Mexico, -with solitary flowers springing 

 from the axils of the ovate leaves. [G. D.] 



PERIXTEGER. Perfectly entire, or un- 

 divided. 



PERIPHERIC. Of or belonging to cir- 

 cumference. 



PERIPHERICO-TERMI> T AL. Belong- 

 ing to the circumference and apex of a 

 body : a term applied to stems which grow 

 both at the sides, augmenting their dia- 

 meter, and at the end, increasing their 

 length. 



PERIPHYLLIA. The hypogynous scales 

 of grasses. 



PERIPLOCA. A genus of Asclepiadacece, 

 inhabiting Southern Europe and tropical 

 rarts of Africa and Asia, and consisting of 

 about half a dozen twiners with ovate or 

 lanceolate leaves, or without any leaves 

 whatever. The flowers are arranged in 

 axillary cymes. The calyx is five-cleft, the 

 corolla rotate, and the fruit cylindrical and 

 smooth. The milk of P. grceca, a plant 

 common in the hedges of Southern Europe 

 and an inmate of our gardens, has been 

 employed in the East for poisoning wolves. 

 P. linearifolia is the Domaivo of Abyssinia. 

 The roots of P. vomitoria and P.'ciliata, 

 two little-known plants, are used as emetics 

 in Malabar; whilst a decoction of those 

 of P. viridiflora is employed in the same 

 country in ophthalmia, and the leaves for 

 swollen feet. For other useful species for- 

 merly classed with Periploca, see Hemi- 

 DESilUS and CAiTPTOCARPUS. [B. S.] 



PERIPTEROUS. Surrounded by a wing- 

 like expansion. 



PERISPERM. The skin of a seed. Also 

 the same as Albumen; thus perispermic is 

 furnished with albumen. 



PERI3PORANGIT7M. The indusium of 

 ferns when it surrounds the spore-cases or 

 sori. 



PERISPORIACEI. A natural order of 

 ; aseigerous Fungi characterised by the re- 

 ceptacles or perithecia being always closed 

 except in decay, and the nucleus never 

 softening into a gelatinous mass as in 

 Splicer iacei. The asci are generally large, 

 and sometimes solitary, and the sporidia 

 less frequently eight or indeed definite 

 than in neighbouring natural orders. The 

 curious mycelium has been noticed under 

 Erysiphe, now divided into several distinct 

 genera. Most of the species are true 

 parasites. See also Oiditjji. [M. J. B.] 



PERISPORE, PERISPORIUM. The hy- 

 pogynous seta? of sedges ; also the skin of 

 a spore. 



PERISTACHYUM. The glumes of 

 grasses. 



PERISTERIA. A genus of Orchidacece, I 

 named from the Greek word peristera, a ! 

 dove ; the original species, P. elata, being 

 known in Panama by the name-E7 Spirvbo 

 Santo, the Holy Ghost or Dove plant, in 

 consequence of the resemblance of the 



column of the flower to a dove hovering 

 with expanded wings, somewhat like the 

 conventional dove seen in artistic repre- 

 sentations of the Holy Ghost. Three other 

 species are known ; and several others have 

 been referred to the genus, but are now 

 placed in Acineta. All have fleshy pseudo- 

 bulbs, large plicate leaves, and radical 

 many-flowered scapes, with handsome near- 

 ly globular fleshy flowers. Their sepals are 

 concave and connate at the base, and the 

 petals resemble them, except that they are 

 a little smaller ; the lip has its lower half 

 continuous with the column and sagittate 

 at the base, and its upper half articulated 

 with the lower, undivided, and bent down 

 over the face of the column, which is short, 

 fleshy, and wingless , and the two pollen- 

 masses are furrowed, and sessile on a nar- 

 row gland. 



P. elata, the Dove plant, has striated 

 green pseudobulbs, as large as swan's eggs, 

 bearing three to five lanceolate strongly 

 ribbed and plicate leaves, sometimes up- 

 wards of a yard high and six inches across. 

 Its flower-stem rises from the base of the 

 pseudobulbs, and attains a height of from 

 four to six feet; its upper portion, for about 

 a third of its length, being occupied by a 

 spike of almost globose very sweet-scented 

 flowers, each about an inch and a half 

 across, and of a creamy-white, with little 

 lilac specks on the base of the lip. [A. S.] 



PERISTOME. When the lid breaks off 

 from the capsule of a moss, the edge of 

 I the cup is either naked, or is fringed with 

 one or more whorls of variously fashioned 

 teeth (the peristome), the outer of which is 

 continuous with the inner layer of cells 

 constituting the wall of the capsule, which 

 is separated from the spore-cyst by a cavity 

 traversed"by a few articulated threads— the 

 inner from the outer layer of cells in the 

 spore-cyst. The tissues of this latter gene- 

 rate the spores, leaving mostly a barren 

 cylinder in the centre, which is called the 

 columella. The teeth consist of one or j 

 more layers of cells, and are mostly trans- | 

 versely articulate, and often striate longi- 

 tudinally. They are usually definite in 

 number, being four or multiples of four. 

 They are variously combined, and often 

 have transverse processes like little pro- 

 jecting beams on the inner side, called ' tra- 

 beculag.' The teeth of the inner whorl may 

 be separate, or connected at the tips and 

 joined together by a common plicate mem- 

 brane. Other modifications occur, and 

 there is often a deciduous external ring of 

 cells at the line of dehiscence of the cap- 

 sule. [M. J. B.] 



PERISTROPHE. A genus of Acantliaceai 

 containing a score of species, natives of 

 India. They are herbs, with showy purple 

 flowers included inatwo-valved involucre, 

 and arranged in axillary and thin terminal 

 umbels. The calyx is five-cleft ; the corolla 

 two-lipped and resupinate, its lower lip 

 being uppermost and three-toothed, the 

 upper one entire or two-toothed ; there are 

 two stamens, with narrow two-celled an- 

 thers ; and the capsule is two-celled with a 



