Appearance''A. praecox'' belongs to a group of species which are difficult to distinguish consistently. The following description combines several references.
⤷ Cap: up to 8 cm, convex, smooth, beige when dry and yellowish brown when imbued with moisture. Veil remnants are often visible around the rim.
⤷ Gills: Initially whitish, later dark brown.
⤷ Stem: Pale; 4 to 7 cm ; quite thick with a fragile ring. Often with mycelial cords at the base.
⤷ Odor and taste: Floury. Taste may be bitter.
⤷ Spores: 8 - 10 x 5 - 7 µm, ellipsoid, dark brown .
⤷ Habitat: Gregarious in grass or on wood debris in woods, gardens, or other contexts. Like other ''Agrocybes'', it is a saprophyte.
⤷ Season: Often observed in spring, but can also occur in summer and autumn.
NamingThe mushroom was first described by Persoon in 1800 as ''Agaricus praecox''. In 1889 Fayod devised the new genus ''Agrocybe'' and made ''A. praecox'' the type species.
The Latin epithet ''praecox'' "early" is related to the word "precocious" and refers to the fact that this species often appears early in the year.
A 1990 study by Timothy Flynn and O. K. Miller finds that ''A. praecox'' is one of four species which are indistinguishable using superficial characteristics but which can be separated through their habitat and location. If this proposal is accepted, the cluster consists of ''A. molesta'' and three other species which do not yet have proper names, but which are referred to as "Flynn & Miller Species I - III". The three provisional species correspond to the older names ''A. acericola'', ''A. elatella'', ''A. praecox'', and ''A. sphaleromorpha'' combined; and their synonyms. According to the traditional system, various detailed morphological characteristics can be used to choose between the species, but such is variation amongst individuals that it is difficult to achieve a consistent identification in this way.
The following table summarizes the names of species which are closely related to ''A. praecox''. Note that Index Fungorum has been used as a reference throughout.
!Species, author & date
!Description & References
!Relation to ''A. praecox''
|''Agrocybe acericola'' Singer
|Found on woody debris in hardwood forests, cap yellow-brown, often veined or wrinkled in the centre. May be the same as Flynn & Miller Species III.
|Not distinguished from ''A. praecox'' in Funga Nordica.
|''Agrocybe dura'' Singer
|This is a synonym of ''A. molesta'' .
|See ''A. molesta''.
|''Agrocybe elatella'' Vesterh.
|Grows amongst moss in marshes and fens.
|Smaller with more slender stipe, hygrophanous, stem not bulbous.
|''Agrocybe gibberosa'' Fayod
|Synonym of ''A. praecox''.
|''Agrocybe molesta'' Singer
|This is certainly a distinct species which grows in grass, but according to Flynn & Miller it is part of the ''A. praecox'' complex, and the only species which gets its nutrition from grass .
|It is bigger and fleshier than ''A. praecox'', the cap surface develops superficial cracks and the spores are somewhat bigger.
|''Agrocybe paludosa'' Kühner & Romagn.
|This is a synonym of ''A. elatella''.
|See ''A. elatella''.
|''Agrocybe sphaleromorpha'' Fayod
|Not distinguished from ''A. praecox'' in Funga Nordica
|Smaller, having a bulbous stipe, found in pasture.
|Flynn & Miller Species I
|Temporary name for first proposed new species.
|Grows in gardens on wood chip mulch.
|Flynn & Miller Species II
|Temporary name for second proposed new species.
|Grows on wood litter in coniferous or aspen forests in western North America.
|Flynn & Miller Species III
|Temporary name for third proposed new species.
|Grows on wood litter in broadleaf forests in eastern North America. May be the same as ''A. acericola''.
Some text fragments are auto parsed from Wikipedia.