[Illustration: FIG. 176.--_Armillaria mellea._ (½ nat. size): _a_ root of a Fir; _b_ rhizomorpha-strands; _c-f_ fruit-bodies in four different stages of development.] [Illustration: FIG. 177.--The mycelium of _Armillaria mellea_ (“_Rhizomorpha_”) (nat. size).] About 4,600 species belonging to this order have been described. On account of the large number of species the order is divided into several sections: 1. =Agaricinei=; fruit-body fleshy; lamellæ membranous, knife-like, with sharp edge; basidia crowded together. The FOLLOWING HAVE WHITE SPORES:--_Amanita_ (Fly Mushroom), with volva, and generally also the upper ring on the stalk; many are poisonous, such as _A. muscaria_ (Fig. 178) which has bright red pileus with white spots, _A. pantherina_ and _A. phalloides_; _A. cæsarea_ is edible.--_Lepiota procera_ (Parasol Fungus) is one of the largest Mushrooms; it has a scaly pileus and moveable ring (edible).--_Armillaria mellea_ has been mentioned above (Figs. 176, 177).--_Tricholoma_, lamellæ indented near the stalk; _T. gambosum_ (Pomona Fungus) belongs to the best of edible Fungi; _T. personatum_ often forms fairy rings (see above).--_Clitocybe_, lamella decurrent; _C. nebularis_ is edible.--_Pleurotus_, stalk eccentric; _P. ostreatus_ (Oyster Mushroom) grows in clusters on tree-stems (edible).--_Collybia_ and _Mycena_, species numerous, small.--SPORES ROSE-RED: _Volvaria_ and _Hyporhodius_.--SPORES BROWN: _Cortinarius_, with cobweb-like veil; _Pholiota_, membranous veil and ring; _P. squarrosa_ in clusters on tree-stems; _P. mutabilis_, on tree-stumps (edible).--SPORES VIOLET-PURPLE: _Hypholoma_, _Psalliota_; to this section the common edible Mushroom (Fig. 172–174) belongs, with annulus and chocolate-coloured lamellæ; it is cultivated for the sake of the fine flavour.--SPORES BLACK: _Coprinarius_. [Illustration: FIG. 178.--Fly Mushroom (_Amanita muscaria_).] 2. =Marasmiei.= Fruit-body tough, almost leathery, and persistent; spores white. _Marasmius oreades_ forms large, regular fairy-rings on pastures and commons; it is used as seasoning in food.--_Panus stipticus_ with eccentrically-placed stalk, in clusters on tree-stumps.--_Schizophyllum_ has the edge of the lamellæ divided longitudinally, and the split portions revolute.--_Lentinus_ affords a transition to _Dædalea_ among the Polyporaceæ. 3. =Russulei.= Fruit-body fleshy and fragile, in which two different systems of hyphæ may be distinguished; spores thorny, white, or pale-yellow. Many are poisonous.--_Russula_ has generally fragile and thick lamellæ reaching from stalk to edge of pileus; pileus frequently red.--_Lactarius_ has white or yellow milky juice, which often is very acid. _L. deliciosus_ has red-yellow milky juice, and is of a pleasant flavour. _L. torminosus_ is poisonous.