Orange-latex Milky

Appearance

The cap is 3 to 10 cm, rarely up to 12 cm wide and more or less centrifugal-shaped and round. It is at early stage convex and furled on the slightly churlish edge, and depressed in the centre and later flat, funnel-shaped depressed. The cap skin is bare, greasy in moist weather and slightly shiny when dry. The cap is tangerine to orange-brown, darker zoned towards the edges and dulls mainly yellow-brown. In old age or after cold or frost it changes the colour more or less to dirty greenish or green-spotted.

The dense, bow-like lamellae are pale-orange to pale-ochre and on the stipe basifixed or slightly decurrent. They are brittle and intermixed with shorter lamellulae as well as partly forking near the stem. In old age or in cases of injury they receive initially dark red, later grey green spots. The spore print is pale ochre.

The mainly long and cylindrical stipe is reddish orange. It is 4 to 8 cm long, 1 to 1.5 cm wide and barely foveate or blotchy. On the basis it is often slightly thickened or pompous and becomes hollow inside. A bloomy circular zones is found on the lamella disposition.

The milk is first carrot-red and becomes a maroon colour within 10 to 30 minutes. The brittle and pale-yellowish flesh is often infested with maggots. If cut or injured it becomes, as the milk, first carrot-red, then maroon and within hours dirty green. The fruit body smells harsh, fruit-like and first tastes mild, but then slightly resinous-bitter and nearly spicy or somewhat astringent.The rotund to ellipsoid spores are 7.5–10 µm long and 6–7.6 µm wide.

The surface ornamentation extends to 0.5 µm high and is mainly from warts and short, wide ridges, which are linked through few fine lines to form an incomplete net. The suprahilar area, a distinctly limited zone above the apiculus, is weakly amyloid. Basidia are four-spored and measure 45–60 × 9.5–12 µm. They are roughly cylindrical to somewhat club-shaped and often have an oil droplet or a granular body. The sterigmata are 4.5–5.5 µm long. The thin-walled pleurocystidia are sparse, but somewhat common near the gill edge.

They are protruded and are 45–65 µm long and 5–8 µm wide, they are sometimes smaller near the gill edge. Nearly spindle-shaped, they are often straightened or constricted like a string of pearls at the apex. The body is often fine and grained. Pseudocystidia are largely present. They are 4–6 µm wide and are sometimes protruded, but are often shorter than the basidioles. The basidioles are cylindric to spiral and have an ochre-coloured substance, similar to the laticifers.

Near the top they are, however, almost hyaline. The gill edge is usually sterile and has a few to many cheilocystidia. The thin-walled cheiloleptocystidia are 15–25 µm long and 5–10 µm wide. They are almost club-shaped or irregularly shaped and transparent, and often contain a granular material.

The cheilomacrocystidia are also thin-walled and measure 25–50 µm long and 6–8 µm wide. They are slightly spindle-shaped and often have a tip resembling a string of pearls; their interior is hyaline or granular. Laticifers are abundant, striking and body is ochre coloured. The cuticle of the cap is an ixocutis, whereby the hyphae are linked in a jellylike matrix, that can swell up in moisture to become heavily slimy.

Naming

The likewise very common "Lactarius deliciosus" is similar in appearance. "Lactarius deterrimus" differs basically from the first because its flesh becomes reddish within 10 minutes and in about 30 minutes dark maroon, caused by the discolouration of the milk. The milk of "L. deliciosus" stays orange or becomes reddish within 30 minutes. Also, the milk of the latter tastes mild, while the milk of the first distinctly bitter. The cap of "L. deterrimus" changes its colour in old age or if injured distinctly greenish and is common only under spruces, while "L. deliciosus" is native under pines.

Even more similar is the very rare "Lactarius semisanguifluus". Its milk also discolours within 5 to 8 minutes to maroon. The cap of older fruit bodies is nearly completely greenish. It is also common under pines. The most similar and also the most closely related fungus is "Lactarius fennoscandicus", a boreal to subalpine species. Its cap is distinctly zoned and brown-orange. Sometimes the cap has purple-grey tones. The stem is pale to blunt orange-ochre.

Distribution

"Lactarius deterrimus" is mainly distributed in Europe, but the fungus has also found in areas of Asia. According to recent molecular biologic research, the similar North American species from the United States and Mexico are not closely related to the European species. In Europe, the fungus is especially common in Northern, North-East and Central Europe; in the UK, it may be found from July through to November. In the south and west it is common in mountainous areas. In the east, its range extends to Russia.

Habitat

"Lactarius deterrimus" has traditionally been considered to have a strict mycorrhizal host specificity with Norway spruce. In 2006, it was reported that the fungus can also form arbutoid mycorrhiza with bearberry. Arbutoid mycorrhizal associations are variants of ectomycorrhiza found in certain plants in the Ericaceae characterised by hyphal coils in epidermal cells. The mycorrhiza formed by "L. deterrimus" on both bearberry and Norway spruce show typical features such as a hyphal mantle and a Hartig net; the distinguishing characteristic between the mycorrhizal symbioses with the different hosts is that the hyphae penetrate the epidermal cells of bearberry, although there are also some differences in the form of the Hartig net, branching pattern, and colour. Although bearberry has been shown to form mycorrhiza with a wide range of fungi both in the field and in laboratory experiments, it had never previously been known to form mycorrhiza with fungi thought to be strictly host-specific. Bearberry may function as a nurse plant to help re-establish Norway spruce in deforested areas.

The species is common in spruce-fir and spruce-moorland forests and in spruce forests and plantations. Together with spruces, the fungus is also common in different European beech and oak-European hornbeam forests, but also on the forest edges, on clearings and in clearcut meadows and even on juniper heathers and in parkland. There are scarcely any habitats where the spruce is common, while the fungus is not found there. The fungus is very common in young spruce forests that are 10 to 20 years old, where it occurs on forest path edges occasionally in masses.

The fungus probably favours calcareous soil, although it has been found on nearly every soil type. It appears on sand, peat, limestone soils, rankers and Cambisols. It endures acidic as well as alkaline and low-nutrient to relatively high-nutrient soils. Heavily eutrophic soils are inappropriate for its habitat.

The fruit bodies appear from late June to November, but usually from August to October; overwintered specimens can be found in freezing days up to early February. The fungus prefers the downs and the uplands, but is also not uncommon in lowlands.