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Species Information
Summary: {See also Morels Table.} Features include a hollow cap with pits and ribs, lacking a free skirt-like margin, the pits generally more round than elongate when mature, and colored pale grayish tan, becoming tan to ochraceous, the ribs at first colored as the pits, becoming paler, the stem hollow, more or less round in cross-section but often appearing pleated at base, and growth under hardwoods, especially Fraxinus (ash) and black cottonwood, but also apple and elm. |Morchella americana is briefly described as a new species by Clowez(1) growing under Fraxinus americana (white ash) and in relation to Morchella esculenta of Europe as being often identical in color but with pits that are more numerous, slightly longer, smaller and less regular than in M. esculenta. |Morchella americana was more extensively described as Morchella esculentoides M. Kuo, Dewsbury, Moncalvo & S.L. Stephenson, but the former name has priority. Clowez(1) refers to the Kuo concept in describing Morchella americana. The Kuo et al. description for M. esculentoides is paraphrased here too for comparison (Kuo(6)), as well as an older one for Morchella ''esculenta'' in North America derived from Weber(3). |These taxa have been known in North America under the European name Morchella esculenta (L.: Fr.) Pers., but molecular research indicates that different taxa are involved. |Morchella americana is said to be common in many areas in the east of the US and Canada. Morchella esculentoides is said to be widely distributed and common east of the Rocky Mountains (including the Great Lakes region): in western North America it is found in river bottoms or in urban areas, (Kuo(6)). |M. Beug (pers. comm.) says in the Pacific Northwest Morchella americana is typically found under black cottonwoods in river bottoms. |Clowez(1) also described Morchella californica Clowez & D. Viess associated with Fraxinus dipetala in California, but this has been synonymized by Richard(1). |A morel that fits the classical concept of M. esculenta occurs in eastern Oregon (different from PS E mentioned under Morchella species), (Pilz(1)). |The name ''Morchella crassipes'' has been used to refer to a yellow morel found late in the season with a swollen stem, but these have often proven to be a growth form of the yellow morel, (Kuo(1)).
Collections of M. americana (as M. esculentoides) were examined from OR, ON, AR, CA, CO, IA, IL, KS, MA, MN, MO, NE, NY, OH, OK, PA, SC, SD, TX, VT, VA, WI, WV, (Kuo(6)). It also occurs in central Europe (Richard(1)). There are six collections as Morchella esculenta from BC at Pacific Forestry Centre in Victoria, and 4 collections from BC at the University of British Columbia (as well as one as M. deliciosa under Populus in sand), some of which are likely to represent this species.
Cap: 1.5-4.2(12.6)cm across at widest part, 2.3-11(22)cm high, (whole fruitbody 3.6-22(41.5)cm high), usually ovoid with bluntly conic or convex apex but occasionally subcylindric with convex apex or nearly spherical to pear-shaped, "pitted and ridged, with approximately 12-30 vertical ridges and numerous horizontal and oblique ridges, along with scattered, sunken, transecting ridges", "adnate at the point of attachment", pits "usually more or less vertically elongated but not strictly so and not infrequently subglobose to irregular in outline"; color of ridges "white to pale yellowish when young, becoming pale brownish yellow or remaining whitish" when mature, pits "grayish brown to dark brown or nearly black when young, becoming pale brownish yellow"; surface of ridges bald or nearly so, "bluntly rounded or nearly flattened when young" usually becoming sharpened or eroded when old, surface of pits bald or finely tomentose, (Kuo(6)), 2-7(8)cm across at widest part, 2-10(17)cm high, hollow, lacking prominent free margin (tissue intergrown with stem), oval to nearly cylindric or slightly narrowing towards top but seldom strongly conic, outer surface composed of pits and ridges, pits "generally more round than elongate in outline at maturity", then often 0.4-4cm long and 0.3-1.5cm wide, lined by spore-bearing tissue, main ridges to 1.5cm high and 0.3cm wide; pits "when very young pale dingy grayish tan, soon developing strong gray tones as the pits open up, these fading and usually replaced by tan, dull ochraceous, or golden tan colors by the time spores are mature", ridges at first colored as pits and close together, as cap expands becoming paler than the pits, "usually white to creamy white then stained rusty yellow or dingy brown", but where the surface of the ribs flakes or tears away and exposes the underlying tissue, again colored as pits; surface of ribs more waxy than velvety, (Weber)
Flesh: 0.1-0.3 thick in the hollow cap, in the stem "often becoming thickened and chambered near the base with maturity"; whitish, (Kuo)
Underside: sterile inner surface "whitish and pubescent", (Kuo), interior of hollow cap "uneven and decorated with cottony or scaly patches of white to whitish tissue" (Weber)
Stem: 2-12(24)cm x 1.6-9.2(14)cm, usually basally clavate to subclavate [somewhat club-shaped], "whitish to pale yellowish or brownish"; bald "or finely mealy with scattered whitish to yellowish granules", (Kuo(6)), 2.5-8(10)cm x 2-4.5cm, hollow, equal to widening slightly downwards, basically round in cross-section, base "often enlarged and appearing pleated or gathered"; "off-white to ivory or pale cream color"; finely pruinose at first, surface "stretched" apart when old, (Weber)
