The Orangefoot Bolete (Hortiboletus engelii) is a small, slender bolete with a flattened, dry, finely felty cap in yellowish-brown to buff tones that flushes pinkish with age. The pores are curry-yellow to greenish-yellow and darken to grey-blue where handled. The tapering yellow stem carries fine red dots or streaks in the middle, and the base is marked with distinctive orange spots.
It is widespread and locally common in the UK, fruiting from June to September in parks and open spaces with oak (Quercus), where it forms a mycorrhizal partnership with the tree. Fruiting bodies are often found singly or in small scattered groups.
It is easily confused with other red-stemmed boletes, especially the Ruby Bolete (Hortiboletus rubellus), which has a much redder cap when fresh, and Rheubarbariboletus armeniacus, which lacks red on the stem. Separation can need cross-sections and a microscope. Hortiboletus species are not regarded as worthwhile edibles and are often maggoty, so it is best left alone, and no bolete should be eaten unless identified with certainty.
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Distribution
Widespread and locally common
Habitat
In parks and open spaces with Quercus
Etymology
Hortiboletus combines the Latin hortus, meaning garden, with Boletus, from the Greek bolos, meaning a lump of clay, and refers to the garden-like parks and open spaces where these boletes often grow. The epithet engelii honours the German mycologist Heinz Engel, who did pioneering work on boletes in the late 20th century and had earlier used the provisional name Xerocomus quercinus for this species.
Associates
Quercus
Cap
The dry, finely felty cap takes on a pinkish flush as the fruit body ages, softening the yellowish-brown to buff colour of younger caps.
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| Width | 3 - 8 cm |
Pores
Pores open as round to angular tube mouths, curry-yellow at first and shifting towards greenish-yellow, and in older fruit bodies they may darken to orange-brown. They slowly stain greyish-blue when touched, though the reaction can be weak.
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Tubes
The tubes are yellow to greenish-yellow, matching the pore surface, and are attached to the stem with a slight notch or tooth. They are fused together, so they tear when pulled apart.
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Flesh
The flesh is soft and pale yellow, with a reddish-purple line just under the cap skin. In the stem it is deeper yellow towards the base, where it carries tiny orange dots. Blueing is slight and mostly confined to the upper stem and the area above the tubes. Smell is pleasant and taste mild.
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| Odour | Pleasant |
| Taste | Mild |
Stem
The middle of the stem carries red dots or short red streaks. The upper stem and the area just above the tubes bruise blue when handled, and the lower stem is marked at the base with intense orange spots.
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Macrochemicals
A 2025 study (Biketova et al.) found 20% KOH gave reddish-brown on the cap surface and pores, pink on the cap flesh, and bright orange on the stem surface and flesh, darkening towards the base. Ammonia (25% NH4OH) gave no reaction or a pale yellowish tinge throughout.
Spores
Spores are smooth and subfusiform, a little unequal-sided in side view, and typically contain one or two large oil droplets. They are straw to honey-yellow under the microscope in water or KOH. The spore print is deep olive.
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| Size | 10.3-14.3 x 4-6.4 μm |
Microscopic Features
Both pleurocystidia and cheilocystidia are slender and ventricose-fusiform, with a long, straight or wavy neck and a rounded tip. They are smooth and colourless to pale yellowish in water and KOH. Pleurocystidia are infrequent, while cheilocystidia are scattered along the tube edges. Both average roughly 65-70 x 10 µm.
Classification
- ↳ Phylum: Basidiomycota
- ↳ Subphylum: Agaricomycotina
- ↳ Class: Agaricomycetes
- ↳ Subclass: Agaricomycetidae
- ↳ Order: Boletales
- ↳ Family: Boletaceae
- ↳ Genus: Hortiboletus
Synonyms
- Boletus armeniacus sensu Dennis (1995)
- Boletus communis sensu auct.
- Boletus declivitatum (C. Martín) Watling
- Boletus declivitatus (C. Martín) Watling
- Boletus engelii Hlaváček
- Boletus subtomentosus subsp. declivitatum C. Martín
- Boletus subtomentosus subsp. declivitatus C. Martín
- Xerocomellus engelii (Hlavácek) Šutara
- Xerocomellus engelii (Hlaváček) Šutara
- Xerocomus communis sensu Bon (Doc. Mycol. 14 (no. 56): 16 (1985) [1984]), sensu auct.
- Xerocomus declivitatum (C. Martín) A.E. Hills ined.
- Xerocomus declivitatum (C. Martín) Klofac
- Xerocomus engelii (Hlaváček) Gelardi
Reference Sources
G. Kibby (2017) British Boletes with keys to species. Geoffrey Kibby.
T. Læssøe, J. H. Peterson (2019) Fungi of Temperate Europe Vol. 1. Princeton University Press.
G. Kibby (2020) Mushrooms and Toadstools of Britain & Europe Vol. 1. Geoffrey Kibby.
