Greenflush Fibrecap

Greenflush Fibrecap is a comparatively large and solid member of Inocybe, notable for the green pigment that suffuses the centre of its otherwise pale straw to ochre-buff cap. The tint varies from a subtle olive haze to a clear blue-green patch across the umbo, and it is strongest in fresh, young fruitbodies growing in shade.

Along with Inocybe fraudans it belongs to the small group of aromatic fibrecaps, giving off a sweetish scent that observers variously describe as fruity, pear-like or faintly aniseed, rather than the earthy-spermatic odour typical of the genus. The combination of green flush and sweet aroma is unusual enough to make field identification straightforward compared with most fibrecaps.

Structurally it is a smooth-spored species with a fibrillose to slightly scaly cap surface and a stout, often bulbous-based stipe. It is a woodland fungus of richer, frequently calcareous soils, forming mycorrhizal relationships with broadleaf trees.

Cap

3–8 cm across, convex with a broad umbo, expanding to almost flat. The ground colour is pale straw, cream-buff or greyish-ochre, and the surface is dry, radially fibrillose and often breaking into small appressed scales toward the centre. A blue-green to olive flush is present over the umbo and disc, sometimes spreading in patches across the cap, and fades with age and drying.

Gills

Adnexed, crowded, whitish to pale grey when young and maturing through clay-buff to dull olive-brown. The edges are paler and finely fringed, and may show faint greenish tints in very fresh material near the stipe.

Stipe

4–10 cm tall and 8–18 mm thick, fairly stout, cylindrical with a swollen or clavate base that may be slightly rimmed. It is whitish to pale buff, pruinose in the upper part and fibrillose below, and can show a greenish tinge at the very base. No ring is present.

Flesh and spore print

Flesh is white to pale cream, sometimes with greenish tones under the cap cuticle and occasionally flushing faintly reddish in the stipe. The odour is sweetly aromatic and fruity. The spore print is snuff-brown; spores are smooth and almond-shaped, without nodules.

Greenflush Fibrecap grows from soil in broadleaf and mixed woodland, preferring richer, neutral to calcareous ground under beech, oak, lime, hornbeam and hazel, and sometimes appearing with conifers in mixed stands. It also occurs in old parkland, wooded gardens and shaded avenues with mature trees.

Fruiting runs from late summer to autumn, with fruitbodies appearing singly or in small scattered groups, often along path edges and on shaded banks. The species is widespread across Europe and reported from temperate North America and Asia, though it is nowhere especially common.

This is an ectomycorrhizal fungus that forms sheathing associations with the roots of broadleaf trees. The fungal mantle and the network of hyphae radiating from it greatly extend the volume of soil from which the host can draw nitrogen, phosphorus and water, while the tree supplies carbohydrates to the fungus. Its preference for base-rich soils suggests a relatively narrow tolerance compared with generalists like Inocybe geophylla.

The green pigmentation of the cap is chemically related to the compounds responsible for the sweet aroma, and both are concentrated in the cap cuticle and the upper flesh. As the fruitbody ages and dries, both the green colour and the scent diminish, so weathered specimens can be much harder to place.

Inocybe fraudans is the closest match in size, colour and aroma, but lacks the blue-green flush and instead reddens strongly where bruised or aged. Inocybe rimosa is more conical, warmer straw-ochre, splits far more deeply and has an earthy rather than fruity odour.

Inocybe calamistrata also carries green pigment, but there it is confined to the base of a densely scaly dark brown stipe, and the whole fungus is much smaller and darker. Pale Hebeloma species overlap in colour and habitat but have smooth, slightly viscid caps with no radial fibrous texture and a radish-like odour.