Helvella fibrosa

The fruiting body of Helvella fbrosa is delicate and small, with the cap (apothecium) measuring 5–20 mm across. When young, the apothecium resembles a cup that has been squashed from above; as it matures, it flattens into a plate-like form and its margin often splits into radial fragments. The spore-bearing surface, or hymenium, is smooth and varies in colour from grey through dark grey to brownish-grey, while the exterior (sterile surface) is covered in fine hairs, giving it a downy (pubescent) texture and a grey to grey-brown hue. The stalk, or stipe, typically stands 10–35 mm tall—usually exceeding the width of the apothecium—and is 2–6 mm thick. It is more or less cylindrical, sometimes curving slightly at the base, and bears a similar downy covering; its colour is generally grey, though creamy white forms are occasionally encountered. Under the microscope, the spore-bearing cells known as asci are cylindrical, measure 245–310 μm by 12–14 micrometres (μm), and each contains eight spores. These asci are single-walled (uniseriate), arise from a hooked basal cell (a crozier), and do not react to iodine stains (inamyloid). The ascospores are smooth, transparent, ellipsoid structures about 16–20 μm long and 10–12.7 μm wide, each containing a prominent central oil droplet and staining readily with certain dyes (cyanophilic). …

Helvella fibrosa has a worldwide distribution. It is relatively common in deciduous and mixed forests of Europe, where it grows in humid habitats. Some countries in which the presence of this species has been confirmed with DNA analysis include Denmark, Finland, Iceland, Norway, and Sweden. H. macropus is a relative with which it has been confused many times.

== References ==