PETREA 



PETUNIA 



2503 



subjected to the usual condition of moisture and shade 

 required for other plants. When they are wanted to 

 grow in pots, keep shifting until they are in 8- or 10- 

 inch pots. The compost may be renewed in the spring. 

 (J. J. M. Farrell.; 



volftbilis, Jacq. PURPLE WREATH. Fig. 2878. 

 Twining: Ivs. 3-4 in. long, short-stalked, ovate, elliptic 

 or oblong, acuminate or obtuse, entire or wavy: fls. 

 blue, in terminal elongated racemes (7-8 in. long); 

 calyx with a tube one-fourth to one-half as long as the 

 pedicel, and in fr. one-third to one-fourth as long as the 

 narrow lobes; corolla included in the calvx. Cuba to 

 Brazil; a showy plant. B.M. 628. G.C. III. 39:24, 25; 

 4.5:252; 51:287. J.H. III. 54:390. G. 29:192. H.F. 

 8:50. F.E. 23:582. F.C. 3:108. Gn. 12:40. The pur- 

 ple wreath is one of the most distinct and beautiful 

 of tender climbers. The fls. are like a 5-pointed star 

 of lilac with a violet in the middle. The fls. begin to 

 open at the base of the raceme and the showy 5-pointed 

 star is the calyx, whose sepals are colored like petals. 

 The calyx spreads open while the corolla is still a round 

 bud in the middle, and it remains after the corolla has 

 fallen, so that the vine, at first glance, seems to bear 

 two kinds of fls. The blooms appear in March and 

 April. It does not bloom freely in small plants; it 

 probably has other drawbacks, for it has always been 

 a rare plant in Eu.. though enthusiastically com- 

 mended. Offered in S. Calif. The fls. seem to vary 

 considerably in color. WILHELM MILLER, 



L. H. B.j 



PETROCALLIS (Greek, rock beauty). Crudfers. 

 This genus has been commonly included in Draba but 

 differs from it in technical botanical characters as fol- 

 lows: silique oval with swollen reticulate valves having 

 1-2 seeds in a cell with the funiculum adnate to the 

 septum. One species in the Pyrenees, P. pyrenaica, 

 R. Br. Height 2-3 in.: Ivs. wedge-shaped, 3-lobed at 

 apex: fls. white at first, changing to rosy pink. May. 

 Mountains, S. Eu. B.M. 713. Also found under 

 Draba pyrenaica, page 1068; grown as a little rock-plant 

 in choice collections. 



PETROCOPTIS (Greek, equivalent to the Latin 

 Saxifraga, to break or deft the rock: rooting in the 

 clefts of rocks). Caryophyilace^e. Two or 3 perennials 

 from the Pyrenees, sometimes used in alpine- and rock- 

 gardening. Allied to Lychnis and sometimes united 

 with it, differing in imbricated rather than convolute 

 estivation and in bearded or woolly seeds. Perennials 

 of small size with uncut petals and a corolla-crown, 

 the Ivs. mostly tufted or in a rosette: st.-lvs. opposite. 

 P. pyrenaica, A. Br. (Lychnis pyrenaica, Berger). 

 Three to 4 in. high from a fusiform root: Ivs. glaucous- 

 green, spatulate, those on the st. cordate and sessile: 

 fls. pale flesh-color or rose-color, about ^in. across, in 

 forked clusters, the slender pedicels 1-fld.; petals shal- 

 lowlv notched at top, bearing 2 erect serrate scales. 

 B.M". 3269. Var. alba, Hort., is listed as a beautiful and 

 easily grown alpine, late blooming. P. Lagascae, Willk. 

 .(Lychnis Lagdscx, Hook. f.). Low and tufted, glabrous 

 and glaucous, 24 in. high: st. densely distichous, leafy 

 below : lowest Ivs. linear and obtuse, middle ones ovate- 

 lanceolate, subacute: fls. pale rose with white center, 

 about 2iin. across, with 2 white acute scales at base, 

 slightly notched at apex. B.M. 5746. A charming 

 P lant - L. H. B. 



PETR6PHYES: Monanthes. P. muraiis, Webb=Monanthes 

 . Hook, f., which equals M. atlantiea. 



PETROPHYTUM (petros, rock, and phyton, plant; 

 alluding to its habitat 1 !. Rosaces. A genus of 5 ces- 

 pitose undershrubs with prostrate branches in W. N. 

