Heliocybe sulcata

What You Should Know

Heliocybe sulcata is a rare brown mushroom, it is not often collected, and appears to be more common from the Rocky Mountains southward, into Mexico, than it is in other areas on our continent. It is a very small, gilled mushroom with a distinctively pleated cap (the cap is "sulcate," in Mycologese, resulting in the species name sulcata). Heliocybe sulcata is found on the decaying wood of hardwoods, where it is associated with brown rot of the wood.

Lentinus sulcatus, Neolentinus sulcatus, and Pleurotus sulcatus are synonyms.

Heliocybe grows on unusual substrates and places, including sun-dried wood in exposed sunny places, fence posts, railroad ties, etc. Heliocybe shares the adaptation to low-humidity, exposed places with its close relative, Neolentinus lepideus, however, that species forms larger fruiting bodies with crowded, decurrent gills. Curiously, fruiting bodies of Heliocybe can revive after desiccation, which is another way for this species to combat desiccation and extremely dry habitats. By comparing the genome of Heliocybe to that of Neolentinus as well as other brown-rot Agaricomycetes, we expect to gain an insight into the evolution of their adaptation to extreme environments and the genetic bases of agaricoid mushroom production within the Gloeophyllales.

Other names: Sunray Sawgill, Sulcate Sunhead.

Heliocybe sulcata Mushroom Identification

1. Ecology

   Saprobic on the well-decayed wood of hardwoods (especially quaking aspen); causing a brown rot; growing alone or in small groups; summer and fall; fairly widely distributed in North America.

2. Cap

   1–3 cm across; convex, becoming broadly convex; dry; ridged and grooved from the margin nearly to the center, with brownish to brown ridges and paler grooves; finely scaly with brown scales; the center more prominently scaly and darker; the margin fringed with tiny triangular points.

3. Gills

   Narrowly attached to the stem or beginning to pull away from it; nearly distant; short-gills frequent; whitish; edges serrated.

4. Stem

   10–30 mm long; 2–4 cm wide; more or less equal; dry; slightly shaggy (especially toward the base) or nearly bald; whitish to brownish; tough.

5. Flesh

   White; tough; unchanging when sliced.

6. Spore Print

   White.

7. Microscopic Features

   Spores 13–15 x 5–6 µm; subcylindric; smooth; hyaline in KOH; inamyloid. Basidia 4-spored. Hymenial cystidia fusiform; not projecting. Pileipellis a cutis of hyaline elements 2.5–2.5–7.5 µm wide; thick- or thin-walled. Hyphal system dimitic. Clamp connections are present.

Heliocybe sulcata Look-Alikes

Neolentinus species lack the conspicuous grooved cap margin, are generally larger, and have clamp connections. Lentinus tigrinus has a depressed cap center and lacks the grooved margin. Heliocybe has tougher flesh than similar-looking gilled mushrooms such as Flammulaster, Gymnopilus, and Pholiota.

Sources:

Photo 1 - Author: Landsnorkler (Creative Commons Attribution-Share Alike 3.0 Unported)

Photo 2 - Author: cbird (Creative Commons Attribution-Share Alike 3.0 Unported)