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Jelly fungi like witch's butter that swell with rain and shrivel dry

October to March

Witch's butter and its relatives are jelly fungi: yellow-orange or dark brown rubbery blobs that swell up on dead branches after rain. A few dry days later the same blob shrivels to a hard crust glued to the bark, and the next wet spell swells it back in the same spot.

Why this time of year

From October into March, rain and snowmelt keep soaking and drying the same dead sticks. What you are watching is not new growth but an autumn-built body rehydrating over and over, which is exactly why a branch you check one week is worth checking again the next.

How to notice it

  1. The day after rain, look along dead branches still attached to a tree, and at fallen oak sticks. You want a blob about the size of a walnut that looks wet even where the bark is dry.
  2. Touch it with one fingertip. It should feel cool and rubbery and spring back rather than crumble. Leave it on the branch.
  3. Remember which branch it is. Take a photo, or count the branch out from the trunk. This is the whole point of the card.
  4. Go back after three or four dry days. It will be a thin dark crust flattened onto the bark, easy to walk straight past. Come back again after the next rain and watch it swell in the same place.

Try this with kids: Press it gently on a wet week, then find the same spot on a dry week. How many times can you catch the same blob changing before spring?

a jelly fungus is mostly water held in a gel, so it can dry to a crust and revive instead of having to grow a new body

Safety

  • Do not eat, taste or collect anything on this card. It is about touching and watching, and it deliberately does not teach you to tell one jelly from another.
  • Do not pull, break or reach up for dead branches. Dead wood overhead is the hazard here, not the fungus.
  • Poison ivy climbs dead trunks and its bare winter vines still cause a rash. Look at what your hand is about to rest on.
  • Leave the fungus attached. Prying it off ends the thing you came back for.

Sources

  • northernwoodlands.orgNorthern Woodlands, Joe Rankin. The core mechanism, verbatim: rather than having to build new spore-producing components from scratch like most cap mushrooms, jelly fungi just have to rehydrate their bodies. Also that mid-winter blobs formed in the cool damp days of autumn and are not likely to be growing while the organism remains very much alive, and that witch's butter is a parasite on the mycelium of a wood-decay fungus.
  • northernwoodlands.orgNorthern Woodlands, Frank Kaczmarek: tough shelf and bracket fungi including turkey tail persist year-round, while soft-bodied species including jelly ear fruit from late autumn into early winter, and the jellies are not actively growing in winter but are remarkably durable and expand back to normal size during rain or snowmelt. This is also the duplicate test against the existing turkey tail entry, drawn by the same author in the same sentence pair.
  • massaudubon.orgMass Audubon, Habitat Wildlife Sanctuary in Belmont: many species of jelly fungi shrivel up when dry to conserve energy, then rehydrate in water. Independent confirmation of the whole behaviour from a Massachusetts organisation, tied to an October walk in eastern Massachusetts.
  • thoreaufarm.orgWinter fungal forays at Estabrook Woods, Concord, eastern Massachusetts, led by a named mycologist. The February 3 species list of 41 fungi includes Exidia recisa, brown witches butter, marked 'everywhere', alongside Tremella. This is the local deep-winter occurrence evidence and it sits about ten miles from Sudbury.
  • mushroomexpert.comMichael Kuo: grows on recently fallen hardwood sticks and branches, especially oak, and blackens along the edges when dried out. Note this reference gives the species' season as spring through fall, so the deep-winter months here rest on the Estabrook February record plus the persistence-not-growth mechanism rather than on this page.
  • botit.botany.wisc.eduThomas J. Volk, University of Wisconsin-La Crosse: all members of the genus Tremella are reported to be parasitic on wood decay fungi. Cited only for that claim.

Checked against these sources on September 6, 2026.

In the guide for October, November, December, January, February, March

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