the large group of Weevils (Curculionidae). — 
AN ENCYCLOPAEDIA 
OF HORTICULTURE. 149 
PISONIA (named in honour of Willem Piso, of Amster- 
dam, an eminent physician and writer on natural history, 
who died in 1648). Syns. Calpidia, Ceodes, Columella, 
Pallavia, and Torrubia. ORD. Nyctaginee. A genus con- 
sisting of about sixty species of unarmed or rarely spiny, 
glabrous or pubescent, erect or rarely sub-scandent, stove 
or greenhouse trees and shrubs, mostly natives of tro- 
pical America; a few are found in Asia and the Pacific 
Islands, and six in the Mascarene Islands. Flowers 
pink, greenish, or yellow, small, disposed in paniculate, 
sub-sessile, or pedunculate cymes, two or three-bracteo- 
late; male perianth tubular- or infundibular-campanu- 
late, female large and oblong; limb of five short teeth 
or lobes. Fruit a small or rather large, elongated 
utricle. Leaves opposite or scattered, sessile or petio- 
late, oblong, ovate, or lanceolate, entire. A few of the 
species are known to cultivation, but they have very 
little to recommend them to gardeners. Those described 
below thrive in well-drained loam. Propagation may 
be easily effected by cuttings, inserted in similar soil. 
P. aculeata (prickly). West Indian Cockspur. jl. greenish, 
in small, dense cymes or globular — March. fr. in loose 
cymes, often forming large panicles, opposite or here and 
there alternate, petiolate, ovate, often Seon or rarely oblong 
or lanceolate, obtuse, entire, rarely exceeding 3in., and often 
less than 2in. long. h. 10ft. Tropics, 1806. A tall, woody, green- 
house climbing shrub, often armed with stout, recurved, 
axillary prickles. 
P. grandis (grand). A synonym of P. inermis. 
P. inermis (unarmed). fl. greenish, collected in small cymes, 
forming a terminal, rather corymbose panicle, usually shortly 
pedunculate. March. l 
or almost obtuse, rounded or narrowed at base, often 6in. to 8in. 
— 10ft. Australia, 1806. A small, greenhouse tree. SYN. 
grandis. 
— obtusata (obtuse eenish, shortly pedicellate ; cymes 
1 terminal. dint Probe borate or obo bovate-oblong, rounded 
2 j small | genus of beetles, included under 
The species 
are few, and are much alike in size and appearance. All 
feed, both as larve and as perfect insects, on coniferous 
trees. An account of their ravages is given under the 
heading of Pine Weevils. 
PISTACHIO OR PISTACIA NUT-TREE. See 
Pistacia vera. 
PISTACIA (from Pistake, the old Greek name, used 
by Theophrastus, and that from the Persian Pista). 
Syn. Terebinthus. ORD. Anacardiacee. A com- 
prising half-a-dozen species of hardy, small- -growing 
trees, five of which are natives of the Mediterranean 
D ie 
region, from Western Asia to the Canary Islands, and 
the sixth Mexican. Flowers small, apetalous, dicecious, 
disposed in axillary panicles or racemes; pedicels 
bracteate at base. Fruit a one-seeded, dry drupe. 
Leawes alternate, perennial or deciduous, trifoliolate or 
pari- or impari-pinnate. P. Lentiscus, P. Terebinthus, 
and P. vera, are trees of great economic value. The 
species in cultivation thrive best in a rich, deep, sandy 
loam, and against a wall. Propagated by layers, or by 
_ cuttings. 
P. atlantica —— fi. in loose, panicled racemes ; anthers 
ithe ba 1, te i-pinnate; leaflets usually nine, tapering 
base. k Canaries, 1790. Evergreen. 
i 1 —— Mastich-tree. reen, 
sh issue from the sides of re branches.“ ‘Spring. —— 
}; leaflets eight, a agg 
South Europe, 1663. Eve This —— Fielda i the 
drug known as “mastich.” M. PL 63 L 63.) The AY a angusti- 
Jolia has almost linear aaien in tas wen known 
as Chia they are ovate, 
P. Terebinthus — 
disposed in — com 
stigmas crimson. 
mtine-tree. A. greenish, 
; anthers dull — 
June. l —— 
lanceolate, rounded at the — and mucronate at the 
h. 30ft. South Europe, 
petiolate, ovate or oblong, acuminate — 
rowed into a channelled petiole. All the species descri b 
Pistacia—continued. 
