Part 64

Spores: very long, dark brown under the microscope, smooth, ellipsoid with large germ-pore and about 18 × 10 µm in size (17-20 × 9-10 µm).

Facial cystidia: spindle-shaped, thin-walled and filled with amorphous contents which become yellow in solutions containing ammonia.

Marginal cystidia: spindle-shaped or flask-shaped, numerous, thin-walled and typically yellowing as above.

General Information: ‘Semiglobata’ means hemispherical and refers to the shape of the cap of S. semiglobata; it is a very variable fungus in both size of the cap and the prominence of the ring. The Dung-roundhead grows only on dung which is acidic in its soil status, whilst Panaeolus semiovatus (Fries) Lundell next described (p. 210) grows on slightly to distinctly base-rich dung. This may explain why in Britain the Dung-roundhead is the commoner of the two species. However, P. semiovatus was formerly placed in the genus Stropharia because of its blackish spores and distinct ring. The spores of Stropharia in the mass are violaceous black whilst those of P. semiovatus are brownish black. Under the microscope they are also differently coloured and have different chemical compositions as their reaction with dilute solutions of ammonia shows; the spores of the first species turn purplish olive in ammonia and those of the second species become very dark brown.

Illustrations: F 33^{b}; Hvass 171; LH 153; NB 31⁵; WD 75³.

Mottle-gills--on dung from Spring until Autumn.

~Panaeolus semiovatus~ (Fries) Lundell

Cap: width 20-70 mm. Stem: width 5-10 mm; length 80-160 mm.

Description:

Cap: oval or bell-shaped, not expanding, dingy whitish or pale clay colour, smooth, slimy when moist, but soon drying and then becoming shiny, often wrinkled and cracked, and ornamented with fragments of veil at the margin.

Stem: dull, straight, rather rigid, tapering upwards, white, and striate at apex above a whitish erect and membranous, often collapsing, ring; yellowish below the ring and whitish and cottony at the slightly swollen base.

Gills: adnate, greyish then black, mottled and crowded.

Flesh: whitish or pale ochre.

Spore-print: black.

Spores: very long, very dark brown under the microscope with large obvious germ-pore and 18 × 10 µm (16-20 × 9-11 µm) in size.

Facial cystidia: flask-shaped and with amorphous contents.

Marginal cystidia: numerous, flask-shaped.

~Panaeolus sphinctrinus~ (Fries) Quélet

Cap: width 15-35 mm. Stem: width 3-6 mm; length 60-95 mm.

Description:

Cap: bell-shaped, hardly expanding, expallent, dark grey to olivaceous black, much paler when dry and zoned when half dry; margin ornamented with a white fringe of veil fragments.

Stem: long, slender, straight, rather rigid but fragile, grey and completely powdered with white.

Gills: adnate, crowded and grey then blackened, mottled throughout except at the white fringed edge.

Flesh: reddish brown.

Spore-print: black.

Spores: long, very dark brown under the microscope, broadly lemon-shaped with large germ-pore, smooth and 14-15 × 9-10 µm in size (14-19 × 8-10 × 10-12 µm).

Facial cystidia: absent.

Marginal cystidia: numerous, cylindrical, flexuous and hyaline.