Plants not gelatinous; basidia continuous.  1
Plants gelatinous or sub-gelatinous, basidia forked, or divided longitudinally or transversely.  4
1—Hymenium uneven, i. e., in the form of radiating plates, or folds; or a honey-combed surface, or reticulate, warty, spiny, etc.  2
Hymenium smooth (not as in B, though it may be convolute and irregular, or ribbed, or veined).  3
2—Hymenium usually on the under side, in the form of radiating plates, or strong folds. The genus Phlebia in the Hydnaceae has the hymenium on smooth, somewhat radiating veins which are interrupted and irregular. One exotic genus has the hymenium on numerous irregular obtuse lobes (Rhacophyllus).Agaricaceæ.17
Hymenium usually below (or on the outer surface when the plant is spread over the substratum), honey-combed, porous, tubulose, or reticulate; in one genus with short, concentric plates.Polyporaceæ.171
Hymenium usually below (or on the outer surface when the plant is spread over the substratum), warted, tuberculate, or with stout, spinous processes; or with interrupted vein-like folds in resupinate forms.Hydnaceæ.195
3—Plants somewhat corky or membranaceous, more or less expanded; hymenium on the under surface (upper surface sterile), or on the outer or exposed surface when the plant is spread over the substratum (margin may then sometimes be free, but upper surface, i. e., that toward the substratum, sterile). (Minute slender spines are sometimes intermingled with the elements of the hymenium, and should not be mistaken for the stouter spinous processes of the Hydnaceæ).Thelephoraceæ.208
Plants more or less fleshy, upright (never spread over the surface of the substratum), simple or branched. Hymenium covering both sides and the upper surface.Clavariaceæ.200
4—Basidia forked or longitudinally divided; or if continuous then globose, or bearing numerous spores; or if the plant is leathery, membranous, or floccose, then basidia as described. Hymenium covering the entire free surface or confined to one portion; smooth, gyrose, folded or lobed; or hymenium lamellate, porous, reticulate or toothed forms which are gelatinous and provided with continuous basidia may be sought here.Tremellineæ.204

FAMILY AGARICACEAE.

Pileus more or less expanded, convex, bell-shaped; stipe central or nearly so; or the point of attachment lateral, when the stipe may be short or the pileus sessile and shelving. Fruiting surface usually on the under side and exposed toward the earth, lamellate, or prominently folded or veined. Lamellæ or gills radiating from the point of attachment of the pileus with the stipe or with the substratum in the sessile forms; lamellæ simple or branched, rarely anastomosing behind, clothed externally on both surfaces with the basidia, each of which bears four spores (rarely two), cystidia often present.

Key to the North American genera.

THE WHITE-SPORED AGARICS.

(Sometimes there is a faint tinge of pink or lilac when the spores are in bulk, but the color is not seen under the microscope.)

