Fruit bodies up to 35 x 20 mm, branched from the base, up to 3 mm thick at the thickest place (and therefore considered somewhat more fleshy than most taxa in the complex). Stipe up to 4.2 mm long, terete, branched almost from the base, off-white where protected, pale dull grey upward ("tilleul buff"); branches dichotomous, in 1-2 ranks, terete, "avellaneous", thickest below ultimate dichotomy; axils lunate; internodes diminishing gradually. Apices concolourous with branches, awl-shaped. Odour and taste negligible.
Macrochemical reaction: FCL = quickly black, with very little green phase.
Tramal hyphae of branches 2.5-8 µm diam., hyaline, clamped, strictly parallel, tightly packed, adherent, of relatively short cells. Subhymenium extensive, of crushed tortuous, uninflated hyphae. Hymenium thickening significantly; basidia 20-25 x 4-5 µm, cylindrical, clamped; contents minutely multiguttulate when mature; sterigmata 4, spindly, slender, erect. Spores (Figs 128,140) 4-5 x 2.9-3.6 µm (E =1.22-1.56; E^m =1.38; L^m = 4.36 µm), ovate to ellipsoid, thin-walled, hyaline, roughened; contents homogeneous to uniguttulate; hilar appendix papillate; ornamentation of thickly scattered spines and prickles of variable length.

On tree fern debris on clay bank.

Receptacula ad 35 x 20 mm, ramosa, robusta; stipite deorsum eburneo; ramis et apicibus dichotomis, avellaneis. Hyphis fibulatis; basidiis 20-25 µm longis. Sporis ovatis ad ellipsoideis, hyalinis, verrucosis, 4-5 x 2.9-3.6 µm.

COMMENTARY: The distinguishing characters of Ramariopsis avellaneo-inversa are (i) colour pattern of fruit body is the reverse of that of R. avellanea; (ii) conspicuously roughened spores; (iii) ellipsoid spores; and (iv) dramatic colour change in FCL. All but (iii) are different from those of R. avellanea, with which it would be mosr easily confused.

South Island: PSR, 19.v.82, coll. RHP, no. 43504 (holotype, PDD; isotype, TENN).