Pileus (Cap): 1.2 -2.5 cm broad, conic to convex at first bu then becoming hemispheric and expanding to broadly convex to nearly plane. Surface smooth moist to viscid when wet, soon drying, and often cracking with irregular horizontal fissures. Young primordia are chocolate brown to red in color, fading to lighter brownish yellow-red in age. Flesh light yellow, pale becoming blue where damaged or cut. Fine filaments are visible on the stipe showing the remnants of the veil. Margin is incurved when young, expanding in age and often becoming irregular in shape.
Lamellae (Gills): Pallid at first, then becoming grayish black to black, with mottled sections where the spores have matured in different areas on the gill surface. Gills are intermediate, attachment is ascending, uncinate, with several tiers of intermediate gills, ranging from three to four separate tiers.
Stipe (Stem): (30) 80-100 mm long by 1.5-3 mm thick. Attached centrally and swelling up from the base, difficult to separate the cap and stem without causing gill fragments to form. Striations run along the stipe and especially at the apex where the annular zone can be seen. Whitish to cream in color and rapidly turning blue where handled.
Microscopic features: 11-13 microns, black in deposit, somewhat transparent under magnification. 4-spored with the occasional 2-spored basidium. Large centrally located germ pore is visible, showing a dark purple brown color under the microscope. Pleurocystidia present, fusoid -ventricose with a sharp elongated apex, measuring 48-60 x 13-19 um long. Cheilocystidia also present, measuring 12-14 x 2.5-5um, appearing much like the pleurocystidia in form.
Season: In the spring or during the rainy seasons.
Habitat and Distribution: Manure and enriched soils Preferably the dung of buffalo and cattle, was first described from Cambodia. Thought to be more widespread through the asian subtropics. Was found in 1993 by Merlin and Allen at kahalu'u O'ahu, Hawaii. FlickrMO Occurrence Map
Growth Habit: Grows scattered to gregariously
Bruising: Bluing strongly where handled.
Dosage: 4 to 7 to 10 fresh mushrooms, 1-2 dried grams.
Other Notes: Highly domesticated and stable with low genetic variability. Previously considered a strain of Panaeolus tropicalis, this collection is better considered as the similar P. cambodginiensis. The documentation of the various Panaeolus species contains conflicting information which initially misled staff on this particular collection. P. tropicalis and P. cambodginiensis have similar sized spores and are easily confused.