Peniophora was separated from Corticium because of the presence of ancillary organs which Cooke termed “metuloids” and by later workers were named cystidia. These are of various shapes and may bear exteriorly coarse, usually deciduous crystals of calcium salts, the common condition as in the type species P. quercina; be covered with tuberculate crystals scattered or arranged like scales, as in P. longispora; be naked and project for the greater part of their length, as in P. gracillima; be naked, projecting, and enmeshed within a network of hyphae, as in P. vermifera. The value of various differential features employed by workers for separation of species, and for grouping them into various sections, is discussed below.
Hymenophore Surface colour was used by earlier workers as a specific character, and is still used in part as a group feature by workers who would maintain the section “Coloratae” of Bourdot & Galzin (1928, 319). It possesses little diagnostic value, however, since most species are white or cream, and remain so when dried or in the herbarium may change to isabelline. In the P. cinerea and P. incarnata groups, colour is noteworthy. P. cinerea and its allies are some shade of grey with brown context and coloured hyphae P. incarnata and related species are flesh-pink, orange, or some shade of red, with hyaline hyphae and white context. A few extralimital species exhibit distinctive colours, as blood-red in P. sanguinea, orange in P. aurantiaca, and tobacco-brown in P. dryina
Shape and size are likewise valueless save in a few species. All species are resupinate; pileate forms bearing cystidia, treated by various workers under Peniophora or Stereum, are in this series referred to Lopharia for reasons which will be discussed under that genus. Most are effused, forming irregular fructifications on bark or decorticated wood or dead branches, twigs, or trunks. A few develop as scattered maculiform colonies which may remain discrete or merge to form effused fructifications. Noteworthy species are P. hastata, which produces small maculiform colonies in bark crevices, P. umbracula and P. vermifera, fructifications of which are maculiform and chalky.
Texture of the context has been used as a group feature by Bourdot & Galzin (1928). They divided species into sections which were held to be ceraceous, membranaceous, pelliculose, byssoid, arachnoid, arescent or coriaceous. But as they themselves often failed to place species correctly, and as texture varies appreciably according to age, habitat, or climatic range, it is evident that it is an unreliable group feature. Chalky species, for example, owe their condition to masses of crystals crowded in the context; yet crystals may be wanting in collections of species in which they are normally present, when the texture appears membranous or ceraceous.
Whether the surface is even, slightly tuberculate, farinose, velutmate, or variously creviced is likewise relatively insignificant. Most species are even, many creviced, and if farinose or velutinate usually owe this condition to projecting cystidia or gloeocystidia. These last may disappear with age or through rough handling.
Marginal features are seldom significant. Most species have margins which thin out gradually and are fibrillose or arachnoid. In perennial species margins are sometimes abrupt and cliff-like, or receding with each successive layer, more or less accidental conditions. Noteworthy exceptions are P. filamentosa and the related P. radicata which often, though not invariably, possess marginal rhizomorphs. Most fructifications are adnate, firmly attached to the substratum; a few may be attached loosely and tend to peel from the substratum when old, or weathered.
In sum, it is seldom possible to identify a species accurately by means of macrofeatures, though some occasionally may be used to group related species into sections. Consequently, in this series, microfeatures alone have been employed for delimitation of species, and for grouping them into sections containing related species.
Context. Species may be annual, biennial, or perennial. Most are annual with a relatively brief period of growth. Stratose species are normally perennial, as many as 30 layers of replicated tissues developing layer upon layer in the same fructification. It is probable that all species of the P. cinerea group are perennial, as are P. cerebrosa, P. crustosa, P. erucaeforma, P. sacrata, P. scintillans and P. totara. Perennial species contain numerous layers of cystidia, either arranged in definite zones with parallel hyphae between (Fig. 12), or in overlapping rows spaced regularly or irregularly (Fig. 10). In P. crustosa the context is composed of many hyaline and brown alternating zones (Fig. 13). each brown zone owing its colour to bands of mucilaginous granules lying parallel with the surface and coating hyphae and cystidia.
Hyphae of the context are usually arranged in two definite tissues; a basal layer lying upon the substratum with hyphae predominantly parallel (Fig. 9),
and an intermediate layer with hyphae ascending. The basal layer is commonly scanty, often reduced to a few repent hyphae; in P. coprosmae, P. filamentosa and P. rimicola, on the other hand, it is strongly developed and occupies the greater part of the context. The intermediate layer is usually well developed; among its hyphae may lie most of the ancillary organs when they are not confined to the hymenial region, consequently sections are necessary to demonstrate their arrangement and manner of origin. The intermediate layer is suppressed in P. rimicola, P. vermicularis, P. vermifera and P. thermometra, basidia and paraphyses arising directly from superficial hyphae of the basal layer. Most hyphae of the intermediate layer are ascending, either vertically in a densc palisade as in P. erucaeforma and P. gracillima; cemented into a honeycomb tissue as in P. sacrata; intertwined as in most species; or branched at a wide angle as in P. cremea.