Microscopic: spores 20-23 x 10-13 microns, asci 300 x 15 microns; paraphyses sparse, (some in the form of a bouquet), composed of 3 or even 4 cylindrical cells, the terminal one always larger 70-80 x 10 microns; elements on edges of ridges 40-90 x 15-25 microns, clavate, (Clowez), spores (17)18-22(24) x 11-13(15) microns, elliptic, smooth, homogeneous contents; asci 8-spored, 225-325 x 15-25 microns, cylindric, colorless; paraphyses 75-180 x 5-15 microns, cylindric, tips "generally merely rounded but occasionally subclavate to clavate or subfusiform", septate, colorless to ochraceous or faintly brownish in 2% KOH; elements on sterile ridges 75-160 x 10-27.5(37.5) microns, colorless to ochraceous in 2% KOH, septate, "terminal cell subclavate to clavate, or subfusiform to widely cylindrical with a rounded or subcapitate apex", (Kuo(6)), spores 21-25(28) x 12-16 microns; asci 180-250 x (15)18-20 microns; paraphyses "typically considerably shorter than mature asci and inconspicuous to nearly impossible to find in a mature specimen", clavate to rounded at top, 6-12 microns wide at widest point, colorless when mature specimens revived in KOH, (Weber)
Habitat / Range
in western North America "under hardwoods in river bottoms or in urban settings in association with apple trees or ornamental ash plantings", in the east of North America common, often found under living and dead hardwoods, especially living Fraxinus americana (White Ash) and dead or dying Ulmus americana (American Elm), and occasionally in association with conifers; fruiting in spring, (Kuo(6)), single to gregarious or clustered, "in a wide variety of habitats, including hardwood forests", "under mature to old fruit trees (especially apples), around dead American elms, under white pines, on sand dunes and many other places", (Weber), M. claviformis under Acer (maple), and M. populina under Populus (cottonwood etc.) are considered synonyms (Richard(1)), in North America it is found "in a variety of habitats, often associated with white ash but also found near dead elms, in old apple orchards, riparian areas, burned areas, or mixed hardwood forests, sometimes under conifers, often on steep slopes or along old railroad beds", in spring and early summer, (Beug(3))
Similar Species
Morchella tridentina, the mountain blond morel (PS E), also occurs away from fires and has the ribs separating the pits lighter in color (ivory to nearly white) than the lining of the pits when old. By maturity the ribs are off-white sometimes with amber stains and bruises. Pits are gray when very young, becoming tan, golden, or straw yellow when mature. It differs from most descriptions of M. esculenta from Europe or elsewhere in North America in that 1) it has a relatively narrow head, rather than oval or rounded, especially in young specimens, 2) "the primary ribs are strongly vertical and relatively straight producing elongated pits rather than the rounded to somewhat irregular pits generally attributed to M. esculenta [Latin name in italics]", and 3) it "seems to be characteristic of conifer forests including either lodgepole or ponderosa pine, whereas the complex centered on M. esculenta [Latin name in italics] is commonly associated with hardwoods sometimes mixed with conifers." (Pilz). Kuo (2006) calls M. tridentina (as M. frustrata) the western blond morel "to reflect the fact that the Western Blond is found not only under conifers at high elevations but also under hardwoods at lower elevations". The colors, he says, suggest a yellow morel, since the ridges do not darken with age and the overall color of the cap is fairly pale throughout development--though the mature cap colors are just a little bit browner than the colors of the typical yellow morel. The stature of the Western Blond, however, ''suggests a black morel; the pits and ridges are more vertically arranged than those of the esculenta-like yellow morels, and the cap attaches to the stem with a shallow "rim"--a feature not usually found with yellow morels.'' (Kuo(2)). Morchella prava (known from BC, OR, ON, SK, MT, and SD and reported from WA) is distinguished by dark pits and a very contorted head, (M. Beug, pers. comm.). M. prava "usually can be identified on the basis of its esculenta-like stature and its contorted, asymmetrical and irregular pits and ridges. The pits are highly irregular in outline and size, and the thick, bluntly rounded ridges are less likely to become eroded and sharpened with maturity than the ridges in M. esculentoides"; the cap "often appears like a contorted or somewhat deformed version" of the M. esculentoides cap. Significant microscopic differences from M. esculentoides were not observed although the elements on sterile ridges in specimens studied generally were sparsely scattered or nearly absent, whereas they were easily located in M. esculentoides. (Kuo(6) with the Latin italicized). M. prava is one of three species that has been known in the past by the name Morchella deliciosa, commonly found in field guides. Morchella deliciosa refers to a European morel described by Fries. It was described for North America by Weber in 1995 and documented for eastern North America. Kuo(6) do not recognize M. deliciosa of Europe for North America and describe three eastern North American species that have been considered as M. deliciosa in the past, one of them being M. prava. According to Kuo (1), the mushrooms are small in comparison to the classic North American yellow morels [i.e. to what are later called M. esculentoides], and the pits and ridges are sparser proportionally and more vertically arranged. Additionally the caps are frequently but not always more pointed. (Kuo(1)). What has passed for Morchella deliciosa in California is thought to be Morchella rufobrunnea (the blushing morel), described from Mexico in 1998. The trademark physical features of Morchella rufobrunnea, according to Kuo(2) are the frequently pointed cap (especially when young), the striking contrast of the light-colored, vertically arranged ridges and darker pits in young mushrooms, and the fact that it is rufescent, meaning that it blushes pinkish to salmon oRANGE when bruised, especially when young.
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