P. vera (true). Pistachio Nut-tree. fl. brownish-green. April. 
fr. panicled, about lin. long, o ovate, with an oblique point, reddish. 
l. pinnate ; "leaflets ovate, aprig a little to the base, rather 
mucronate ‘at the apex. h.20ft. Syria, 1770. Deciduous, 
PISTIA (probably from. pistos, watery ; in reference 
to the habitat). Syns. Apiospermum, Limnonesis, Zara. 
ORD. Aroidee (Aracee). . A monotypic genus. The 
species is an ornamental, stove aquatic, requiring plenty 
of heat. It increases rapidly, and often completely coats 
tropical ponds and water-tanks with verdure, keeping 
the water beneath fresh and cool. The plant floats on 
the water, and sends down many long, feathery roots, 
Each plant sends out several runners, and upon the ends 
of these other similar plants are formed, which again 
send out runners. 
P. Stratiotes (Stratiotes).* Tropical Dockweed ; Water Lettuce. 
fl. greenish, very small, borne in little spathes at the end of the 
leaves, each spathe containing one male and one female flower 
attached to an adnate spadix. 1, Mig di , slightly concave, 
notched or round — 2in. to bin. long, o; — — — 
green, covered with fine hairs. Tropics, 1843. (B. M. $ 
F. d. 8. ag! Pree oa Fulig 
PISTIL. The female organ in flowers; it consists of 
ovary, style, stigma, and ovules, or at least of ovary 
and stigma. 
PISTORINIA. [Included under Cotyledon (which 
see). 
PISUM (the old Latin name, — by Virgil, akin to 
the Greek Pison). Pea. ORD. Leguminose. A genus 
comprising only a couple of species of diffuse or climb- 
ing, hardy, annual herbs, one of which is much cultivated, 
and is here and there naturalised, in the Mediterranean 
region and in Western Asia, and the other is a native 
of the Taurian Mountains. Flowers purple, rose, or white, 
showy; peduncles axillary, elongated, solitary or a few 
racemose; calyx lobes sub-equal, or the two upper ones 
- broader; standard broadly obovate or sub-orbicular ; wings 
falcate-oblong, longer than the keel. Pods compressed, 
obliquely acute, bivalved. Leaves pinnate; common petiole 
terminating in a bristle or tendril ; leaflets one to three- 
jugate. P. elatius requires similar treatment to Lathy- 
rus (which see). For culture, &c., of P. sativum, see Pea. 
P. elatius (tall). fl. pale red, with the lamina of the wings dark 
purple ; peduncles ae flowered, erect, longer than the leaves. 
June to September. , petioles terete, bearing six lanceolate- 
oblong leaflets ; ——— rounded and crena below. Stems 
erect. Iberia, 1620. Climber. — 
tioles terete, bearing three 
pairs of ovate, entire, — — with undulated margins, 
A j 
ma Sea A — 
which there are several varieties, including arvense, h = 
(Dwarf Pea), macrocarpum, quadratum, saccharatum (Sugar Pea), 
and wmbellatum (Crown Pea). ; 
PITCAIRNIA (named after W. Pitcairn, a physician, 
of London). Syn. Hepetis. Including Neumannia and 
Pepinia. ORD. Bromeliacee. A genus com about 
seventy species of stove perennial herbs, rarely shrubs, 
generally stemless, with the leaves in a dense rosette; 
they are all natives of tropical America. Flowers red, 
yellow, or whitish; calyx with a short, obconical tube, 
adnate to the base of the ovary, and three large, lan- 
ceolate segments; corolla of three lingulate, unguiculate 
petals, one and a-half to three times the length of the 
sepals, usually with two minute scales at the base; 
stamens six; peduncle leafy, the proper leaves passing _ 
gradually into bracts; inflorescence generally a simple 
or panicled raceme, rarely a head or sub-spicate raceme. — — 
Leaves linear or ensiform, rarely oblong, lepidote on the 
back, or green and naked on both surfaces, often prickle- 
margined, especially towards the base, sessile or na 
below are herbaceous perennials, except where | 
stated. For culture, see Æchmea and Bi 
The following enumeration of species is based 