Hyphae may be naked, as in most species, zoned with gelatinous granules as in P. crustosa, or coated with granules of mucilage as in P. filamentosa. They may be coated with crystals, as in P. cerebrosa, or crystals may be confined to the upper hyphae of the intermediate layer, as in P. cremea, P. longispora and P. sambuci. Masses of crystals are often present among the context hyphae, and may be abundant or scanty in collections of the same species. Hyphae of large diameter are present in the context of P. cremea and P. filamentosa. In most species the context is white, with hyaline hyphae; but in P. cinerea, P. lycii and P. nuda hyphal walls are coloured brown P. filamentosa possesses hyaline hyphae. but in sections they appear to be ferruginous, colour being produced by masses of brown mucilage granules coating their walls.
Cystidia. Species have been arranged herein into two sections, the “Pedicellatae” and “Radicatae”. In the former cystidia are composed of two parts, a basal pedicel and a modified continuation of it upon which crystals are carried. Cystidia may be cylindrical, aculeate, conical, fusiform, oval, or elliptical, and often vary appreciably both in shape and size in the same species. They are continuous in most species, but septate in P. erucaeforma (Fig. 15) and the extralimital P. aspera, P. byssoides, P. pallidula and P. polonensis. Most are submerged in tissues of the context and/or hymenium, though those developed in the tissues of the hymenium and subhymenium may project slightly. Cystidia arise from hyphae of the basal layer, intermediate layer, hymenium or subhymenium.
Crystals may cover the entire modified portion, as with most species in the section, be confined to the apical region as in P. cremea, or the apex may remain naked, as in P. erucaeforma and P. sororia. Crystals are usually angular and coarse; in P. verecunda they are rod-shaped (Fig. 6), and in P. longispora and P. sororia (Figs. 18, 19) flattened and patelliform. Most are partly or completely deciduous, so often disappear from permanent mounts, or from cystidia in the base of old plants. They are highly refractive and so conspicuous in sections when examined under the microscope.
In the section “Radicatae” cystidia arise directly from hyphae in the base of the context and project for at least half their length above the hymenium. They are modified basally, being sessile and without pedicels, and are either inflated, extended laterally, or bear two or several radicate extensions (Figs. 22, 23). Walls are thickened appreciably, often to such an extent that the lumen becomes capillary (Fig. 27), and are usually dissolved or distorted when treated
with a 10 per cent. solution of potassium hydroxide. Cystidia of P. gladiola, P. hastata, P. thermometra, P. vermicularis and P. vermifera are enmeshed within a network of delicate hyphae (Fig. 24); in P. umbracula they bear apically a parasol of fused crystals (Fig. 28), a feature also present in the Canadian P. hamata. Those of P. gracillima and P. thermometra resemble miniature thermometers (Figs. 27, 29), with the lumen of the stem so reduced by thickening of the walls as to be capillary, the apex remaining thinwalled. In P. thermometra the apex is inflated, thus increasing the resemblance.
Gloeocystidia. Seven of the species present in New Zealand bear these organs. Most gloeocystidia are cylmdrical or flexuous-cylindrical; m P. inconstans they are elliptical or oval (Fig. 7), and in P. nuda (Fig. 3) clavate or pyriform. They arise usually from tissues of the basal layer, but in P. vesiculosa and P. utriculosa develop from hyphae of the intermediate layer (Figs 4, 5). Walls are naked, and in actively growing plants cell contents are yellow and granular or oily, these two features differentiating glococystidia from cystidia.
Vesicles. Present in three New Zealand species, vesicles appear to be rare in the genus, since they have been recorded for only one [ unclear: ] species, P. mutata. Pyriform in P. vesiculosa and P. utriculosa (Figs. 4, 5), where they develop from hyphal branches of the intermediate layer, in P. verecunda they are capitate (Fig. 6) and borne on simple stems arising from hyphae of the basal layer. They may be abundant or scanty, but are always present, though not always easy to demonstrate in old tissues.
Spores. Smooth in most species present in New Zealand, spores are delicately verruculose in P. hastata, P. inconstans and P. rimicola. Spores of most species are elliptical, elliptical with one side flattened, or suballantoid. They are pipshaped in P. cerebrosa and P. vesiculosa, globose in P. inconstans and P. thermometra, and cylindrical in P. longispora. Spores of unusual shape are found in P. vermifera, being flexuous-naviculate with long-acuminate often geniculated apices (Fig. 24). In P. vermicularis they are lunate (Fig. 25). It is advisable to examine spores attached to sterigmata for shape and size, thus avoiding the common error of mistaking for those of the species under consideration, spores of contaminating moulds.
