



P. Parthenium (Parthenium). Common Pellitory or Feverfew. 

 fl. -heads with a yellow disk and white ray, disposed in a corym- 

 bose panicle. June. I. stalked, compound, flat ; leaflets ovate, 

 pinnalitid and toothed. Stem erect. A. 2ft. Europe (Britain). 

 The whole plant has a strong and bitter smell. (F. D. 674, 

 under name of Matricaria Parthenium ; Sy. En. B. 715. under 

 name of Chrysanthemum Parthenium). The double-flowered 

 form is largely grown, and is very handsome. 



FIG. 332. UPPER PORTIONS OF PLANT OF PYRETHRUM ROSEUM. 

 Vol. III. 



FIG. 333. PYRF.TTTRUM ROSEUM FI.ORE-PI,ENO. 



P. roseum (rosy).* fl.-heads larger than those of Chrysanthemum 

 leucanthemum, solitary ; ray florets rose-coloured ; disk yellow. 

 1. pinnatitul, with decurrent, lanceolate segments of a vivid green 

 colour. A. 1ft. to 2ft. Orient. This species, with one or two 

 others, is important from an economic point of view, as it is 

 largely used in the manufacture of "insect powders." See 

 Fig. 332. (B. R. 1084; B. M. 1080, under name of Chrys- 

 anthemum coccineum.) A large number of varieties, varying 

 much in size and colour of flower-heads, are now grown ; there 

 is too, a large series of double forms, one of which is repre- 

 sented in Fig. 333. 



P Tchlhatchewli (TchihatchefFs).* fl.-heads with a yellowish 

 disk and a pure white ray, small, solitary, on axillary stalks 3in. 

 to oin. long. Early summer. I. bipinnatifld, glabrous, dark 

 green, toothed at the base of the petiole. Stems very numerous, 

 rooting. A. 2ft. Asia Minor, 1869. A handsome species, form- 

 ing a dense tuft. It thrives remarkably well on slopes, dry 

 banks, and under trees where grass will not grow. The seeds, 

 by which it is mostly increased, should be sown in pots or 

 pans, and the seedlings, when large enough, transplanted to 

 their permanent quarters at about 3m. apart. 

 . uliginosum (moisture-loving).* Great Oxeye. fl.-heads with 

 a yellow disk and a white ray, over 2in. across, on slender and 

 gracefully-bending stalks. August. I. smooth, lanceolate, sharply 

 toothed, about 4in. long, sessile. Stems stout. A. 5ft. Eastern 

 Europe, 1816. A very bold and strong-growing species, having a 

 handsome and distinct appearance when covered with a pro- 

 fusion of its blossoms. It is perfectly hardy, and prefers a 

 rather sheltered situation. (B. M. 2706.) . 

 PYRGUS. A synonym of Ardisia. 

 PYRIFORM. The same as Pear-shaped (which 



see). 



PYROLA (a diminutive of Pyrus, the Pear-tree; 



so-called from some fancied resemblance in the foliage, 



which is not obvious). Wintergreen. ORD. Ericaceae. 



A genus comprising about fourteen species of hardy, 



2L 



p. 



