~Oxyporus populinus~ (Fries) Donk, grows on various sorts of broad-leaved trees, particularly poplars and often becomes covered in mosses and algae. It has a pale buff or cream-coloured cap, white flesh, pores, tubes and spores. _Illustrations_: LH 67. ~Cryptoderma pini~ (Fries) Imaz, grows on conifers often several feet above the ground. It has a woody, deeply cracked upper surface, dark red-brown flesh, tubes and pores. Its spores are small, broadly ellipsoid and brown. ~Heterobasidion annosum~ (Fries) Brefeld Root fomes Variable, sometimes possessing a cap, sometimes resupinate except for the upturned margin, flattened or shell-shaped, red-brown to blackish at the centre but pale at the margin, which when seen from below is always white. The tubes are in layers and like the pores, flesh and spore-print are white. The spores are broadly ellipsoid, small, smooth, hyaline and 4-5 × 4 µm. The flesh is fairly tough as it contains both generative hyphae and skeletal hyphae. It is frequent on the roots and lower parts of stems of many trees and shrubs causing a rapid heart-rot of conifers and extensive damage to young trees. _Illustrations_: LH 67; NB 111¹; WD 98¹. The spores of all the perennial polypores described above do not blue when placed in solutions containing iodine. [Illustration: Plate 48. Woody fungi: Spores borne within tubes--perennial polypores] ~Schizophyllum commune~ Fries Split-gill fungus _Cap_: 10-25 mm. _Stem_: width 2-4 mm; length 2-4 mm. _Description_: Cap: greyish fawn becoming whitish when dry, fan or kidney-shaped, often lobed and covered in close-set hairs and with incurved margin. Stem: absent or the cap simply narrows into a stem-like bump. Gills: replaced by a series of grey-brown plates which when dry appear as if to split longitudinally and their edges roll back. Flesh: brownish but drying whitish. Spore-print: white. Spores: medium sized, oblong, hyaline under the microscope, not blueing in solutions containing iodine and 6-7 × 2-5 µm in size. Facial and marginal cystidia: absent. _Habitat_ & _Distribution_: Grows on fallen branches, trunks, dead wood, etc. _General Information_: Easily recognised by the ‘gills’ radiating from a point and becoming ‘split’ when dry. Specimens of _Schizophyllum_ sealed by A. H. R. Buller in a tube in 1911 have been shown on remoistening to unroll their gills and shed variable spores, after 52½ years--probably a world record! The split-gill is a rather unique British fungus which appears to be much more closely related to the polypores than to the agarics--although it has for a long time been associated with the Oyster mushroom (p. 74). In fact, the splitting gills are two adjacent shallow dishes with spores produced on their inner surfaces. The cups separate on drying and therefore only superficially resemble gills splitting down the centre.