Table 2. Key to the laccate Ganoderma species in the United States.

Members of the laccate Ganoderma are have shiny or varnished pilei, and can be sessile, stipitate or pseudostipitate. The context tissue of the laccate Ganoderma species is corky to felty in texture, and generally white, cream to light buff, or cinnamon brown. Context tissue can have melanoid/resinous bands and/or concentric growth zones present or absent. Some taxa produce contextual chlamydospores that are double-walled, hyaline to pigmented, and ornamented or smooth. The basidiospores are double-walled, golden-brown in 5% KOH, echinulated and generally broadly ovoid to elliptical with a truncated apex at maturity. Ecologically these species are associated with a white rot type decay typically on hardwood, coniferous, or palm substrates. Disclaimer: This key is solely based on morphology, host preference and known geographic distributions of the laccate Gaonderma present in the U.S. based on this study.

1	Context tissue white when fresh	2
1	Context tissue not as above	4
2	Large basidiospores measuring on average 16.1 (14.6–17.3) x 10.4 (9.5–11.3) μm; fruiting body spongy, light-weight, shiny, and yellow	T. colossus (syn. = G. colossus)
2	Basidiospores smaller than above	3
3	Found on conifers in the Pacific Northwest, with basidiospores measuring on average 12.9 (11.6–14.9) x 8.0 (6.7–9.3) μm	G. oregonense
3	Found on conifers, predominately Tsuga canadensis, in the boreal hemlock forests of the eastern U.S. with basidiospores measuring on average 9.9 (8.9–11.5) x 6.5 (5.2–7.7) μm	G. tsugae
4	Context tissue cream to buff	5
4	Context tissue dark brown (cinnamon brown)	11
5	Shiny, melanoid deposits present in the context tissue	6
5	Melanoid bands absent, concentric growth zones sometimes present in the context tissue	7
6	Typically a laterally stipitate fruiting body, fruiting on hardwoods in the eastern U.S with basidiospores on average measuring 10.6 (8.3–12.1) x 6.4 (5.4–7.5), and growing somewhat rapidly (approximately 6 mm/day) on malt extract agar	G. curtisii
6	Typically a laterally stipitate fruiting body, fruiting on pines in the southeastern U.S with basidiospores on average measuring 10.8 (9.5–11.5) x 6.8 (6.4–7.3), and growing slowly (less than 3 mm/day) as a dikaryotic isolate on malt extract agar	G. curtisii f.sp. meredithiae
7	Typically sessile fruiting body morphology, or if stipe present, considered a pseudostipe, where the length of the stipe is less than the width of the pileus	8
7	Typically laterally stipitate fruiting body with no melanoid bands and concentric growth zones sometimes present in the context tissue	10
8	Found in association with hardwoods in the western United States, often with conspicuous concentric growth zones present in the context tissue	G. polychromum
8	Found in the eastern United States	9
9	Pigmented, double-walled globose to ovoid chlamydospores found in the context tissue, and restricted to tropical locations	G. cf. weberianum
9	Widely distributed East of the Rocky Mountains predominately associating with hardwood trees/substrates, basidiospores measuring on average 11.4 (9.7–14.0) x 6.6 (5.2–8.4) μm	G. sessile
10	Concentric growth zones absent from the context tissue, present in the southeastern U.S., and basidiospores measuring on average 11.2 (9.1–13.6) x 5.2 (4.2–6.8) μm	G. ravenelii
10	Concentric growth zones present in the context tissue, and restricted to isolated populations in northern Utah and northern California	G. lucidum
11	Basidiospores elongated measuring on average 11.8 (10.3–13.7) x 5.9 (5.0–6.0) μm, and associated with monocot trees/substrates, typically palms	G. zonatum
11	Not as above	12
12	Typically producing a central pseudostipe that is often dark red to black, associated with hardwood trees/substrates, concentric growth zones and melanoid deposits present in context tissue, and hymenium on average having 5–6 pores/mm	G. martinicense
12	Sessile fruiting body that is orange to red when active, and dark red when mature, concentric growth zones and shiny, resinous deposits present in the context, hymenium on average having 4–7 pores/mm, restricted to tropical locations, and basidiospores measuring on average 10.5 (9.2–12.0) x 7.3 (6.2–8.6) μm	G. tuberculosum