905 



Clje £r?agurj) ai 33otanp. 



[pled- 



or bearded filaments and long narrow subu- 

 late curved anthers, opening by single 

 pores, baring tbe connective prolonged at 

 the base, and furnished with a couple of 

 knobs at its junction with the filament ; 

 and a five-celled hairy-topped ovary bear- 

 ing a slender curved style. Several species 

 are grown in hothouses in this country on 

 account of their beautiful large showy 

 flowers. [A. S.] 



PLEURACH37E. A genus of cypera- 

 ceous plants, belonging to the tribe Scirpece. 

 P. secunda, the only species, is now re- 

 ferred to Ficinia by Steudel. [D. 31.] 



PLEPRAXDRA. A genus of Dilleniacea?, 

 usually distinguished from Hibbertia by 

 the stamens being all inserted on one side 

 of the ovaries; but as the relative arrange- 

 ment of the stamens and ovaries in these 

 genera and their immediate allies has now 

 been found to be of a purely artificial cha- 

 racter, separating species otherwise very 

 similar, Pleurandra has been reduced to 

 a section of Hibbertia. The species are all 

 Australian, low shrubs or much-branched 

 undershrubs, with yellow flowers. 



PLEEREXCHYMA. The woody tissue, 

 consisting of tough slender tubes, out of 

 which the woody parts are mainly formed. 



PLEURISY-ROOT. Asclepias tiiberosa. 



PLEUROCARPI. One of the great divi- 

 sions of true mosses, containing Hypnum 

 and other genera which bear their fruit 

 on the sides of the branches ; the base of 

 the peduncle, or rather the short portion 

 of the axis which supports it, being rough, 

 with a few leaves which differ generally 

 from the others, and are called perichEetial. 

 The distinction is not, however, absolute, 

 as acrocarpous and pleurocarpous species 

 may occur in the same genus. [31. J. B.] 



PLEURODISCOUS. Growing on the sides 

 of the disk. 



PLErROGYNE. A genus of Arctic and 

 mountain plants with herbaceous stems, 

 leafless flowerstalks, and blue flowers. Co- 

 rolla wheel-shaped, fringed at the throat ; 

 stamens five, inserted into the throat of 

 the corolla ; anthers not becoming twisted ; 

 ovary one-celled, the style wanting, and 

 the stigmas two, prolonged downwards 

 along the edges of the ovary valves ; fruit 

 capsular. The genus belongs to the Gen- 

 tianacece. The generic name expresses the 

 peculiarity of the stigma. [31. T. 31.] 



PLEUROGTRATE. A term employed 

 for those ferns whose spore-case has a ring 

 carried round the sides. 



PLEUROPETALTJ31. A genus of Ama- 

 ranthacece, from the Galapagos Islands. It 

 comprises an erect glabrous somewhat 

 shrubby plant, with alternate elliptical- 

 lanceolate veiny leaves, and terminal and 

 lateral racemes of flowers, each with three 

 bracts, and a five-leaved deciduous peri- 

 anth ; stamens eight, united into a cup at 

 the base, with subulate filaments, two- 

 celled anthers, and no staminodes; ovary 



one-celled, with numerous ovules; style 

 short, with four stigmas. This genus was 

 at first referred to Portulacacece, the bracts 

 being supposed to be sepals, and the sepals 

 petals. [J. T. S.j 



PLEUROPHORA. A genus of Lythracece, 

 consisting of annuals or undershrubs from 

 Chili. They have four-sided branches ; op- 

 posite oblong-lanceolate or linear entire 

 leaves, often sharp-pointed ; and terminal 

 flower-spikes with the bracts densely im- 

 bricated, each flower with bractlets, often 

 spinescent. Calyx tubular, ten or f ourteen- 

 toothed, the inner ones ovate, mucronate, 

 erect, or connivent— the outer spiny and 

 spreading ; petals five to seven ; stamens 

 generally as many as the petals; ovary sti- 

 pitate, unequal-sided and excentric, one- 

 celled, with few ovules. [J. T. S.] 



PLEUROPHYLLTTM. A genus of Com- 

 positce, of the tribe Asteroidece, consisting 

 of two species from the Auckland and 

 Campbell Islands in the Antarctic regions. 

 They are both tall erect herbs, densely 

 covered with a white or silvery shining 

 silky wool. The leaves are alternate, the 

 lower ones very large, and the flower-heads 

 large and handsome, with purple florets, 

 and growing in a close terminal raceme. 

 The involucral scales are numerous and 

 narrow, the outer florets radiating, the disk 

 ones tubular, the receptacle without chaff, 

 and the pappus consisting of numerous 

 stiff bristles. 



PLETJROTHALLIS. One of the most 

 extensive genera of orchids, comprising 

 nearly three hundred species, the whole of 

 which are confined to tropical America and 

 the West Indies. By various authors it 

 has been split up into a dozen smaller 

 genera, but these have all been reunited. 

 The species are epiphytes, and are very 

 variable in habit : the majority have erect 

 one-leaved stems, either nearly naked or 

 closely sheathed, rising from a creeping 

 rhizome ; but in one section the stems are 

 scarcely at all developed, and in another 

 they bear numerous alternating leaves. 

 Their flowers, which proceed from spathes 

 and are solitary or racemose, have the la- 

 teral sepals usually coherent and enlarged 

 at the base, the petals free, and the lip 

 articulate with the prolonged base of the 

 column, which is terete or thin-winged and 

 truncate, or has the anther-bed thin-edged, 

 and the lid-like anther either at the top 

 or a little towards the back. The pollen- 

 masses, of which there are two or rarely 

 four, are free, waxy, and obovate or pyri- 

 form. [A. SJ 



PLETTROTUS. A subgenus of Agaricus, 

 containing those white-spored species 

 which have an excentric or lateral stem. 

 In a few the stem is at length or from the 

 beginning obsolete, and the pileus is resu- 

 pinate ; while in other cases it is at first 

 cup-shaped, and the margin on one side at 

 length turns over. The subgenus contains 

 a few esculent species, as A. osfreaft«s,which 

 is so common in autumn on laburnums arid 

 other trees. A species is also raised on 



