PEEl] 



Cije Crratfurj) al Watting. 



866 



long flattened seedless lower portion and 

 four-seeded above. [W. C] 



PERISTYLUS. According to Lindley 

 the species of orchids collected under this 

 genus, of which there are upwards of twen- 

 ty, have all the characters of Platanthera, 

 except that, instead of a galeate perianth 

 and long slender spur, their calyx is always 

 campanulate, and the spur very short and 

 often pouch-like. Most of the species he- 

 long to the temperate regions of the north- 

 ern hemisphere ; but a few are found within 

 the tropics, principally in Ceylon, Java, and 

 theMascaren Islands. Nearly all have at 

 one time or other been referred to other 

 genera, such as Her minium and Habenaria ; 

 and the two British species, P. albidus and 

 P. viridis, are to be found under the latter 

 genus in many of our local floras. [A. S.] 



PERITHECIA. A word used to indicate 

 those kinds of cysts or capsules which con- 

 tain asci, and therefore not strictly appli- 

 cable to those which merely give rise to 

 sporophores producing naked spores. The 

 Messrs. Tulasne have proposed for these the 

 name of ' pyenidia,' and for the fruit that 

 of ' stylospores.' Perithecia are of various 

 colours, as yellow, blue, red, black, &c„ and 

 are mostly more or less decidedly cellular 

 in structure, their walls being of greater or 

 less density and thickness, and more or 

 less decidedly different from the substance 

 in which they are immersed when a stroma 

 is present. In consequence, it is some- 

 times impossible to distinguish them from 

 the stroma ; and for this reason, in Dothi- 

 dea the ascigerous cavities are called cells 

 and not perithecia, the only distinctive 

 mark of the genus. In some cases a third 

 kind of cyst occurs in Sphrerice and some 

 other genera, which contains naked bodies 

 supposed to have the function of pollen- 

 grains. In this case the cysts are called 

 ' spermagoma,' and the enclosed bodies 

 ' spermatia.' [M. J. B.] 



PERITROPAL. Directed horizontally as 

 regards the axis of a fruit. 



PERIWINKLE. Vinca. 



PERLEBIA. A Brazilian tree said to 

 be common in some parts of the province 

 of Minas Geraes, having the appearance of 

 a small-leaved Bauhinia, but differing from 

 that genus, according to Martius, in the 

 pod, which is divided into several cells, as 

 in some Cassias, by transverse partitions 

 between the seeds. It is only known as 

 yet from a very short notice in Martius's 

 Travels, and may possibly prove to be some 

 described species of Bauhinia. 



PERLIERE. (Fr.) Gnaphalium. 



PERMAYRUTTE. An Indian name for 

 the Malabar Catmint, Anisomeles malaba- 

 rica. 



PERNAMBUCO-WOOD. Ccesalpinia eclii- 

 nata. 



PERNETTIA, or PERNETTYA. A 

 genus of heathworts, distinguished by 

 the presence of ten glands alternating 

 with the stamens ; by the convex and 



slightly five-lobed stigma ; and by the five- 

 celled fruit, each cell with many seeds. 

 The species are small branched evergreen 

 shrubs, witli alternate leaves, and droop- 

 ing white flowers. They are found in Peru 

 and Mexico, and about the southern 

 extremity of South America. The name 

 was given in honour of Pernetty, a French 

 navigator. [G. D.] 



PAROLE. (Fr.) Centaurea Cyanus. 



PERONATE. Laid thickly over with a 

 woolly substance, becoming a sort of 

 meal. 



PERONOSPORA. A genus of naked- 

 spored moulds, separated from Botrytis by 

 Corda on very insufficient grounds, but in 

 later times proved by Caspary and others 

 to exhibit such characters as render its 

 separation imperative. The mycelium or 

 hyphasma (as it is often called) creeps 

 amongst the loose tissue of living leaves, 

 and rapidly causes its destruction. From 

 the mycelium, erect threads are given off, 

 and make their way into the surrounding 

 air through the stomates. These threads 

 are mostly inarticulate, and more or less 

 branched and often forked above, and 

 have at their tips large generally ovate 

 spores, Amongst the threads of the myce- 

 lium globose sacs are produced, containing 

 a single spore. This structure has, how- 

 ever, been observed in a few species only. 

 Peronosporce are most active agents in the 

 destruction of vegetables, and it is to the 

 ravages of P. infestans that the potato 

 murrain is due. This species differs from 

 all others in the curious swellings which 

 exist on the upper branches. [M. J. B.] 



PEROTIS. A genus of grasses belong- 

 ing to the tribe Agrostidece. The inflores- 

 cence is in nearly simple spikes ; spikelets 

 one-flowered ; glume two-valved, the valves 

 with bristles at the end ; pale one, nearly 

 as long as the calyx. There are about half 

 a dozen species, natives of the East Indies, 

 China, and New Holland. [D. MJ 



PERPIGNAN-WOOD. A name under 

 which the wood of Celtis australis is used 

 by the French. 



PERRETTE. (Fr.1 Citrus Limetta. 



PERROQUET. (Fr.) Alstriimeria psit- 

 tacina. 



PERROTTETIA. A genus of Celastracece, 

 consisting of unarmed shrubs, with alter- 

 nate ovate serrate leaves, and minute flow- 

 ers in slender axillary panicles. The calyx- 

 lobes and petals are five each, the ovary 

 is free and two-celled,with two erect ovules 

 in each cell, and the fruit a small, globular 

 berry. There are four species known, from 

 the mountains of New Grenada, Mexico, 

 and the Sandwich Islands. 



PERSEA. The Alligator Pear of tropical 

 America, and its allies, form a genus of Lau- 

 racece, characterised by their perfect flow- 

 ers having a more or less downy six-parted 

 calyx, which persists at the base of the 

 fruit but at length falls away, the segments 