Plants soft, fleshy or nearly so, usually soon decaying; dried plants do not revive well when moistened.  1 
Plants tough, either fleshy or gelatinous, membranaceous, corky or woody, persistent, reviving when moistened.13 
1—Gills acute on the edge.  2 
Edge of the gills obtuse, or gills fold-like, or vein-like, but prominent.12 
2—Trama of the pileus of interwoven threads, not vesiculose.  3 
Trama of the pileus vesiculose, plants rigid but quite fragile.11 
3—Gills thin, not much broadened toward the pileus.  4 
Gills broadened toward the pileus, of waxy consistency.Hygrophorus.110
4—Stipe central or sub-central. (Some species of Pleurotus are sub-central, but the gills are usually not decurrent.)  5 
Stipe on one side of the pileus, or none, rarely with the stipe sub-central. (Some species of Clitocybe are sub-central.)Pleurotus.102
5—Stipe fleshy, pileus easily separating from the stipe, gills usually free.  6 
Stipe fleshy or fibrous and elastic, pileus confluent with the stipe and of the same texture.  7 
Stipe cartilaginous, pileus confluent with the stipe, but of a different texture.  9 
6—Volva and annulus present on the stipe.Amanita.52
Volva present, annulus wanting.Amanitopsis.74
Volva wanting, annulus present.Lepiota.77
7—Annulus and volva wanting.  8 
Annulus usually present (sometimes vague), volva wanting, gills attached to the stipe.Armillaria.83
8—Gills sinuate.Tricholoma.87
Gills decurrent, not sinuate.Clitocybe.89
9—Gills decurrent, pileus umbilicate.Omphalia.100
Gills not decurrent.10 
10—Margin of pileus at first involute, pileus flat or nearly so, somewhat fleshy (some plants rather tough and tending toward the consistency of Marasmius).Collybia.92
Margin of the pileus at first straight, pileus slightly bell-shaped, thin.Mycena.93
Gills usually free, pileus deeply plicate so that the gills are split where they are attached to the pileus, pileus membranaceous, very tender but not diffluent.Hiatula. 
11—Plants where bruised exuding a milky or colored juice.Lactarius.114
Plants not exuding a juice where bruised.Russula.125
12—Gills decurrent, dichotomous, edge blunt.Cantharellus.128
Gills not decurrent, plants parasitic on other mushrooms.Nyctalis. 
13—Edge of gills not split into two laminæ.14 
Edge of gills split into two laminæ and revolute.Schizophyllum.136
14—Plants leathery, either fleshy, membraneous, or gelatinous.15 
Plants corky or woody (placed by some in Polyporaceæ).Lenzites. 
15—Stipe separate from the pileus (hymenophore), easily separating.16 
Stipe continuous with hymenophore.17 
16—Plants tough and fleshy, membranaceous or leathery.Marasmius.130
Plants gelatinous and leathery.Heliomyces. 
17—Edge of the gills acute.18 
Edge of the gills obtuse.19 
18—Edge of gills usually serrate.Lentinus.134
Edge of gills entire.Panus.134
19—Gills dichotomous.Xerotus. 
Gills fold-like, irregular.Trogia.137

There are only a few rare species of Hiatula, Nyctalis, Heliomyces and Xerotus in the United States. None are here described.

THE OCHRE-SPORED AGARICS.

(The spores are yellowish brown or rusty brown.)

Gills not separating readily from  1 
Gills sometimes separating readily from the pileus, forked or anastomosing at the base, or connected with vein-like reticulations.Paxillus.165
1—Universal veil not arachnoid (i. e., not cobwebby).  2 
Universal veil arachnoid, distinct from the cuticle of the pileus, gills powdery from the spores.Cortinarius.161
2—Stipe central.  3 
Stipe eccentric or none.Crepidotus.159
3—Volva or annulus present on stipe.  4 
Volva and annulus wanting.  5 
4—Stipe with an annulus.Pholiota.150
Stipe with a volva. Locellina (not reported in U. S.).
5—Gills free from the stem.Pluteolus.
Gills attached.  6 
6—Gills not dissolving nor becoming powdery.  7 
Gills dissolving into a gelatinous or powdery condition, not diffluent as in Coprinus.Bolbitius.163
7—Stipe fleshy.  8 
Stipe cartilaginous or sub-cartilaginous.10 
8—Gills somewhat sinuate.  9 
Gills adnate or decurrent.Flammula.156
9—Cuticle of the pileus silky or bearing fibrils.Inocybe.158
Cuticle of pileus smooth, viscid.Hebeloma.157
10—Gills decurrent.Tubaria.159
Gills not decurrent.11 
11—Margin of pileus inflexed.Naucoria.153
Margin of pileus straight, from the first.Galera.155

No species of Pluteolus are here described.

THE ROSY-SPORED AGARICS.

(The spores are rose color, pink, flesh or salmon color.)

