Iodine Bolete

Hemileccinum impolitum

Cap: 5-15cm across  Stem: 5-15cm in length, 2-6cm diameter

hemi meaning 'half' and leccinum from old Italian meaning 'mushroom'

meaning 'unfinished'

Overall: a large robust Bolete that for many years was known as Boletus impolitus. The size, bright yellow pores and no distinctive colour change make this easy to identify.

‚ÄčStem: paler than the pores and sometimes tinged slightly orange/pink towards the base of the stem. Chunky and solid, when cut the iodine smell is quite obvious. The stem is slightly downy but this can fade.

Flesh: no real change in colour when cut, pale yellow - paler than the pores usually. Sometimes a long time after it has been cut it may go slightly pink or blue.

Pores: start pale yellow but quickly become a strong lemon yellow as it ages. Importantly they do not change colour (or at least not distinctly) compared to its look-a-likes.

Cap:  begins velvety and very rounded, becoming flatter, smoother with uneven surfaces as it matures.

OVERALL: A large Bolete which even from a distance is quite distinctive. Usually found with Oak (Quercus) on compacted soil, so oaks growing in parks next to well worn paths is as likely place as any to encounter this species. The specimens photographed here were growing with an oak on a housing estate in north Wales. The brightly coloured pores and flesh that do not change colour when cut or damaged and the smell of Iodine in the base should all point to this species.


HABITAT: grows with Oak (Quercus), very rarely with other tree species.


DISTRIBUTION: Found mainly in southern England where it is Scarce, becoming Rare in the north and rest of the UK.


SEASON: A long fruiting time with records from June through to November, more typically late summer to autumn.


SPORE PRINT: Olivaceous to dirty brown.


ODOUR: Strongly of iodine in the base of the stem, especially when cut.


EDIBILITY: Considered edible but not at all tasty and considered by many to be too rare to justify collecting for the pot, there are far better edible alternatives in this family to bother with this species, for that reason we consider it it Inedible.


SIMILAR SPECIES: The Rooting Bolete (Caloboletus radicans) is a similar size and shape and when dry the cap often goes a darker colour like the Iodine Bolete, but the Iodine Bolete lacks the hard 'wood' like base to the stem. The Iodine Bolete also does not change colour (some change can occur after almost a day) unlike other larger Boletes.


SYNONYMS: Xerocomus impolitus (Fr.) Quel. Boletus impolitus Fr. Leccinum impolitum (Fr.) Bertault.

Tel. 07533 132 129 


Manchester, Cheshire, Deeside & North Wales

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