Cap: bell-shaped but rapidly expanding to become plane, honey-yellow with a greyish green tint, slightly striate at the margin and also with a few remnants of a fibrillose veil when very young, but these are soon lost.
Stem: slender, smooth, whitish at the apex and yellow-brown or honey-yellow below.
Gills: adnate and distant, pale ochraceous honey-yellow then lilaceous grey and finally sepia.
Flesh: yellowish in the cap, red-brown in the stem and lacking a distinct smell.
Spore-print: purplish brown.
Spores: long, ellipsoid, fairly thick-walled, olivaceous brown under the microscope and with a small germ-pore, smooth and 10-12 × 6-7 µm in size.
Marginal cystidia: flask-shaped and hyaline.
Facial cystidia: flask-shaped with contents which turn yellowish in solutions containing ammonia.
General Information: This fungus which appears from early summer to late autumn is recognised by the almost uniform ochraceous colour with hint of olive and its habit of growing in troops. The word elongatum means elongated and refers to the shape of the stem which pushes up through the Sphagnum and in order to disperse its spores it must elongate so that it just pushes up above the bog-surface. H. polytrichi is closely related to H. elongatum but has a paler cap and stem and it grows in moss, particularly Polytrichum in woodlands; the spores of H. polytrichi are paler, slightly narrower and slightly thinner, but they have a much more distinct germ-pore.
Both the above species have been formerly placed in Psilocybe, but they are more correctly classified in Hypholoma along with the sulphur-tuft fungus (see [p. 64]) because of the cortina-like veil and specialised facial cystidia.