Stipe central.  1 
Stipe eccentric or none and pileus lateral.Claudopus.149
1—Pileus easily separating from the stipe, gills free.  2 
Pileus confluent with the stipe and of the same texture, gills attached, in some becoming almost free.  3 
2—Volva present and distinct, annulus wanting.Volvaria.140
Volva and annulus wanting.Pluteus.138
3—Stipe fleshy to fibrous, margin of pileus at first incurved.  4 
Stipe cartilaginous.  5 
4—Gills sinuate.Entoloma.143
Gills decurrent.Clitopilus.142
5—Gills not decurrent (or if so only by a minute tooth), easily separating from the stipe.  6 
Gills decurrent, pileus umbilicate.Eccilia.148
6—Pileus slightly convex, margin at first incurved.Leptonia.147
Pileus bell-shaped, margin at first straight and pressed close against the stipe.Nolanea. 

No species of Nolanea are described here.

THE BROWN-SPORED AGARICS.

(The spores are dark brown or purplish brown.)

Pileus easily separating from the stem; gills usually free.  1 
Pileus continuous with the stem; gills attached.  2 
1—Volva wanting, annulus present. (Psalliota Fr.)Agaricus.18
Volva present, annulus wanting.Chitonia. 
Volva and annulus wanting.Pilosace. 
2—Veil present.  3 
Veil wanting or obsolete.  4 
3—Annulus present, gills attached.Stropharia.31
Annulus wanting, veil remaining attached to margin of pileus.Hypholoma.26
4—Stipe tenacious, margin of pileus first incurved.  5 
Stipe fragile, margin of pileus at first straight.Psathyra. 
5—Gills sub-triangularly decurrent.Deconica. 
Gills not decurrent.Psilocybe. 

But few species of Psathyra, Deconica, Chitonia and Pilosace are noted from the United States. None are here described.

THE BLACK-SPORED AGARICS.

Pileus present to which the gills are attached.  1 
Pileus wanting, gills attached to a disk at apex of stem from which they radiate.Montagnites.[G] 
1—Gills more or less deliquescing, or pileus thin, membranous and splitting between the laminæ of the gills and becoming more or less plicate.Coprinus.32
Gills not deliquescing, etc.  2 
2—Spores globose, ovoid.  3 
Spores elongate, fusiform (in some species brown), plants with a slimy envelope.Gomphidius.49
3—Pileus somewhat fleshy, not striate, projecting beyond the gills at the margin; gills variegated in color from groups of dark spores on the surface.  4 
Pileus somewhat fleshy, margin striate, gills not variegated.Psathyrella.48
4—Annulus wanting, but veil often present.Panæolus.45
Annulus wanting, veil appendiculate on margin of cap.Chalymotta.48
Annulus present.Anellaria. 

GLOSSARY OF THE MORE TECHNICAL TERMS USED IN THIS WORK.

Abbreviations:

Adnate, said of the gills when they are attached squarely, or broadly, to the stem.

Adnexed, said of gills when they are attached only slightly or only by the upper angle of the stem.

Anastomose, running together in a net-like manner.

Annulus, the ring or collar around the stem formed from the inner or partial veil.

Appendiculate, said of the veil when it clings in fragments to the margin of the pileus.

Arachnoid, said of the veil when it is cobwebby, that is, formed of loose threads.

Ascus, the club-shaped body which bears the spores inside (characteristic of the Ascomycetes).

Basidium (pl. basidia) the club-shaped body which bears the spores in the Basidiomycetes. These stand parallel, and together make up the entire or large part of the hymenium or fruiting surface which covers the gills, etc. Paraphyses (sterile cells) and sometimes cystidia (longer sterile cells) or spines are intermingled with the basidia.

Bulbous, said of the enlarged lower end of the stem in some mushrooms.

Circumscissile, splitting transversely across the middle, used to indicate one of the ways in which the volva ruptures.

Cortina, a cobwebby veil.

Cuticle, the skin-like layer on the outside of the pileus.

