I live in the Florida panhandle, and I have two 20" flowerpots with two tomato plants in the first pot and a bell pepper and three zucchini plants in the other. They are on a south-facing balcony but only get partial sun because of the porch pickets.

Yesterday I noticed a strange fungus (slime mold) covering the bottom third of a small, fuzzy Easter bunny ornament glued to a wooden skewer, pushed into the dirt near the edge of one of the containers. After removing and discarding the decoration, I scraped off the remainder growing on the surrounding soil and the side of the container. I scooped out the contaminated dirt and spores, or so I thought.

This morning, I noticed the fungi (slime mold) had reappeared overnight, spreading rapidly and covering much of the soil surface and some of the lower zucchini leaves. The appearance could be described as clumps of dark brown, almost black, cylindrical rods jutting up from a network of translucent webbing (mycelia), which coat the soil's surface. These rods, while tightly grouped, are each distinct from one another, appearing almost as if they were the fossilized tentacles of some ancient sea anemone.

I spent over an hour online trying to identify what is plaguing my precious veggies. I even tried using Bixby Vision and Google Lens to match my images with similar photos online. Still, I saw nothing conclusive in the search results.

I suspect it may be a mulch fungus since the containers are filled with Sta-Green Potting Soil Mix, a low-budget potting soil comprised mainly of finely shredded bits of bark and mulch. Does anyone know what type of fungus or mold this is and whether I need to be worried about it killing off my plants or making them toxic to eat?

a slime mold with dark brown, rodlike vertical clusters and a slimy webbed base covers the surface of the soil

a closeup view of the mysterious slime mold with its dark brown, rodlike vertical clusters

a perspective-based view which shows how quickly the slime mold was able to muliply, almost spanning the width of a 20" pot in a single night.

a closeup shows the mold smothering a zucchini leaf, demonstrating how pervasive these spores can become once activated

  • 2
    Not a fungus but a slime mould. I don’t recognise this one. Not a problem! Those good pictures. Commented Apr 10, 2023 at 2:42
  • Probably Tubifera genus of slime mould. Commented Apr 10, 2023 at 8:03
  • @PolypipeWrangler, could it be the Stemonitis genus of slime mold? Stemonitis fusca, in particular, seems to be a very close match, visually speaking.
    – killshot13
    Commented Apr 22, 2023 at 5:31

1 Answer 1


This is Chocolate Tube Slime (Stemonitis splendens) of the genus Stemonitis, a type of slime mold.

It is typically found on fallen trees and decaying wood.

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Source: https://www.inaturalist.org/photos/23595573, Photo 23595573, (c) Reflectitur Photons, some rights reserved (CC BY-NC), uploaded by Reflectitur Photons

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