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Species Information
Summary: Subgenus Russularia. Lactarius subviscidus is typified by 1) its burnt orange color, 2) a dry to moist or thinly viscid cap, 3) a dry stem, 4) s mild odor, 5) white (rather than watery white) milk that does not turn yellow but may stain white paper yellow overnight, 6) a white to yellowish spore deposit, and 7) broadly elliptic spores with amyloid warts and ridges.
Lactarius subviscidus was cited from WA (including the holotype) and OR, (Hesler). It occurs in CA (Desjardin). There are collections from BC at the Pacific Forestry Centre and the University of British Columbia.
Cap: 1-4cm across, when young shallowly depressed with arched incurved margin, expanding to shallowly vase-shaped with wavy margin; hygrophanous, dark mahogany-red gradually becoming brick-red or paler and fading to near "onion-skin pink", first fading on margin, not zoned; bald, subviscid to thinly slimy when wet, but soon dry, smooth when moist but wrinkled when dry, (Hesler), 1-4(5)cm across, shallowly depressed becoming broadly or more deeply depressed when old; dark reddish or reddish brown to brick red or paler (pinkish) when old, not zoned usually; "smooth, viscid to thinly slimy when wet", "margin sometimes faintly striate", (Arora), 1-4(5)cm across, convex to flat, disc depressed, margin incurved to downcurved; brownish orange to brown or reddish brown, paler toward margin, azonate, similar in coloration to Lactarius subflammeus (which is noted to have much the same coloration as Lactarius substriatus); dry to moist, bald, margin even to irregularly crenate [scalloped], (Methven)
Flesh: thin; colored about as gills, (Hesler), thin, fragile; tinged cap color, (Arora), 0.2-0.4cm thick at disc; light orange, unstaining on exposure, (Methven), MILK scanty; white, unchanging, usually staining white paper yellow overnight, (Hesler), white, rather scanty, unchanging, may stain white paper yellow overnight, (Arora), white to whey-like, unchanging or slowly turning pale yellow, slowly staining field labels yellow, (Methven)
Gills: decurrent, crowded, many tiers of subgills, gills narrow, not forking appreciably; "pinkish cinnamon" or when old darker and pruinose, not discoloring where bruised, (Hesler), adnate to decurrent, close; pinkish buff to pinkish cinnamon, or darker when old, (Arora), "adnate to subdecurrent, close to subdistant, narrow", rarely forking near stem; pale orange, not staining when cut, edges colored as faces, (Methven)
Stem: 3-4cm x 0.4-0.8cm, hollow; colored as gills or nearly as red as cap; moist, non-viscid, bald, uneven, (Hesler), 2-5cm x 0.4-0.8cm, "more or less equal, usually hollow"; colored like cap or gills; smooth, not viscid, (Arora), 2-4.5(6)cm x 0.3-1cm, equal or widening slightly toward base, round in cross-section, hollow; brownish orange to brown, white to light orange tomentum at base; dry to moist, bald, not scrobiculate, (Methven)
Veil: [none]
Odor: none (Hesler), mild (Arora), not distinctive (Methven)
Microscopic spores: spores 8-10 x 7-8 microns, broadly elliptic, [amyloid] ornamentation "of ridges and some isolated warts, ridges forming a partial reticulum", prominences 0.8-1.5 microns high; basidia 4-spored, 52-57 x 10-12 microns; pleurocystidia: macrocystidia 60-75 x 7-10 microns, "narrowly fusoid to fusoid-ventricose, acuminate to the pointed apex, content granular", "pseudocystidia scattered, filamentous, flexuous", cheilocystidia scattered, about 37 x 5 microns, shape similar to macrocystidia; gill trama "of interwoven hyphae the cells of which finally become considerably inflated"; cap trama with irregular patches of sphaerocysts (+/- heteromerous); cap cuticle with a lower zone of inflated cells 2-4 thick, these often +/- isodiametric, the layer giving rise to a turf of hyphal proliferations +/- upright and branched, "this region at first embedded in slime (revived in KOH)", the elements 2-6 microns broad, in young caps the layer observed to be a lax trichoderm, (Hesler), spores 8-10 x 7-8 microns, broadly elliptic, with amyloid ridges, (Arora), spores 8-9.5 x 7-8 microns, broadly elliptic, ornamentation amyloid forming a partial reticulum 0.5-1.0 microns high; basidia 40-55 x 9.5-12 microns; macrocystidia 55-90 x 7.5-10.5 microns, fusoid to fusoid-ventricose, cheilocystidia 30-45 x 6-7.5 microns, fusoid to fusoid-ventricose; cap cuticle "a modified ixotrichodermium with a zone of inflated isodiametric or vesiculose cells, 2-4 cells thick, giving rise to a turf of upright hyphal proliferations"; stem cuticle a simple cutis with scattered projecting hyphal tips, (Methven)
Spore deposit: dull white to yellowish (Hesler), white to yellowish (Arora), white (Methven)
Habitat / Range
gregarious on very rotten conifer wood or on humus around it, (Hesler), scattered to gregarious on ground or rotten wood under conifers (Arora), scattered to gregarious in duff, in coastal coniferous-deciduous forests in association with Picea sitchensis (Sitka spruce), September to December, (Methven for CA), fall, winter
Similar Species
Lactarius luculentus and L. subflammeus have unchanging milk that does not turn white field labels yellow, and have different cap cuticle architecture. Note however is that there is some molecular evidence that L. subflammeus may be a synonym of L. subviscidus (see NOTES). Lactarius substriatus has a pale yellow spore deposit and a different cap cuticle (an ixotrichoderm arising from an interwoven layer of hyphae that are not inflated). Lactarius theiogalus has a moist cap that is ferruginous fading to orange-buff or dull rufous, and a cellular cap cuticle without a turf. Lactarius rubidus is somewhat similar but L. subviscidus has a thinly viscid cap, a mild odor, white rather than watery white milk, and broadly elliptic rather than round spores. Lactarius atrobadius has a viscid, liver-colored to blackish-red cap. Lactarius hepaticus has a moist to dry cap, and dark buttons that become chestnut brown. See also SIMILAR section of Lactarius luculentus var. laetus and Lactarius luculentus var. luculentus.