Decurrent, said of the gills when they extend downward on the stem.

Diffluent, said of the gills when they dissolve into a fluid.

Dimidiate, halved, said of a sessile pileus semi-circular in form and attached by the plane edge directly to the wood.

Echinulate, term applied to minute spinous processes, on the spores for example.

Eccentric, said of a stem when it is attached to some other point than the center of the pileus.

Fimbriate, in the form of a delicate fringe.

Fistulose, becoming hollow.

Floccose, term applied to indicate delicate and soft threads, cottony extensions from the surface of any part of the mushroom.

Flocculose, minutely floccose.

Fugacious, disappearing.

Fuliginous (or fuligineous), dark brown, sooty or smoky.

Fulvous, tawny, reddish yellow.

Fusiform, spindle-shaped.

Fusoid, like a spindle.

Furfuraceous, with numerous minute scales.

Gleba, the chambered tissue forming the hymenium (fruiting surface) in the puff-balls and their allies.

Hygrophanous, appearing to be water soaked.

Hymenium, the fruiting surface of the mushrooms and other fungi.

Hymenomycetes, the subdivision of the Basidiomycetes in which the fruiting surface is exposed before the spores are ripe.

Hymenophore, the portion of the fruit body which bears the hymenium.

Hypha (pl. hyphæ), a single mycelium thread.

Imbricate, overlapping like the shingles on a roof.

Involute, folded or rolled inward.

Lamella (pl. lamellæ), the gills of the mushroom.

Mycelium, the vegetative or growing portion of the mushrooms, and other fungi, made up of several or many threads.

Ocreate, applied to the volva where it fits the lower part of the stem, as a stocking does the leg.

Pectinate, like the teeth of a comb.

Peridium, the wall of the puff-balls, etc.

Pileus (pl. pilei), the cap of the mushroom.

Plicate, plaited, or folded like a fan.

Punctate, with minute points.

Pulverulent, with a minute powdery substance.

Repand, wavy.

Resupinate, spread over the matrix, the fruiting surface external and the pileus next the wood.

Revolute, rolled backward.

Rugose, wrinkled.

Rugulose, with minute wrinkles.

Saprophytic, growing on dead organic matter.

Sessile, where the pileus is attached directly to the matrix without any stem.

Sinuate, said of the gills when they are notched at their junction with the stem.

Stipe, the stem.

Sulcate, furrowed.

Squamulose, with minute scales.

Squarrose, with prominent reflexed scales.

Tomentose, with a dense, matted, hairy or woolly surface.

Trama, the interior portion of the gills or pileus.

Umbo, with a prominent boss or elevation, in the center of the pileus.

Umbilicate, with a minute abrupt depression in the center of the cap.

Veil, a layer of threads extending from the margin of the cap to the stem (partial veil or marginal veil). A universal veil envelops the entire plant.

Veins, elevated lines or folds running over the surface of the lamellæ in some species, and often connected so as to form reticulations.

Ventricose, enlarged or broadened at the middle, bellied.

Vesiculose, full of small rounded vesicles, as the trama of the pileus of a Russula.

Volva, a wrapper or envelope, which in the young stage completely surrounds the plant, same as universal veil. At maturity of the plant it may be left in the form of a cup at the base of the stem, or broken up into fragments and distributed over the cap and base of the stem.

FOOTNOTES:

[F] The sub-class Ascomycetes includes the morels, helvellas, cup fungi, etc., and many microscopic forms, in which the spores are borne inside a club-shaped body, the ascus. Only a few of the genera are described in this book, and the technical diagnosis will be omitted. See page 216.

[G] One American species in Texas.

INDEX OF GENERA, AND ILLUSTRATIONS.

Note.—In this index the generic and specific names have been divided into syllables, and the place of the primary accent has been indicated, with the single object of securing a uniform pronunciation in accordance with the established rules of English orthoepy.