78 



THE DICTIONARY OF GARDENING, 



Peridermium continued. 



on trees under twenty years old. The pcridia are about 

 tin. or iin. long, and in. high, and are usually flattened 

 on the sides. They are generally crowded (see Figs. 86 

 and 87), and may occur on the same branch for two or 

 more years in succession ; but they ultimately kill the 

 branches. The Fungus is also found on the needles, in a 

 form called P. acicolum. The peridia are much smaller in 

 this form, and are more cylindrical, and stand in a row 

 along the needles ; but the latter are not so severely 

 injured as the branches. The growth of the mycelium in 



PIG. 86. STEM OF YOUNG PINE ATTACKED BY PERTDEHMIUM PINI. 



the branches causes the conversion of the starch and 

 other food stores in the cells into turpentine and resins, 

 which soak into all the tissues, and at last often appear 

 on the surface of the branches. Investigations by Wolff 

 and others have, of late years, led to the belief that 

 this Fungus is only a stage in the life-cycle of another, 

 named Coleosporium Senecionis, which has long been 

 known as a widespread and abundant parasite on the 

 leaves and stems of Groundsels (Senecio vulyaris and 

 S. viscosus) and of Ragwort (8. Jacobean). The Coleo- 

 sporium forms yellow or orange spots, crowded into 



FIG. 87. BARK OF PINUS SYLVESTIUS INVADED nv PEUTDERMIUM 

 PINI a, a, Young Peridia ; b, Peridium opened. 



irregular patches, or in concentric rings, or scattered 

 over the leaves. These spots are composed of masses 

 of small, orange-yellow spores, covered with fine warts, 

 and nearly round, or cylindrical or clavate in form. Ex- 

 periments in growing the Fir-parasite from these spores 

 so often fail, that further evidence on their connection 

 is desirable. Almost the only available remedy is to cut 

 off and burn all parts of the trees that show the 

 disease, and to keep the neighbourhood of the trees 

 as clear as possible of species of Senecio. 



PERIGONE. The same as Perianth (which see). 



PERIGYNOUS. Petals are said to be Perigynous 

 when the disk bearing them is quite free from the 

 ovary, but is more or less combined with the base of 

 the calyx tube. 



PERILLA (said to be the Indian name). STN. 

 Dentidia. OED. Labiates. A genus consisting of only 

 two or three species of half-hardy, annual herbs, natives 

 of the mountains of India and China. Flowers small, 

 pedicellate; calyx campanulate, five-fid, nodding after 

 florescence, and bilabiate; corolla tube included, limb 

 shortly five-fid ; whorls two-flowered, secund, disposed in 

 axillary or paniculate racemes; bracts short, or rarely 

 exceeding the calyx. Leaves usually violet or greenish. 

 The plants thrive in any light, loamy soil, and may be 

 increased by seeds. P. ocimoides crispa is sometimes 

 employed in summer bedding. It requires, practically, 

 little attention beyond pinching out the points occa- 

 sionally, because of its very dark and distinct foliage. 

 Seeds, should be sown in pans or boxes, about the 

 middle of March, and placed in a gentle heat. After 

 being gradually hardened off, the seedlings may be 

 placed in the open border about the end of May. A 

 few well-grown examples of this plant will be found 

 very useful in sub-tropical gardening. 



P. hetcromorpha (variable - formed). A synonym of 

 P. ocimoides. 



P. nankinensis (Nankin). A synonym of P. ocimoides crispa. 



P. ocimoides (Ocimum-like). Jl. white, numerous; corolla 

 minute ; racemes shorter than the leaves. July and August. 

 I. broadly ovate, 2in. to 4in. long, acuminate, cunt-ate at base or 

 narrowed into the rather long petioles, sub-rugose, deeply crenate- 

 serrate. Stem erect, 1ft. to 3ft. high, thick, tirm, obtusely tetra- 

 gonal, sulcate. India, China, &c., 1770. SVN. P. Iteteromorpha. 

 (B. M. 2395.) 



P. o. crispa (curled).* A garden form, having dark bronzy-purple 

 leaves, with the margins crisped and iimbriated. " China. 

 SYN. P. nankinetmis. 



PERIIiOMIA (from peri, around, and loma, a fringe ; 

 alluding to the membranous-winged nutlets). ORD. 

 Labiatae. A genus comprising about eight species of 

 greenhouse or half-hardy, loosely or densely branched, 

 sometimes sub-scandent, leafy shrubs, natives of the 

 mountains of South America, extending from Chili or 

 Bolivia to Mexico. Flowers scarlet ; calyx campanulate, 

 slightly gibbous at back, bilabiate, with short, entire lips ; 

 corolla frequently pubescent or villous, with an exserted, 

 incurved tube, and a short, bilabiate limb ; whorls two- 

 flowered, secund, axillary, or the uppermost ones sub- 

 racemose. Nutlets erect, triquetrous or compressed at 

 back. Leaves dentate ; floral ones conformed, or the upper- 

 most ones reduced to bracts. The undermentioned species 

 the only one introduced is a very pretty half-hardy 

 evergreen shrub, thriving best in a sandy-peat soil. It 

 may be propagated, in April, by cuttings of young shoots, 

 inserted in sand, under a glass. 



P. scutcllaroidcs (skull-cap-like). fl. over Jin. long, forming an 

 elongated raceme, 6in. to 12in. long. August. I. ovate, crenated, 

 roundly truncate at the base, iin. to liin. long. h. 3ft. Peru, 

 1829. (B. 11. 1394, under name of P. ucimoides.) 



PERJPHANES. A synonym of Hessea (which see). 



FERIPHRAGMOS. A synonym of Cantua (which 

 see). 



PERIPLOCA (from peri, around, and ploke, a 

 twining ; in reference to the intertwining habit of some 

 species). OED. Asclepiadece. A genus comprising twelve 

 species of glabrous shrubs, sometimes twining and leafy, 

 sometimes erect, rigid, and aphyllous, inhabiting Southern 

 Europe, temperate Asia, and tropical and sub-tropical 

 Africa. Flowers often brownish or blackish within, 

 greenish outside, in loose cymes. Le&ves opposite, 

 glabrous. The undermentioned species is a very desir- 

 able plant for covering an arbour or wall, which it does 

 very rapidly. Any moderately good garden soil suits 

 it. Propagated by layers or cuttings, inserted under a 

 glass, during summer and autnmn. 