 Amer., allied to Spiraea, but differing in its follicles being 

 dehiscent on both sutures and in its habit : Ivs. crowded, 



spatulate or. oblanceolate, entire: fls. in terminal 

 racemes; sepals and petals 5; stamens 20; pistils 3-5, 

 hairy, style slender, glabrous except at the base: follicles 

 leathery, with few linear seeds. Only the following 

 species has been intro. into cult, and is offered bv several 

 European nurseries. It is perfectly hardy and grows 

 best in a rockery in a sunny and well-drained position 

 between rocks; it demands limestone soil. Prop, is by 

 division or by seeds treated like those of spirea, but the 

 young seedlings are particularly impatient of too much 

 moisture. P. caespitosa, Rydb. (Spiraea cxspitbsa, 

 Xutt. Eriogynia caespitosa, Wats. Luetkea csespitosa, 

 Kuntze). Densely cespitose, forming flat patches: Ivs. 

 oblanceolate, obtuse or mucronate, 1-ribbed, densely 

 silky, M-Kin- long: fls. small, white, in dense spikes 

 %~l% in. long on upright stalks 1-4 in. long; petals 

 spatulate, obtuse; stamens exserted. Julv, Aug. S. D. 

 and Mont, to Calif, and New Mex. M.D.G. 1907:85. 



ALFRED REHDER. 



PETROSELOTUM (Greek, rock-parsley}. Umbel- 

 liferse. About a half-dozen European chiefly biennial 

 herbs, one of which is cult, for its ornamental and edible 

 herbage. Closely allied to Carum and Apium, with the 

 former of which it is often united and from which it is 

 chiefly distinguished by the greenish yellow fls. and 

 broader incised If.-segms. Lvs. ternately pinnate- 

 compound, the segms. toothed and cut: fls. in com- 

 pound umbels with few parts to the involucre and 

 several or many parts to the involucels, the petals with 

 incurved points: fr. ovate and compressed, glabrous. 

 P. hortense, Hoffm. (P. satirum, Hoffm. Carum Petrose- 

 finum, Benth. & Hook. f.). PARSLEY (which see). 

 Erect, 1-3 ft.: Ivs. ternate-pinnate, the Ifts. ovate and 

 3-cleft (much cut in the "curled" garden varieties), the 

 upper ones narrower and nearly entire: fls. yellowish. 

 Old World. Much cult., and sometimes runs wild 

 about plantations. L H. B. 



PETTERIA (after Franz Fetter, a Dalmatian bota- 

 nist; died 1853). Legumindsx. One species, a shrub, 

 very similar in habit to Laburnum, but with the yellow 

 fls. in upright dense racemes, terminal on leafy branch- 

 lets. It is but rarely cult., since it is less showy in 

 bloom than Laburnum or many species of Cytisus. It 

 is hardy as far north as Mass., and requires the same 

 cult, as Laburnum, which see. If grafted, laburnum 

 is to be used as a stock. This monotypic genus 

 differs from Laburnum in its upright racemes, in the 

 tubular calyx, the wings and keel being at the base 

 adnate to the stamens, and in the sessile ovary. It is 

 said to possess the same poisonous properties as that 

 genus. 



ramentacea, Presl (Cytisus fragrans, Welden, not 

 Lam. C. Weldenii, Vis. C. ramantaceus, Sieb. Laburnum 

 ramentaceum, Koch. L. Weldenii, Lavallee). Upright, 

 to 6 ft. : Ivs. 3-foliolate, almost glabrous or sparingly 

 pubescent when young, on about l-in.-long stalks; Ifts. 

 cuneate, obovate to oblong, usually obtuse, %-2 in. 

 long: fls. fragrant, very short-pedicelled, in l-3-in.-long 

 dense racemes; calyx 3-lobed, silky; keel silky: pod lin- 

 ear-oblong, sparingly silky, to 1J^ in. long. May, June. 

 Dalmatia, Istria. B'.R. 29:40. ALFRED REHDER. 



PETUNIA (Petun, South American aboriginal name, 

 said to have been applied to tobacco). Solanacex. 

 PETUNIA. Small herbs, grown for their showy bloom as 

 garden annuals. 



Annual or perennial, branching, viscid-pubescent, of 

 weak or straggling growth : Ivs. alternate, or opposite 

 above, soft, entire: fls. white or purple, or in shades of 

 reddish, on solitary, terminal or axillary peduncles; 

 calyx deeply 5-parted, the lobes narrow or often foli- 

 aceous; corolla funnelform or salverform, the tube long 

 and nearly or quite straight and sitting loosely in the 

 calyx, the limb broad and normally 5-lobed, unequal or 



