White Fibrecap

Description

The white fibrecap is a small, white or cream mushroom with a cap 1–4 cm across, conical, with a distinct umbo and a silky sheen. The gills are at first whitish, then dirty brown, and the stem is thin, white, without a ring. The smell is weak, earthy or mealy.

It grows in groups from summer to November in deciduous and coniferous woods, in parks and by roads. In Poland it is common. There is also a lilac variety.

White specimens are easily taken for young knights or other small mushrooms. The fibrecap is strongly poisonous, and small white mushrooms growing in groups on lawns or road verges are better left alone.

Identification features

Cap

Diameter 1–4 cm; conical, then convex to spread out, always with an umbo in the centre. Pure white or cream when young, turning yellow or brownish from the top in old age. Skin silky, glossy, fibrillose; the margin may split with age. In young specimens the cap is joined to the stem by a cortina.

Hymenophore (underside of the cap)

Gills crowded or moderately crowded, narrowly adnate; whitish to cream or pale grey when young, dirty earthy-brown as the spores mature.

Stem

Height 1–6 cm (most often given as 3–5 cm), thickness 0.3–0.6 cm, cylindrical, white, often crooked, with a small bulblet at the base; when young with cortina remnants at the top, fibrillose-fibrous. No ring.

Flesh

White or cream, does not change colour. Smell weak, earthy, mealy or spermatic (according to some descriptions); taste sharp (according to some descriptions). The taste must not be tested.

Spore print and spores

Spore print brown (clay-brown). Spores ellipsoid to almond-shaped, smooth: 6.5–10.5 × 4.5–6 µm (descriptions also give about 9 × 5 µm).

Habitat and distribution

Ecology. Mycorrhizal fungus; grows in deciduous and coniferous woods, in parks, also on grassy path edges and on dug-up, fertile soil by roads and ditches.

Distribution. Widespread in the Northern Hemisphere (Europe, North America, Asia), in the southern one in Australia and New Zealand. Common in Poland. Not legally protected in Poland. The fruiting bodies grow in groups.

Fruiting. From September to November (descriptions also give: summer and autumn).

What can it be confused with?

• Inocybe umbratica, Inocybe pudica — Microscopy may be needed to tell them apart; details — no data.
• Tricholoma spp. (knights), including Tricholoma terreum — Larger specimens are mistaken for knights, but knights have a mealy smell and gills that stay white, while the fibrecap has gills that turn brown and a brown spore print.
• Calocybe gambosa (St George's mushroom) — Has a mealy smell and the gills stay white; the fibrecap has gills that turn brown.
• Laccaria amethystina (amethyst deceiver) — for the variety lilacina — The deceiver has a fibrous stem, a fruity smell and no ochre umbo; the lilac variety of the fibrecap has an ochre-brown umbo and a mealy or earthy smell.
• Collybia nuda (wood blewit) — for the variety lilacina — Similar colour, but it usually grows much larger.

Never rely on a single feature. If you are not sure — do not pick it; show the mushroom to a qualified mushroom expert.

Interesting facts

• The variety lilacina, with a lilac colour, is sometimes regarded as a separate species; in 1918 Kauffman separated it as a distinct taxon.
• The epithet geophylla comes from Greek words meaning "earth" and "leaf".
• The mushroom is often overlooked by mushroom pickers because of its small size.
• In studies from 2005, analysis of nuclear genes showed a close relationship of I. geophylla with I. fuscodisca, and of I. lilacina with I. agglutinata and I. pudica.