Wrinkled Thimble Morel Verpa bohemica — the early morel of cottonwood river bottoms
Verpa bohemica, also called the early morel or wrinkled thimble-cap, is one of the first mushrooms of spring in the Pacific Northwest. It grows under cottonwoods along rivers and streams, mostly in March and April, and usually shows up 1–3 weeks ahead of true morels (Arora).
It is often called a false morel, but unlike Gyromitra it belongs to the true morels’ own family, Morchellaceae. Its edibility is disputed: Mushrooms of Cascadia (Siegel & Schwarz) lists it as edible, while poisonings have been reported (see Edibility below). Two field checks separate it from true morels.
Find Cottonwood River Bottoms on Forayz
Use satellite basemaps and public land layers to scout cottonwood riparian areas — prime Verpa habitat. Snow cover layers help you time the spring melt.
Identification
| Feature | Description |
|---|---|
| Cap | 1–7 cm wide and 2–8 cm high; shaped like a thimble or bell, sometimes cylindrical. Deeply wrinkled, with ridges running lengthwise. Ocher-brown to brown. Attached only at the very top of the stem — the margin hangs free like a thimble on a rod. |
| Cap Underside | Finely fuzzy (tomentose), tan to light brown. Visible when you lift the cap margin away from the stem. |
| Stem | 5–15 cm long (occasionally to 22 cm) and 1–3 cm wide, even or thickening toward the base. Whitish to buff or pale ocher, dusted with fine pale granules or chevron-like bands. Interior stuffed with cottony pith; old specimens can become hollow. |
| Flesh | Thin and fragile. |
| Odor/Taste | Indistinct. |
| Spores | Very large (55–87 × 17–22 μm), cylindrical. Two-spored asci — a useful microscopic distinction from Verpa conica (eight-spored asci). |
Two field tests separate Verpa from true morels
Cap attachment: On Verpa, the cap is attached only at the very top of the stem — you can easily push the cap margin away from the stem and see a gap. True morels (Morchella) have caps joined to the stem for most of their length, or for about the upper half in M. populiphila.
Stem interior: Slice the stem lengthwise. Verpa stems are filled with cottony pith. True morels are hollow with a single continuous chamber through both cap and stem. Old Verpa can become hollow (Breitenbach), so check the cap attachment as well.
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Habitat & Where to Look
Verpa bohemica grows mainly with cottonwoods. Look under black cottonwoods (Populus trichocarpa) along rivers, streams and floodplains; Ammirati also lists willows and aspens. It fruits in the leaf litter and duff, singly or in scattered troops.
The challenge: The ocher-brown caps match fallen cottonwood leaves, and they are often partly or wholly hidden under the litter (Ammirati), so it can pay to brush dead leaves aside.
Distribution: Common in cottonwood habitat throughout the region, on both sides of the Cascades.
If you hunt morels, note where you find Verpa. Mushrooms of Cascadia places two morels with cottonwoods: Morchella brunnea, which is common and also grows with snowbrush in east-side forests, and the less common American yellow morel (M. americana), found in riparian areas with cottonwood or ash.
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Season & Timing
Verpa bohemica fruits in early spring; in the mountains it follows snowmelt. iNaturalist observations from Oregon and Washington peak in April, with most of the rest in March and May:
Based on community observations from Oregon and Washington
Because it typically fruits 1–3 weeks before true morels (Arora), finding it suggests the local morel season is close.
Edibility
Sources disagree. Mushrooms of Cascadia lists Verpa bohemica as edible, and many people eat it. Arora notes that it can cause severe stomach cramps and loss of coordination, especially when eaten in large amounts on several days in a row. A 2020 toxicology review (Lagrange & Vernoux, Toxins) calls its status unclear: it notes poisonings in the NAMA case registry and reported alcohol-intolerance reactions, and recommends against eating it. Many North American field guides list it as suspect.
If you choose to eat it
Cook it thoroughly; traditionally it was parboiled and the water discarded (Benjamin). Thorough cooking often lowers the chance of a reaction but does not rule one out. Eat a small amount the first time, don’t eat it in quantity or on successive days, and avoid alcohol with it. Some people react more than others. For a deep dive into the toxicology of morels and morel relatives, see our Morel Toxicity Guide.
Similar Species
- Morchella populiphila (a half-free morel): Same cottonwood habitat, but far less often reported than V. bohemica. Cap is pitted and ridged, thimble-shaped to conical, and attached at about its midpoint rather than only at the top. Cap and stem are hollow, one continuous chamber.
- Verpa conica (Smooth Thimble-cap): Similar thimble shape and free cap attachment, but cap is smooth to slightly wrinkled (not deeply furrowed like V. bohemica). Smaller overall. Grows under a wider range of trees, conifers included, and is uncommon. Has 8-spored asci (vs. 2-spored in V. bohemica). Mushrooms of Cascadia treats it as a group of at least three species in the region.
- Morchella species (True Morels): Caps are pitted in a honeycomb pattern and joined to the stem for most of their length, with a completely hollow interior. V. bohemica‘s ridges sometimes branch into shallow pits (Arora), so check the attachment rather than the surface alone.
- Gyromitra species (False Morels): Brain-like, lobed or saddle-shaped caps rather than a thimble. Some contain gyromitrin and are toxic; see the Gyromitra guide.
Sources: Mushrooms of Cascadia (Siegel & Schwarz, 2024); MycoMatch (© Ian Gibson), a compilation of published descriptions through which most other field-guide authors named here are quoted; iNaturalist observations.