Hysteriaceae

The Hysteriaceae are a taxonomic family of fungi and the only extant family of the order Hysteriales. Members of the Hysteriaceae are defined by the possession of a sexual structure called the hysterothecium, an elongated structure that opens by a longitudinal slit and releases sexually produced spores. The family is widely distributed, with many species found in temperate regions, and most are saprobic on wood and bark, although a few are parasitic on plants.

==Description== The defining feature of this group—the hysterothecium—is a dense, persistent darkly colored structure, with a boat-like shape and a pronounced lengthwise slit. Hysterothecia are capable of opening partially to reveal a lenticular (lens-shaped), disk-like hymenium or closing tightly in response to relative humidity. They can be embedded in the substratum, bursting through the surface of the substratum (erumpent), or rest entirely on the surface. They can be solitary or in groups, ellipsoid to greatly elongated, and are sometimes branched, triradiate or borne on a crust- or net-like growth of mycelium (a subiculum). In vertical section, hysterothecia are globose to inversely ovoid (obovoid), with a thick three-layered peridium, composed of small pseudoparenchymatous cells, the outer layer heavily encrusted with pigment and often longitudinally striated in age, the middle layer lighter in pigmentation and the inner layer distinctly thin-walled, pallid and compressed.