The North American Species of Pholiota

172. Pholiota spumosa (Fr.) Singer Lilloa 22: 517. 1951.

Agaricus spumosus Fries, Syst. Myc. 1: 252. 1821.
Flammula spumosa (Fr.) Kummer, Der Führer in die Pilzkunde, p. 81. 1871.
Dryophila spumosa (Fr.) Quélet, Enchir. Fung. p. 70. 1886.

Illustrations: Text figs. 377-380; pl. 77-78.

Pileus caespitose to gregarious, (2) 3-6 cm broad, at first broadly and obtusely conic to convex, becoming expanded-plane, with or without an umbo, or at times with a prominent conic umbo, when young "Isabella-color" over all, or the margin "olive-ocher," "ecru-olive," darker and more brownish toward the "tawny" to "ochraceous-tawny" or "buckthorn-brown" disc, at maturity the marginal portion yellowish, often with a greenish tint, glutinous or viscid, glabrous but appearing fibrillose-streaked, sometimes the center roughened by the drying gluten. Context yellow, sometimes a watery "bright green-yellow," soft; odor and taste mild.

Lamellae adnate to adnexed, or with a decurrent tooth, at first "sulphur-yellow" to "citron-yellow," "massicot-yellow," or "pale greenish-yellow," becoming tawny or cinnamon-brown, often retaining a greenish hue, close, medium broad.

Stipe 3-5 (10) cm long, 4-5 (8) mm thick, "amber-yellow" within, surface "napthalene-yellow," "barium-yellow" to "pale greenish-yellow" above, becoming sordid brown from the base upward, surface covered by a thin coating of yellow fibrils from the veil remnants, apex pruinose and greenish-yellow, becoming hollow, equal.

Spores 7-9 x 4-4.5 µ, smooth, germ pore distinct but apex not truncate; shape in face view oblong to elliptic, in profile slightly bean-shaped to somewhat inequilateral; in KOH dull tawny, in Melzer's reagent paler and more cinnamon; wall about 0.3 µ thick.

Basidia 26-32 x 6-7 µ, 4-spored, narrowly clavate hyaline to yellowish in KOH and yellowish in Melzer's reagent. Pleurocystidia 40-60 (68) x 7-14 (16) µ, fusoid-ventricose with subacute to obtuse apex, smooth or rarely with an ochraceous (in KOH) mucilaginous coating, thin-walled; content hyaline to yellowish, colloidal in the neck. Cheilocystidia (28) 35-55 x 9-13 µ, subclavate, broadly subfusoid, to fusoid-ventricose, thin-walled, smooth or with incrusting ochraceous material, hyaline to yellowish in KOH. Caulocystidia (24) 40-80 (120) x (5) 10-20 µ, mostly clavate, wall thin, ochraceous in KOH, smooth or with bands of incrusting material.

Gill trama of a central area of floccose hyphae the cells inflated to 15 µ or more, yellowish in KOH or in Melzer's and smooth; subhymenium a well developed gelatinous layer of narrow hyaline interwoven hyphae. Pileus cutis a thick gelatinous pellicle of hyaline to yellowish, narrow (2-3 µ) gelatinous hyphae; hypodermial region of incrusted brown hyphae (in KOH). Context of interwoven inflated smooth yellowish-walled hyphae (as revived in KOH). Clamp connections present. All hyphae inamyloid.

Habit, Habitat, and Distribution: On soil, in coniferous woods and on logs, stumps, buried wood, sawdust, duff, and humus; more rarely reported on hardwood (birch, oak, aspen); New York, North Carolina, Tennessee, Michigan, Colorado, Idaho, Montana, Wyoming, Washington, Oregon, California, and Canada (Nova Scotia), June–December; also in Europe.

Observations: This is the most common and variable species in the "spumosa complex" which among others is composed of P. vialis, P. piceina, P. subflavida, P. graveolens, P. fulviconica, P. squalida, P. subamara and P. velata.

In our description we have taken our microscopic data from a collection made in Sweden by Nannfeldt. In it the spore size is 7-9 x 4-5.5 µ. In most collections under the name Flammula spumosa in American herbaria (we have not studied all of them) the spores measure 5.5-8 x 4-4.5 µ. This will be noted by anyone examining our material cited. The lack of macroscopic data on most of the herbarium material we have studied prevents accurate identification of it. The problem here, however, is that of the group as a whole. In order to focus on the features of importance in the recognition of species one first must study the group to ascertain what characters are present, and if possible obtain data on their variability. The only way this can be done scientifically is to set up a classification as we have done here and use it as a testing mechanism with reference to further field studies and studies in culture. The time to pass judgment on the species concepts is after the data have been accumulated and studied, not before, as has been done all too frequently in the past.

We have evidence that the same problem of variants within this complex is present in Europe as well as in North America. A collection by Romell (no. 9782) is an example. The following are our data on it:

Spores 6-7.5 (8) x 4-4.5 µ, smooth, apical pore minute and inconspicuous (under oil); shape in face view elliptic to oblong, in profile very obscurely inequilateral; color in KOH pale ochraceous tawny, in Melzer's scarcely changing; wall about 0.25 µ thick.

