Summary:
Features include buff to yellow or brown soft-gelatinous fruitbody that is lobed to brain-like, growth on dead attached branches of dogwood and willow, often associated with Peniophora fruitbodies, and microscopic characters including round spores. "Specimens from the different substrates and regions differ only in minor respects, e.g., those on willow from British Columbia and on dogwood and witch-hazel from North Carolina are commonly red to maroon or brown rather than pale yellow to light brown as in specimens on dogwood in British Columbia." (Bandoni(5)).

Microscopic:
spores (11)12-15(16.5) x 10-12(14) microns, mostly bullate [probably bulliform], some nearly round, "the apiculus up to 3.5 microns broad basally, 2.5 microns high, and is placed midway on the flattened adaxial surface in the bullate forms", germination is by repetition or budding; probasidia 20-30.5 x (15)18-24(30.5) microns, predominantly spherical or nearly spherical, a few obovoid or ellipsoid, 4-celled, epibasidia "35-100 x 3-5 microns, expanded to 5-10 microns distally for approximately 20-30(50) microns of the length, thin-walled, retraction septa often present, collapsing when empty"; hymenium "amphigenous, the basidia scattered in a zone extending from 20-250 microns deep, exceeded by fertile hyphae", both these and the basidia with an abundance of droplets; context hyphae in fertile lobes 1.5-4 microns wide, the walls not notably thickened, haustorial branches absent in these context hyphae; subcortical primordium flattened beneath the bark, in section hyphae compact, mostly 4-6 microns wide, a few inflated up to 15 microns, the walls thickened to 1.5-3(5) microns and often visibly layered, clamp connections abundant, mostly of medallion type, haustorial branches present, "vesicles present, often unevenly distributed, aggregated in some spots and absent elsewhere, 11.5-44.5 x 8-15(-26) microns, the walls of some up to 3.5 microns thick"; haploid phase a yeast

Notes:
Tremella mesenterella is found in BC, ON, GA, and NC. (Bandoni(5)).