Hyphal System. All species described herein are monomitic—that is, they are composed of generative hyphae alone. Possibly all species are monomitic, since none with a dimitic hyphal system was seen in Kew herbarium. “Peniophora” cinerascens possesses a dimitic hyphal system. Placed under Peniophora by certain workers or under Stereum by others, it and “Peniophora” vinosa will be treated under Lopharia in this series.
Clamp connexions are present in all save six of our species—namely, P. cremea, P. crustosa, P. erucaeforma, P. filamentosa, P. rimicola and P. sacrata.
Basidia, Paraphyses and Paraphysate Hyphae. Basidia are usually subelavate or elavate, although in P. inconstans they are cylindrical with a constricted middle (Fig. 7). Most range from 15μ to 25μ in length, but are appreciably larger in P. gladiola, P. sacrata and P. utriculosa and smaller in P. thermometra. Nearly all bear four spores on sterigmata, though in P. gladiola 2-spored basidia are not uncommon, and in P. vermifera they may carry 1, 2 or 4 spores. Save for these exceptions, basidia exhibit no features of diagnostic value.
Paraphyses resemble basidia in shape, differing mainly in being smaller. They also possess no features of diagnostic value.
Paraphysate hyphae of unusual form occur in four species. In P. lycii they are freely branched, crystal coated and in shape resemble dendrophyses (Fig. 1.) Apices are capped with acicular crystals in P. gladiola (Fig. 22); and in P. rimicola and P. verecunda (Fig. 6) they are capitate with simple stems.
Substratum. Most species develop upon bark or decorticated wood of a wide range of hosts. P. coprosmae grows upon several species of Coprosma, but is not confined to members of that genus; P. totara is limited to two species of Podocarpus; P. vermicularis shares with two species of Corticium and an Epithele dead pendent stipes of tree ferns.
Chemical Tests. Use has been made overseas of tests for amyloidity of spore walls, walls of hyphae and cystidia by treatment with Melzer's Solution (0.5 gm iodine, 1.5 gm potassium iodide, 20 gm chloral hydrate, 20 ml water). Similarly a 10 per cent. solution of potassium hydroxide has been used as a test reagent on cell walls of cystidia of the radicate section. In my experience both tests are too uncertain in their reactions to provide a unit of measurement for grouping related species, since positive, indefinite or negative results often may be secured with different sections from the same species.
Illustrations. Text figures are correct for scale, size and shape of structures they illustrate. Obscuring mineral matter hyphal chips, and the like. have been omitted, since their inclusion would obscure diagnostic features. For their preparation numerous sections were made from different parts of each collection, so that details of development, structure, ancillary organs, etc., could be interpreted correctly. All were drawn to the same magnification and reduced proportionately.
I am indebted to Miss Beryl Hooton, librarian, for preparation of Latin descriptions; and to Misses W. M. Tombs and E. Maisie Smith for suggesting many specific names.
7. Peniophora Cooke, Grevillea, 8. 20. 1879.
Gloeopeniophora Hoehn & Litsch., Sitz K. Akad Wiss., Wien, 116. 815, 1907.
Gloeocystidium Hoehn & Litsch, Weisner Festschr. 58, 1908. non Karsi. 1889.
Gloeopeniophorella Rick, Bot. Cienc Nat, 3, 47, 1934.
Crystallocystidium Rick. Bioteria, 9, 139, 1940.
Hymenophore resupinate, annual, biennial or perennial, effused; surface plane, creviced or entire, white or coloured. Context composed of one or several strata, each consisting of a basal layer of parallel hyphae, with usually an intermediate layer of ascending hyphae from the apices of which the hymenium is developed, hyphal system monomitic generative hyphae hyaline or coloured, branched, septate, naked or coated with crystals of mucilage granules, with or without clamp connexions. Hymenial layer composed of a palisade of basidia and paraphyses, associated with cystidia and in some species gloeocystidia or paraphysate hyphae. Basidia subclavate, clavate, or cylindrical, projecting or not, bearing two or four spores on sterigmata. Cystidia pedicellate when coated wholly or in part with deciduous crystals, or sessile when naked or enmeshed in a hyphal sheath; of various shapes, commonly aseptate. Gloeocystidia of various shapes, thin-walled, aseptate, naked, hyaline. Vesicles unicellular, pyriform or subglobose. Paraphysate hyphae branched or simple, sometimes crystal
coated, bearing an apical cap of crystals, or naked and capitate. Spores variously shaped, walls smooth or verruculose, hyaline or tinted.
Type Species. Peniophora quercina (Pers. ex Fr.) Cke. Distribution. World-wide.