Basidia 4-spored, 18-22 x 6-7 µ, clavate hyaline in KOH, yellowish in Melzer's reagent. Pleurocystidia scattered, 36-58 (63) x 8-12 (15) µ, fusoid-ventricose with the "neck" narrowly elliptic in optical section varying to typically fusoid ventricose with a straight neck and obtuse apex; wall thin, smooth, hyaline to yellowish in KOH. Content "empty" or with a plug of yellowish colloidal material in the apex. Cheilocystidia clavate to fusoid-ventricose or ventricose with the "neck" enlarged and apex rounded, smooth, thin-walled, content hyaline to yellowish. Caulocystidia in clusters 40-80 x 7-12 µ, cylindric to clavate, thin-walled, walls smooth, yellowish in KOH; content "empty."

Gill trama with a central area of parallel hyaline thin-walled smooth hyphae 4-8 µ in diam. which are non-gelatinous in KOH; subhymenium of loosely arranged non-gelatinous to subgelatinous (near gill edge) hyphae 2.5-3.5 µ in diam. Pileus cutis a gelatinous pellicle of narrow hyaline to yellowish hyphae with numerous transverse creases as revived (appearing crinkled); hypodermial region rusty-fulvous in KOH, hyphae floccose and fairly heavily incrusted. Context hyphae interwoven, thin-walled, walls smooth (except near hypodermium) and cells inflated. All hyphae inamyloid. Clamp connections present.

Romell's painting with the collection (no. 9782), shows a Pholiota with olive in the coloration and a somewhat dingy stipe much as we know the species in North America but the microscopic features are different and as dried the basidiocarps are a very bright yellow. The subhymenium is not truly gelatinous as revived in KOH. Sections compared give quite a different picture. The pleurocystidia are smaller and have a strong tendency for a secondary enlargement beyond the main ventricose portion in the area normally described as the neck. Also, the spores are "small," as in some American collections.

Kühner and Romagnesi (1953) write: "dans la chair, au moins a la ligne cornée (où l'on voit au microscope de grosses masses jaune-verte intercellulaires, qui manquent chez la précedénte"... (meaning Dryophila lubrica). We have not seen such pigment masses in the course of our study, indicating that very likely the French authors have still another variant. Pilat (1932) gives the spores as 7-8.5 x 4.5-5.5 µ. These are wider in relation to length than in any of the American variants grouped here.

The following is a description of fresh material which appears to belong in this species.

Pileus 3-8 cm broad, convex with an incurved margin, expanding to plane with the margin usually remaining decurved, surface slimy-viscid, at first obscurely spotted with agglutinated veil particles but these soon obliterated, color pale dull tawny, with the margin pale yellow, or at times "tawny" on disc and "warm-buff" on margin, water-soaked margin olivaceous in age, margin fringed at first from fibrils of yellow veil. Context pale yellow with a watery green line above the gills, taste mild, odor faint but reminding one of freshly husked green corn, with FeSO4 olivaceous.

Lamellae pale yellow when young, pale dull cinnamon when mature, more or less subdistant at maturity, broad, adnexed-seceding, becoming ventricose near the stipe.

Stipe 5-11 cm long, 9-17 mm at apex, slightly enlarged downward. yellow over all when young, soon olive-brown to very dingy rusty brown from the base up, thinly fibrillose from the yellow veil but the fibrils discoloring over lower part of stipe, apex silky to fibrillose, no distinct veil-line left at maturity.

Spores in deposit dull rusty brown, 7-9 x 4-5 µ, smooth, with a small but distinct apical germ pore; shape elliptic to ovate in face view, in profile slightly bean-shaped to obscurely inequilateral; color in KOH dull cinnamon, not much different in Melzer's reagent, wall about 0.3 µ thick.

Basidia 15-26 x 5-6 (7) µ, 4-spored, clavate, hyaline in KOH. Pleurocystidia 55-75 (80) x 9-18 µ, fusoid-ventricose, content dull yellow in KOH as revived from a colloidal material in the neck, walls thin and smooth. Cheilocystidia similar to pleurocystidia but with less of a neck, often tapered from ventricose part to the obtuse apex, walls smooth, thin; content ochraceous in KOH. Caulocystidia 50-120 x 10-18 µ, fusoid-ventricose to clavate, often with a secondary cross wall near the base, thin-walled and hyaline in KOH, scattered.

Gill trama with a central area of parallel hyphae the cells of which finally inflate to about 15 µ, walls brownish to hyaline, smooth or nearly so; subhymenium a poorly defined gelatinous to subgelatinous layer. Pileus cutis of narrow gelatinous hyphae 2-3 µ diam., hyaline to ochraceous in KOH, loosely tangled, hypodermium a compactly interwoven layer of hyphae with more or less plate-like rusty brown incrustation, the hyphae of various diameters but thin-walled. Context hyphae thin-walled, hyaline in KOH or nearly so, cells greatly inflated in some hyphae. Clamp connections present.

Habit, Habitat, and Distribution: Caespitose on chip dirt in a mill yard, Cusick, Wash. Oct. 12, 1966. Smith 74157. The mill had been cutting conifer wood entirely.

Observations: This is a common variant, which as far as a comparison of dried material goes is the closest to P. vialis of any Pholiota collected. It was a brighter yellow than material referred to P. spumosa, but does have occasional caulocystidia and a slight odor. The subhymenium is not as gelatinous as it is in specimens assigned to P. spumosa.

Because of the confusion involving the variants of P. spumosa we are not including a list of material studied. Herbaria are full of specimens in this group but the data to accurately classify them are lacking for the most part. As mentioned many times previously for other groups, carefully correlated field and culture studies seem to be the approach most likely to furnish a better understanding of the complex.