Stemonitidae

Stemonitidae is a family of slime molds belonging to the order Stemonitales. These organisms are characterized by their stalked sporangia, which typically form a dark, often black, spore mass. The stalk is usually distinct and well-developed, arising from a persistent hypothallus, which is a dark, membranous layer that can be visible at the base of the sporangia.

The plasmodium, the vegetative stage of a slime mold, is typically a network of protoplasmic strands that moves and feeds on bacteria and fungal spores. When conditions are unfavorable, the plasmodium differentiates into fruiting bodies, or sporangia. In Stemonitidae, these sporangia are often slender and cylindrical or clavate (club-shaped). The peridium, or outer wall of the sporangium, is usually thin and evanescent, meaning it breaks down early, revealing the spores.

The capillitium, a network of sterile threads within the sporangium, is a key feature for identification within this family. In Stemonitidae, the capillitium is often well-developed and elaborate, branching extensively and connecting to the sporangial wall. The spores are typically dark brown or black and may be smooth or minutely ornamented.

Common genera within Stemonitidae include Stemonitis, Comatricha, and Clastoderma. These slime molds are found in damp, shaded habitats worldwide, often on decaying wood, leaf litter, or other organic debris. Their ecological role includes the decomposition of organic matter and serving as a food source for various invertebrates.