P. hymenophylloid.es ; with terminal sori 

 on punctiform receptacles and adherent 

 fronds, as in P. suspension; with medial sori 

 and adherent fronds, as in P. Phegopteris ; 

 and with hasal sori and adherent fronds, 

 as in P. tenuisectum. The fronds vary from 

 simple to decompound in form, and from 

 membranaceous to coriaceous in texture ; 

 while their size is equally varied. [T. M.] 



POLYPODY. Polypodium. — of the 

 Oak. Polypodium vulgare. — , COMMON. 

 Polypodium vulgare. — , FEMALE. Athy- 

 rium Filix-fcemina. —, MALE. Lastrea 

 Filix-mas. 



POLYPOGON. A genus of grasses he- 

 longing to the tribe Agrostidece. The inflo- 

 rescence is in densely contracted panicles; 

 glumes unequal, more or less hairy and 

 compressed, with bristles or very sharp 

 points ; pales shorter than the glumes, 

 the lower with a bristle under the apex. 

 There are twenty-four species described 

 by Steudel, which have a considerable geo- 

 graphical range, extending from Western 

 France to Central Asia. P. monspeliensis 

 and P. littoralis, the only species belong- 

 ing to the British Flora, are confined to 

 England. There are several handsome 

 grasses among them, though mostly worth- 

 less for agricultural purposes. [D. M.] 



POLYPORTJS. An enormous genus of 

 pore-bearing Fungi distinguished from 

 Boletus by the tubes not separating from 

 each other or from the pileus. The species 

 vary much in point of substance, a few 

 being so soft as to be esculent, and others 

 hard and woody or corky. Our European 

 species are numerous, but while the tropics 

 have many species in common with other 

 zones, they have hosts of species which 

 require a high temperature. Polypori are 

 frequently resupinate, and glued down to 

 the matrix ; the margin alone in others 

 becomes free ; then the whole is free but 

 sessile; then the pileus contracts behind, 

 acquires a short stem, by easy grada- 

 tion becomes central, and finally is borne 

 like an umbrella on a tall well-formed stem. 

 One of the finest, P. sacer, is an object of 

 worship in Guinea. Some of the species 

 are of a brilliant scarlet, others lilac, yel- 

 low, orange, &c, but the predominant 

 colours are tints of brown. The pores vary 

 much in size, being sometimes almost in- 

 visible to the naked eye. A few, as P. 

 ovinus, afford a grateful food ; but in gene- 

 ral, like P. squamosus, they are not only 

 coarse, but tough and indigestible. P. tu- 

 ber aster, which springs from the Fungus 

 Stone (see Pietba Ftjxgaja), is esteemed 

 in Italy, and a species is raised from pollard- 

 hazels by roasting them gently before the 

 fire and then keeping them properly irri- 

 gated. P. fomentarius supplies the best 

 Amadou of commerce, though inferior 

 kinds are produced from other species. P. 

 officinalis was once a celebrated drug, but 

 it is now little used, though still to be ob- 

 tained in the herb-shops ; it grows almost 

 exclusively on Larch. P. destructor and 

 some others are the pest of wooden struc- 



tm-es, while the spawn of P. liybridus is 

 the dry-rot fungus of oak-built ships. P. 

 betulimis, when cut into strips, forms ex- 

 cellent razor-strops. [M. J. B.] 



POLYSACCUM. A genus of puff balls re- 

 markable for containing a multitude of 

 small partial peridia within the common 

 irregularly bursting envelope. These in 

 an early stage are pulpy, but they are soon 

 indurated and ultimately contain a mass of 

 threads and spores, the latter of which are 

 larger than in most Lycoperdinei : the ma- 

 ture plant is extremely rigid and brittle. 

 The species are divisible into two sections— 

 the first of which includes the larger kinds 

 which have a stout stem, divided and 

 rooting at the base, with a clavate or round- 

 ed head ; the second those with a short 

 abrupt stem, giving off a few roots only. 

 Fries gives a third section consisting of 

 ill-known species in which there are neither 

 stems nor roots. The species inhabit 

 sandy tracts in warm countries, a single 

 specimen only having occurred on com- 

 mon soil in the neighbourhood of London. 

 In Italy one species at least is said to pro- 

 duc e a yellow dye. [M. J. B] 



POLYSARCIA. An excess of sap, giving 

 rise to unnatural growth, &c. 



POLYSIPHONTA. A large genus of 

 rose-spored Algce belonging to the natural 

 order Bhodomelacew, characterised by its 

 thread-shaped articulated fronds with the 

 surface-cells arranged in transverse rows 

 so as to produce a pretty striated appear- 

 ance. The species occur in all parts of the 

 world from the polar seas to the equator, 

 and are abundant on our coasts. Sections 

 of the stem are pretty objects under the 

 microscope, resembling wheels with anave 

 and radiating spokes. P. fa -stigiata is per- 

 haps the most familiar species, forming 

 brown bushy tufts on Funis nodosus in 

 America as well as in this country. A 

 section of the stem has the peculiarity of 

 showing a dark endochrome in the midst 

 of the nave. [M. J. B.] 



POLYSPOROUS. Containing a great 

 many spores. 



POLYSTACHYA. Chiefly an African 

 genus of orchids, the main exceptions 

 being two "West Indian and tropical Ame- 

 rican species, one of which is also found in 

 Ceylon. It belongs to the Maxillaruke 

 group of Vandcce, and is characterised by 

 having its lateral sepals broader than the 

 other and adnate to the prolonged foot of 

 the short semiterete column, its lip three- 

 lobed, cushioned on its disk, and articulate 

 with the column, and its four collateral 

 pollen-masses attached by a setaceous cau- 

 dicle to a minute gland. The species are 

 epiphytes, usually of small size, with or 

 without pseudobulbs, and small not showy 

 flowers in simple or compound terminal 

 spikes. [A. SJ 



POLYSTEMMA viridiflora is the sole 

 representative of a genus of Asclepiadaccae 

 inhabiting the mountains near Orizaba, 

 in Mexico. It is a twiner, with densely 



