North American species of Lactarius / L. R. Hesler, Alexander H. Smith.

Subgenus Russularia

467? Lactaria beardslei Burl., Mycologia 37: 59. 1945.
Illus. Beardslee & Burlingham, I.c., fig. IB. Burlingham, I.c.,
figs. 5, 6E.
Pileus 3.5-8.5 cm broad, broadly convex becoming plane or
slightly depressed, sometimes with a small, sharp umbo, mineral brown
tone I or paler (rich cinnamon color) zoned with deeper tones, at first
white-pruinose, dull, fading and becoming azonate, slightly viscid when
wet, margin arched, finally upturned. Context near dark fawn; decidedly peppery, persistent. Latex white, unchanging, not staining, abundant; taste bitter then slowly peppery, more quickly peppery in young
specimens.
Lamellae adnate with a slight decurrent tooth, pale flesh tone 4
singly, sometimes forking near the stipe, interveined next to the pileus,
close, rather narrow, pruinose when mature.
Stipe 3-3.5 cm long, 7-12 mm thick, paler than the pileus, pruinose,
solid, nearly equal but abruptly smaller at the base.
Spore deposit fleshy white tone 3 (pale pinkish buff). Spores 7.5-9
(10) X 6-7.5(8) i, ellipsoid; plage distinct and hyaline in Melzer's; ornamentation in the form of a broken to partial reticulum of nodulose
ridges and some isolated warts in addition, prominences about 1 Au high.
Basidia 34-40 X 8-10 u, 4-spored. Pleurocystidia: macrocystidia
collapsing readily in KOH, roughly 45-67 X 6-9 pu, fusoid, pointed, more
rarely aciculate, content lightly granular; pseudocystidia filamentose,
scattered, refractive. Cheilocystidia 22-37 X 4-6 A, subfilamentose,
to subfusoid, collapsing in age. Gill trama lacking rosettes; lactifers
pallid and inconspicuous. Pileus cuticle poorly defined as a short ixolattice in KOH-soluble slime, the elements hyaline, thin-walled, septate, branching, lower cells broader than end cells which are 3-6 L wide,
the layer 45-60,L thick as revived; no cellular subcutis evident. Stipe
cortex with rosettes. Stipe cuticle of predominantly longitudinally
arranged to interwoven hyphae with many free ends projecting as
caulocystidia, no slime evident in KOH but traces seen between the
elements in mounts in Melzer's.
Habit, habitat, and distribution.-In sandy humus, under sweet
gum, collected by Burlingham 4, co-type (NY), The Black Hammock,
Oviedo, Florida, December 29, 1937.
Observations.-L. frustratus shows a strong resemblance to L. cognoscibilis but differs in its yellow staining reactions, the stipe discoloring to dark vinaceous-brown from the base upward, and the distribution. L. mutabilis is mild but is otherwise very close to L. cognoscibilis.
The relationship of these two should be studied further.