An Encyclopedia of Horticulture. 



257 



Pyrethrum. — eontinwed. 

 bonier, anil in the achenes being angular but not winged " 

 (LiniUey and Moore). All the species here described 

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

 Chrysantlieinuiii. 



"hm'^y. 



>..-' 



Fig. 331. Flgwer-he.ids of Pvretiirum frutescens. 



P. achlUesefollum (Achillea-leaved).* jl.-hmdx Rnlden-yellow, 

 ahnost f;li.ilml:a-, few, on lung stalks, and ilis|i,,si.-cl in loose 

 corymlis ; inner scales of the involuore round, \\ liite, and trans- 

 parent at the top. Summer. I. pinnatifld, with pinnate segiuents, 

 covered with silky down when young, and pubescent when full 

 Ri'own. h. 2ft. Caucasus, 1823. A variety known as jmbcsccns 

 has numerous heads arranged in broad corymbs. 



P. corsrmbosum (corymbose).* fi. -heads white ; peduncles corym- 

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

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



Pyrethrum. — continued. 



the lobes acute and argutely serrated. Stem erect, angular, 

 branched at apex. h. 1ft. Europe, Ac, 1596. (J. F. A. 379, 

 under name of Chyyaa/ithetnum curtfmboaum,) 



P. frutescens (shrubby), jl. -heads with white ray florets, h. 3ft. 

 ('anary Islanils, 1699." From this species a great number of 

 varieties liuve sprung. See Fig. 331. See also Chrysanthemum 

 frutescens. 



P. lacustre Uake-loving). Ji. -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, h. 2ft. to 25ft. Portugal. 



P. parthenlfoUum aurcum (Rolden 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 be picked oft whenever 

 they ajjpeiir. 



p. Parthenium (Parthenium). Common Pellitory or Feverfew- 

 fi.-heads with a yellow disk ami white ray, disposed in a corym- 

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

 pinnatifld and toothed. Stem erect, h. 2ft. Europe (Britain). 

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

 under natue of Matricaria I'artheuiuut ; Sy. En. B. 715, under 

 name of Chri/santheuiuia Parthenium). The double-flowered 

 form is largely gi'owu, and is very handsome. 



Fi«. 332. Upi'ER PoRTioss OF Plant ok Pvuetiirim roskum. 

 Vol III. 



Fig. 333. Pvrethriim roseum flore-pleno. 



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

 leucant he I II u III, anliiiuy: ray florets rose-coloured ; disk yellow. 

 I. pinnatifld, with decurrent, lanceolate segments of a vivid gieen 

 colour, h. 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 Chrjis- 

 anthemuin eoeciiieum.) 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. Tchihatchewli (Tchihatcheft's).* fi.-heads with a yellowish 

 disk an. I a jiure white ray, small, solitary, on axillary stalks 3in. 

 to 6iu. long. Early summer. I. bipinnatifid, glabr.ais, dark 

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

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

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

 banks, and under trees where grass will not giow. 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 3in. apart. 



P. uliginosum (moisture-loving).* tireat Oxeye. jl. -heads with 

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

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

 toothed, about 4in. long, sessile. Stems stout, h. 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.) 



PTRGUS. A synonym of Ardisia. 



PYRIPORM. The same as Pear-shaped (which 

 see). 



P7ROIf A (a diminutive of Pijrus, the Pear-tree ; 

 so-called from some fancic<l resemblance in the foliage, 

 which is not obvious). Wintergreen. Ord. Ericareai. 

 A genus comprising about fourteen species of hardy, 



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