PIGO] 



Kfyt &rca£urj? at 38ntang* 



— DOUX. A South European name for 

 the seed of Pinus Cembra and P. Pumilio. 

 — , PETIT. The seed of Croton Tiglium. 



PIGONIL. A Quito name for Festuca 

 quadridentata, which is said to be poisonous 

 to cattle. 



PIG'S FACES. The fruit of Hesembryan- 

 themum cequilaterale. 



PIGWEED. Chenopodium. 



PILARIS. Composed of small hairs. 



PILEA. A genus of Urticaceas, consist- 

 ing of annual or perennial herbs or under- 

 shrubs, mostly with the aspect of Parieta- 

 ria, but very different in the structure of 

 their flowers. The leaves are always oppo- 

 site, although sometimes one of each pair 

 is very much smaller than the other. The 

 flowers are small and greenish, in little 

 axillary loose cymes or clusters ; the males 

 have a four-cleft perianth and four sta- 

 mens; the female perianth has three divi- 

 sions, of which one is much the larger and 

 thickened or mushroom-shaped at the top, 

 the ovary has a single ovule, and is crowned 

 by a tufted stigma. There are about 330 

 species known, almost all confined or near- 

 ly so within the tropics, in the New as well 

 as in the Old World. One species, however, 

 extends rather far into North America. 

 No one species presents any peculiar in- 

 terest, except it be P. serpyllifolia, the 

 Artillery Plant ; and most of them are in- 

 significant weeds. 



PILEANTHUS. A small genus of Clia- 

 mcelauciacece, consisting of shrubs, with 

 club-shaped leaves, found in South-west 

 Australia. They are distinguished by hav- 

 ing a ten-parted calyx with white round- 

 ish lobes ; a corolla of five petals ; twenty 

 stamens, all fertile, the filaments occasion- 

 ally forked ; and a single style having an 

 obtuse stigma. The flowers are white, 

 axillary or terminal, and surrounded by an 

 involucre. [R. H.] 



PILEATE, PILEIFORM. Having the 

 form of a cap ; or having a pileus. 



PILEOLUS. A little cap or cap-like body; 

 also the diminutive of Pileus ; also the re- 

 ceptacle of certain f ungals. 



PILEORHIZA. The cap of a root; a 

 membranous hood found at the end of the 

 routs of Nuphar and other plants, and dis- 

 tinct from the spongiole. 



PILEUS. A convex expansion termi- 

 nating the stipes of agaricaceous fungals, 

 and bearing the hymenium. 



PILEWOR/T. Ficaria ranunculoides. 



PILL Hairs. Pili polycephali are hairs 

 divided at the end into several arms. 



PILICORDIA. Cordia. 



PILIDITJM. An orbicular hemispherical 

 shield in lichens, the outside of which 

 changes to powder ; as in Calycium. 



PILIFEROTJS. The same as Hair-pointed. 



PILINGRE. (Fr.) Polygonum Persica- 

 ria. 



PILTTIS. A genus of Epacridace.ee, con- 

 taining a single species, P. acerosa, having 

 a sharp-pointed leafy calyx, a corolla with 

 a hood which finally breaks away, and 

 stamens not attached to the corolla. The 

 flowers are terminal, surrounded by sharp- 

 pointed ovate bracts. It is a shrub, having 

 needle-shaped leaves with broad bases, 

 and is found in Tasmania. [R. H.] 



PILLCORN, or PILCORN. Avena nuda. 



PILL DE BRETAGNE. (Fr.) Loliam 

 multiflorum. 

 PILLWORT. Pilularia. 



PILOBOLUS. A genus of vesicular 

 moulds, consisting of two or three species, 

 which grow on dung. When young they 

 are of a bright-yellow hue ; the short stem, 

 however, gradually loses its colour, swells 

 above like the hood of a Cobra, and bears 

 a little vesicle at the apex filled with close- 

 packed dark spores. Accounts have been 

 given of curious motions observed in these 

 plants, but it is believed that they are due 

 to some little worm. [M. J. BJ 



PILOCERETJS. The well-known Old Man 

 Cactus and a few allied species have 

 been separated under this name from the 

 genus Cereus, but, as in other genera of 

 Cactacece, the distinguishing characters are 

 scarcely of generic importance. The prin- 

 cipal differences consist in the flower-bear- 

 ing portion of the plant being unlike the 

 rest, usually forming a dense woolly head 

 at the summit of the stem, and having 

 more numerous, longer and thinner, often 

 hair-like spines ; and the flowers themselves 

 being smaller and having fewer divisions, 

 with the stamens attached to the Avhole 

 surface of the tube. All the species are 

 from Mexico and tropical America. As 

 seen in our hothouses, the Old Man Cactus, 

 P. senilis, is usually a cylindrical-stemmed 

 plant, a foot or more in height ; but in 

 Mexico, its native country, it attains a 

 height of twenty or twenty-five feet, Avith 

 a diameter of nine or ten inches, and its 

 fluted character gives it somewhat the 

 appearance of an architectural column. 

 The stem is divided into thirty or forty 

 narrowf urrows,with corresponding ridges, 

 which are furnished at very short distances 

 with tufts of white spines surrounded by 

 numerous long flexible white hairs resem- 

 bling the grey hairs of an old man's head ; 

 hence has arisen not only the common 

 name of the plant, but also its scientific 

 appellation. When young the stems are 

 fleshy and succulent, but as they get old 

 their tissue becomes filled with an extraor- 

 dinary quantity of small sand-like grains 

 composed of oxalate of lime, not less than 

 from sixty to eighty per cent, having been 

 found in individual stems. [A. S.] 



PILOSE. Covered with hairs ; covered 

 with somewhat erect loose distant hairs ; 

 having the form of hairs. Pilosity is a 

 general term for hairiness ; and pilosiuscu- 

 lus means somewhat hairy. ' 



