84 
THE DICTIONARY OF GARDENING, 
Petalostemon—continued. 
these organs in this genus). Prairie Clover. ORD. 
Leguminose. A genus comprising about fourteen species 
of pretty, hardy or half-hardy herbs, usually perennial, 
gland-dotted, closely allied to Dalea; they are confined 
to the warmer parts of North America. Flowers rose- 
coloured, purplish-violet, or white; calyx teeth or lobes 
sub-equal; standard heart-shaped or oblong; heads or 
spikes terminal, or opposite the leaves, often peduncu- 
late, sub-sessile. Leaves impari-pinnate; leafiets small, 
entire, exstipellate ; stipules minute, setaceous. The 
best-known species in cultivation are P. candidus and 
P. violaceus; these thrive in a compost of sandy loam 
with a little peat or leaf mould. They may be increased 
by divisions, in spring. Both are hardy perennials. 
P. candidus (White).“ f., corolla white; heads oblong, when old 
peeing uly. b» leaflets seven to nine, lanceolate or linear- 
long. h. lft. 1811. 
P. violaceus (violet).* fl., corolla Ne 
ovate, or oblong-cylindrical when old. 
narrow. linear. t. 1811. (B. M. 17070 
.PETAMENES. A synonym of Antholyza. 
PETASITES (an old Greek name used by Dios- 
corides, from petasos, an umbrella; alluding to the 
size of the foliage). Including Nardosmia. ORD. Com- 
posite. A genus comprising about a dozen species of 
hardy, more or less white-tomentose or woolly herbs, 
with perennial rhizomes or stems, natives of Europe, 
Asia, and North America. Flower-heads purple or white, 
rarely yellowish-white, heterogamous, mediocre, racemose 
or thyrsoid-paniculate at the tips of the scapes; invo- 
lucre campanulate or cylindrical; receptacle flat, naked. 
Leaves radical, often ample, cordate or reniform. Scapes 
or stems many-headed, with the leaves reduced to alter- 
nate scales, or rarely with the lower ones more evolute. 
Many of the species formerly included under Tussilago 
are now referred, by Bentham and Hooker, to this 
genus. All succeed in any ordinary soil, and may be 
increased by divisions. Some of the species are rather 
Re The following are among the best-known. 
333 (alpine). A orion of Homogyne alpina. 
Reals acute. Febna 9 white, 
1 a ebruary. 5 cordate at base, * 5 
Sree Ken at org * e 
Soni Wostees and there in 
ee heads globose- 
l, leaflets tive, 
rope . 5 
Britain). (G. C. n. s., 1479 SYN. Tussilago fragrans (B. M. 1388). 
P. frigida (frigid).* f.- hends white. April and May. l nded, 
somewhat Fentor, white-woolly 1 — A y and deeply 
five to seven-lobed, bin. to 10in. broad; lobes toothed and cut. 
h. 6in. Arctic regions, 1778. SYN. Tussilago 
P. niveus poy ji.-heads white, borne on simple pedicels. 
March. . broadly cordate, sub- tri toothed, slightly 
glabrous above, snowy-tomentose benen ; lobes divaricate, sub- 
acute. R. lft. Europe, 1713. 
„ vulgaris (common). Bog Rhubarb; Butter Bur. /.-heads 
borne in cylindric cles, Sin. 
to 10in. long, the female longest, 
1 after flowering; pedicels slender. March to May. 
l. 3in. to 3ft. in diameter, reniform or orbiewarly cordate, 
irregularly toothed, white or cobwebby beneath, and, when 
young, above also. Stems din. = Far high 
below. Europe (Britain), &. ybrida (i 
a nama the female stand os T. Petasites. (Sy. En. B. 
) 
PETASOSTYLIS. 
(which see). 
PETIOLAR. Borne on, or relating to, a petiole. 
PETIOLE. The footstalk of a leaf. 
PETIOLULE. The footstalk of a leaflet. 
PETIVERIA (named after James Petiver, F.R.S., 
1665-1718, an apothecary and distinguished botanist, 
of London). Syn. Mapa. ORD. Phytolaccaceæ. ` A 
monotypic genus (according to the authors of the 
“Genera Plantarum”). The species is an ornamental, 
slender, erect, glabrous or puberulous, dichotomously- 
branched : stove herb, 3 at base, with an alliaceous 
Included under Leianthus 
„ Stout, purplish . 
