Lactarius porninsis
Description
Lactarius porninsis is a member of the large milk-cap genus Lactarius in the order Russulales. It is found in Europe and Asia, where it grows in a mycorrhizal association with larch. It is medium-sized, orange milky cap, and it lacks most of the distinguishing features found in similar species (no pot-holes on the stem, no dramatic green staining, no excruciatingly acrid taste, no colored latex). It is associated with larches trees.
The fruit bodies of Lactarius porninsis are edible. It is one of several Lactarius species sold in rural markets in China.
The species was described by French botanist Léon Louis Rolland in 1889. Rolland collected the species in Zermatt, Switzerland. Lactarius porninae is an orthographic variant. Otto Kuntze placed it in the genus Lactifluus in 1898. The specific epithet porninsis honors Rolland's colleague M. Pornin.
Common names: Larch Milkcap.
Mushroom Identification
Ecology
Mycorrhizal with European larch; growing alone, scattered, or gregariously; summer and fall; found throughout the range of the host tree (the Alps and the Carpathians) and, reportedly, where European larch is planted as an ornamental or has been introduced.
Cap
4–8 cm; convex at first, becoming more or less flat, or shallowly depressed; sticky; bald; finely rugged; bright orange, becoming duller with age; not zoned, or zoned faintly toward the margin; the margin not lined.
Gills
Broadly attached to the stem or beginning to run down it; close; short-gills frequent; pale orange.
Stem
2–4 cm long; 1–1.5 cm thick; slightly tapered to the base; without potholes; bald; pale orange; basal mycelium white.
Flesh
Whitish to pale orange; unchanging when sliced.
Milk
White; scant; unchanging when exposed to air.
Odor and Taste
Not distinctive.
Spore Print
Reported as "cream" by Heilmann-Clausen et al. (2000) and illustrated as pale orange by Kränzlin (2005).
Microscopic Features
Spores 8–11 x 7–8 µm; ellipsoid; ornamented with amyloid warts and ridges extending up to about 0.5 µm high; connectors fairly frequent, forming wide-meshed, partially reticulate patterns. Macrocystidia narrowly fusiform; to about 50 x 7.5 µm. Lactifers very abundant in hymenial trama. Pileipellis an ixocutis; elements 2.5–5 µm wide.
Lactarius porninsis Chemistry
The fruit bodies contain fatty acid esters, which, when the fruit body is injured, are rapidly converted to the farnesane-type sesquiterpenes porninsal and porninsol. These chemicals are part of a wound-activated chemical defense system that helps protect the mushroom against parasites and predators.
Photo sources:
Photo 1 - Author: Syrio (CC BY-SA 4.0)
Photo 2 - Author: Andreas Kunze (CC BY-SA 3.0)
Photo 3 - Author: Syrio (CC BY-SA 4.0)
Photo 4 - Author: Jerzy Opioła (CC BY-SA 4.0)
