_General Information_: This is one member of a whole complex group of ochraceous, brown, tawny or cinnamon-brown capped agarics which superficially appear to be the same, but on closer examination the expert can split them into several distinct species. The use of microscopic characters is essential and outside the scope of this book or the ordinary mushroom-picker’s manual. However, the closely related _C. lactea_ (J. Lange) Métrod can be more easily distinguished for it has a white or cream-coloured cap and stem. It also has larger broadly ellipsoid spores, measuring 12-14 × 6-9 µm, but the same shaped cells on the gill-edge. _Illustrations_: LH 153; NB 35⁴; WD 68². [Illustration: Plate 35. Fleshy fungi: Spores brown and borne on gills] (d) Fairy-ring formers Many agarics grow in circles, but not all of them produce zones in the vegetation. It is the distinct zonation caused by the ‘fairy-ring champignon’ _Marasmius oreades_ (Fries) Fries and related fungi which have given rise to the name of Fairy-ring and which resulted in the foundation of many folk tales. A fairy-ring can be divided into four distinct zones, a central zone of fairly normally developed vegetation on the outside of which is a green, actively growing zone of grass; outside this is a zone composed of brown or dead vegetation. The outermost zone again appears to be far more lush than the normal grass in the vicinity and it is in this last zone that the fruit-bodies of the fungus causing the pattern appear. A generalised explanation of the zoning appears to be as follows:-- In the outermost zone the actively growing mycelium decomposes soil constituents and liberates nitrogenous material which is in turn taken up by the plant roots nearby and utilised for their growth. In the penultimate zone the grass is dead, probably not caused by a direct parasitic attack but by the mycelial threads filling the air-spaces in the soil and so inhibiting water flow. This destruction of the delicate balance of water and air found in any soil induces drying out and gradual death of the plants whose roots permeate the soil. Behind the dead-zone is vegetation which shows increased vigour apparently due to plant-nutrients being released by the decaying mycelium and plant-material, whose death has been caused by the presence of the fungus. The innermost zone is not so stimulated. With nothing more than graph and tracing paper, a tape-measure, note-book and pencil, pieces of cane about four inches long, and coloured dye or indian ink, it is exciting to assess the annual radial growth of fairy-rings and to correlate these with environmental conditions. This can be carried out on a school lawn or on a home lawn; the method and further experiments are given in Appendix iii. [Illustration: Plate 36. Fairy-ring fungus--~Marasmius oreades~] ~Marasmius oreades~ (Fries) Fries Fairy-ring champignon _Cap_: width 25-60 mm. _Stem_: width 5-9 mm; length 30-80 mm.