First described in 1821, it has been classified variously in the genera Psathyrella, Pseudocoprinus, Coprinarius, and Coprinus, before molecular phylogenetics reaffirmed it as a Coprinellus species in 2001.

Several other Coprinopsis species that resemble T. impatiens may be distinguished by differences in appearance, habit, or spore morphology.

The species was first described in 1821 as Agaricus impatiens by Swedish mycologist Elias Magnus Fries in his Systema Mycologicum.

[2] In 1886, Lucien Quélet transferred the species to Coprinarius[3] (a defunct genus now synonymous with Panaeolus[4]) and then to Coprinus a couple of years later in his Flore Mycologique de la France.

[10] A later (2008) study suggested, however, that these results were due to an artifact of taxon sampling—not enough species were analyzed to adequately represent the genetic variation in the genera.

The 2008 study demonstrated that Coprinellus, at that time including T. impatiens, was monophyletic, descended from a common ancestor.

[12] The cap of the fruit bodies is initially egg-shaped, then conical to convex before flattening out, reaching diameters between 1.8 to 4 cm (0.71 to 1.57 in).

[16] Tulosesus eurysporus is similar to C. disseminatus but usually grows in groups on fallen branches, and has broader spores that measure 8.3–10.3 by 6.7–8.4 μm.

[17] T. hiascens usually grows in small dense clumps, has narrower spores (typically 9–11 by 4.5–5.5 μm, and produces smaller fruit bodies.