176 NORTH AMERICAN FLORA LVoLUME 9 
I. Piperatae. Pileus without a pellicle, never viscid, glabrous or tomentose ; margin 
involute at first varying from naked to densely tomentose: context firm; lamellae neither 
becoming darker nor pruinose with age; latex very acrid, white, unchanging or in some 
species staining the lamellae yellow or glaucous-green in drying. 
1. Lactaria piperata (L,.) Pers. Tent. Disp. Fung. 64. 1797. 
Agaricus piperaius I,. Sp. Pl. 1173. 1753. 
Agaricus Listeri With. Brit. Pl. ed. 2.3: 288. 1792. 
Pileus fleshy, convex-umbilicate, at length infundibuliform, 4-12 cm. or more in diam- 
eter ; surface white, azonate, dry, glabrous; margin involute at first and naked, at length 
uplifted : context compact, white, unchanging or becoming sordid, edible; latex white, 
unchanging, very acrid, abundant ; lamellae white or creamy-white, forking dichotomously, 
close, more or less decurrent, arcuate at first, then extending upwards, only about 2 mm. 
broad ; stipe white, equal, dry, often pruinose, solid and firm, 2-8 cm. long, up to 2 cm. 
thick: spores white, subglobose, nearly smooth, 8-9 in diameter. 
TYPE LOCALITY: Sweden. 
HasitatT: Oak woods or groves. 
DISTRIBUTION : Temperate North America and Europe. 
ILLUSTRATIONS: Atk. Stud. Am. Fungi f. 179; Barla, Champ. Nice p/. 22, f. 1-5; Bull. Herb. 
Fr. pl. 200 (as Avaricus acris) ; Cooke, Brit. Fungi pl. 979, Fries, Sv. Aetl. Svamp. p/. 27; Lanzi, 
Funghi Mang. p/. 54, f. 2, a, 6,¢c; Mclly. Am, Fungi pl. 41, 7.1, Schaeff. Fung. Bavar. p/. 83 (as 
Agaricus amarus) ; Bull. Conn. Geol. Nat. Hist. Surv. 3: pl. 9. 
EXSICCATI: Burl. Lact. N. Am. 7; Rav. Fungi Car. 2: 5 p. £.; Roum. Fungi Gall. 389. 
2. Lactaria pergamena (Sw.) Fries, Epicr. Myc. 340. 1838. 
Agaricus pergamenus Sw. Sv. Vet.-Akad. Nya Handl. 30: 90. 1809. 
Pileus fleshy, thin, convex to plane or depressed, often irregular and eccentric, and 
usually flexuous, 4-11 cm. broad; surface white to creamy-white when old, azonate, dry, 
glabrous, minutely wrinkled ; margin becoming extended, naked: context pliant, white, 
edible; latex white, unchanging or sometimes drying sulphury-white, abundant, acrid ; 
lamellae white then straw-colored, very close, thin, forking, adnate, horizontal, very nar- 
row, 1 mm. broad; stipe white, equal or tapering downwards, glabrous, smooth, stuffed, 
but firm: spores white, minutely echinulate, elliptic, 6X 84. 
TYPE LOCALITY: Sweden. 
HaBitTatT: Oak woods. 
DISTRIBUTION : United States east of the Mississippi; also in Europe. 
ILLUSTRATIONS: Batsch, Elench. Fung. pl. 13, 7.59, a, b,c (as Agaricus piperatus); Cooke, 
Brit. Fungi p/. 978; Gill. Champ. Fr. pl. 152 (389) ;1 Krombh. Abbild. p/. 57, f. 1-6; Lucand, 
Champ. Fr. pl. #2. 
ExsiccaTi: Burl. Lact. N. Am. 2. 
3. Lactaria glaucescens Crossl. Naturalist 1900: 5. 1900. 
Pileus fleshy, convex-umbilicate, then infundibuliform, 4-9 cm. broad; surface white, 
becoming stained or spotted with yellowish-buff, dry, glabrous; margin involute at first, 
even, naked: context firm, thick, whitish, staining glaucous-green where the latex dries ; 
latex white, drying glaucous-green on the flesh and lamellae, very acrid, abundant ; lamellae 
maize-yellow at first, becoming white as the pileus expands, staining glaucous-green where 
the latex dries, forked, very close, adnate, 1-1.5 mm. wide; stipe white, tapering down- 
wards or sometimes nearly equal, solid, firm, 3-9 cm. long, 1.5 cm. thick at the base to 2 
cm. thick at the apex: spores white, globose, minutely and sparsely echinulate, 5.5-7 k in 
diameter ; cystidia terete-clavate, 40-60 * 7-8 y. 
TYPE LOCALITY: West Yorkshire, England. 
HaBitatT: On the ground in sandy loam or in vegetable soil, oak-chestnut woods. 
DISTRIBUTION : North Carolina, 1000 meters elevation ; also in England. 
ILLUSTRATIONS : Mem. Torrey Club 14: 25. 7.1; Naturalist 1900: 10. 7 1-3. 
EXSICCATL: Burl. Lact. N. Am. 5. 
1The plates in Gillet, Champ. Fr. were renumbered in 1890 and again upon the com- 
pletion of the work. In citation the original numbers are followed by the numbers occur- 
ring in the subsequent revisions. 