Petiveria—continued. 
smell. It thrives in a mixture of loam and peat, and 
may be increased by cuttings of the half-ripened wood, 
rooted in bottom heat. 
P. alliacea (Onion-like). Guinea-hen Weed. f. white, very 
shortly pedicellate, small, disposed in axillary and_ terminal 
racemes; perianth conical at base, with four spreading, per- 
sistent segments. June. fr. erect. l. alternate, petiolate, 
ovate, entire, membranous, Sin. to Ain. long (includin; the 
short petiole), lin. broad, attenuated at both ends, pellucid- 
dotted. Stem 2ft. to Skt. high. Mexico to Brazil. (L. B. C. 148.) 
P. a. octandra (eight-anthered). AH. with eight anthers and 
— — filaments. J. smaller, and stem shorter, than in the 
type. SYN. P. octandra. 
octandra (eight-anthered). 
octandra. 
PETRA (Linnzus dedicated this genus to Robert 
James, Lord Petre, a famous patron of botany, who 
died in 1742). ORD. Verbenacew. A genus comprising 
about a dozen species of beautiful, twining or arborescent, 
stove shrubs, natives of tropical America. Flowers 
violet, purple, or bluish, shortly pedicellate in the axils 
of the bracts; calyx lobes five, large, prettily coloured 
at the flowering season; corolla often intensely coloured, 
with a short tube, and an oblique, five-fid limb ; racemes 
elongated, terminal or in the upper axils. Leaves 
opposite, coriaceous. The species described below, which 
are, probably, all in cultivation, should be planted in 
good, rich mould, and kept in a strong heat. Propaga- 
tion may be readily effected by cuttings, inserted in 
light sandy soil, under a glass. P. volubilis is an ex- 
tremely handsome twiner. 
P. arborea (tree-like).* jl. blue, saturated with violet, disposed 
in copious, axillary or solitary, loose, pendulous racemes, 6in. 
long. June. J. oblong-lanceolate, obovate-obiong, or elliptic, 
narrowed at base, 4in. to Tin. long, 1lżin. to 24in. broad, sub- 
cordate, very shortly petioled, obtuse or retuse, and mucronate 
at 87 entire. R. 12ft. South America, 1823. Arboreous. 
(L. B. C. 1606, under name of P. meer t 
P. macrostachya (large-spiked 
elongated, 5 W 
Inte, ot shorter than the calyx 2 Sane, E vee, lanceo- 
te, to, Glorie or oval-elliptic, 4in. in. broad, shortly 
uminate at both ends, mucronate, — undulated. h. 20ft. 
South America. Twiner. P. M. B. iv. 99, under = of 
P. Stapeliæœ.) 
P. . ft. blue, shortly pedicellate, “disposed in 
Taek very shortly petioled, kite eee . se, and 
slig slightly rounded or at APOT: ogee entire, 2in 
ong, 
» wrinkled. 
A synonym of P. alliacea 
disposed in terminal, 
1755 to 2ft. long; 
retuse 
An. to lein. broad with reflex 
eee “he 618. to Phi S, l. Arber 3 
15 reous. 
* 
nate or obtuse, , entire, 
Ge. Gel 1783. (. M. 628.) 
PETR DUS, PETROSUS. Growing in rocky or 
stony places. 
PETROBIUM (from petros, a rock, and bio, to 
live; alluding to the habitation of the species). Syn. 
Lazmannia (of Forster). ORD. Composite. A mono- 
typic genus, the species being an ornamental, stove tree. 
It thrives in sandy loam, and may be increased by 
cuttings, which root readily in a similar soil. 
P. arboreum (tree. like). fl. leads yellow, dicecious, mediocre or 
rather small, disposed in corym panicl 
apices of the branches ; 3 3 — 
receptacle small, flat; achenes ee 
l. opposite, dentate. St. Helena, 1815. us, scabrous. June. 
e Included under Draba (which 
see). 
. A of Parinarium 
(which see). ANN 
A TROPO. Included under Lychnis (which 
see 
(which see). FFF. 
