Stemonitis flavogenita

🏷️ Description

Nature is full of strange and beautiful things — and few are as overlooked and quietly fascinating as slime molds. Among them, one species stands out for its delicate structure and color-changing ways: Stemonitis flavogenita E. Jahn (1904). Let’s get to know this shy but stunning forest dweller. 🍄✨

🦠 What Is Stemonitis flavogenita?

Stemonitis flavogenita is a species of slime mold — not a fungus, not an animal, but a curious organism that moves and feeds like an amoeba before forming spore-bearing structures. It belongs to a group called myxomycetes, known for their dramatic transformations and shimmering, colorful plasmodium stage. 🌈

🔍 How to Recognize It

The sporangia (spore cases) of S. flavogenita are:

• 📏 4–10 mm tall

• 🌰 Cylindrical and blunt-tipped, forming tight clusters

• 🍂 Wood-brown to reddish-brown, becoming lighter as they release spores

• 🖤 Set on short, black stipes (stalks) making up about 1/3 of the total height

At the core of each sporangium is a columella — a slender black rod that extends nearly to the top and finishes with a quirky zigzag-like curve ending in a delicate membrane-like plate. It’s this feature, along with its taller sporangia, that helps distinguish S. flavogenita from its more common cousin, S. axifera. 🧐

🔬 Inside the Slime Mold

The capillitium, or internal network, is a fragile, fine mesh with numerous membrane-like expansions. It forms a delicate net over the surface of the sporangium and can be identified by:

• 🕸️ Thin, varied-sized meshes

• ⚪ A tendency to break down quickly at the top

• ✨ Occasionally visible spine-like ends in some specimens

Spores are:

• 🍫 Reddish-brown in mass

• 🍇 Purplish-brown in transmitted light

• 📏 7–9 µm in diameter

• 🔍 Covered with tiny warts

And when active as a plasmodium — the moving, feeding stage — it glows a gentle lemon-yellow 🍋, sometimes pale or white.

🌳 Where Does It Grow?

Stemonitis flavogenita thrives on:

• 🌿 Decaying wood of both conifers and broadleaf trees

• 🍂 Plant debris

• Occasionally found on the bark of living trees

🗺️ Where Can You Find It?

Though considered rare in many areas, this slime mold has a surprisingly wide distribution:

🇬🇧 Common on the British Isles

🇰🇿 Kazakhstan, Siberia, 🇺🇦 Ukraine

🇯🇵 Japan

🌎 North and South America

🌍 Parts of Europe, Asia, and Africa

It’s often overshadowed by the more abundant Stemonitis axifera, but careful observers can find it — especially in damp, decaying forest environments. 🌲

Photo sources:

Photo 1 - Author: Karol Filo III (CC BY 4.0)