Phallus hadriani

The species was first described scientifically by the French botanist Étienne Pierre Ventenat in 1798,[3] and sanctioned by Christiaan Hendrik Persoon under that name in his 1801 Synopsis Methodica Fungorum.[4] Christian Gottfried Daniel Nees von Esenbeck called the species Hymenophallus hadriani in 1817;[5] this name is a synonym.[1] According to the taxonomical database Index Fungorum, additional synonyms include: Phallus iosmus, named by Berkeley in 1836; Phallus imperialis, Schulzer, 1873; Ithyphallus impudicus var. imperialis and Ithyphallus impudicus var. iosmos, De Toni, date unknown.[2]

The specific epithet hadriani is named after the Dutch botanist Hadrianus Junius (1512–1575),[6] who wrote a pamphlet on stinkhorn mushrooms in 1564 (Phalli, ex fungorum genere, in Hollandiae).[7]

The pink volva is what remains of the tough outer covering of the immature egg.

The immature fruiting bodies of P. hadriani in the egg stage have dimensions of 4 to 6 cm (1.6 to 2.4 in) by 3 to 4 cm (1.2 to 1.6 in), and are colored rosy-pink to violet.[8] They typically have rhizomorphs (aggregations of mycelium that resemble plant roots) at the base.[9] The eggs are enclosed in a tough covering and a gelatinous layer that breaks down as the stinkhorn emerges. Mature fruiting bodies, which may be 10 to 20 cm (3.9 to 7.9 in) tall by 3 to 4 cm (1.2 to 1.6 in) thick, have a white- or cream-colored hollow stipe that is spongy and honeycombed. The head is reticulate, ridged and pitted, and covered with olive green glebal mass. The volva is cuplike, and typically retains its pink color although it may turn brownish with age. Fruit bodies are short-lived, typically lasting only one or two days.[10]

Although the odor of P. hadriani has been described by some authors as faint and pleasant[11] or like violets,[12] others describe the smell as fetid or putrid.[13] The gleba is known to attract insects, including flies, bees, and beetles, some of which consume the spore-containing slime. It is thought that long-distance spore dispersal is facilitated by these insects, who may deposit in their feces intact spores that survive the passage through the digestive tract.[12]

The spores are cylindrical, smooth, and hyaline (translucent), with dimensions of 3–4 by 1–2 µm.[14] The basidia (spore-bearing cells) are cylindrical, with dimensions of 20–25 by 3–4 µm. They have eight sterigmata (slender extensions that attach to the spores), as well as a clamp at their base.[11]

Edibility

A cross-section of the immature, edible egg-form

Like many other stinkhorns, this species is thought to be edible when in its egg form.[10] Central Europeans and the Chinese consider the eggs a delicacy.[15] Regarding the edibility of mature specimens, one author commented on the genus in general, "No one with his sense of smell developed would think of eating the members of this group."[16]

Phallus hadriani is known to be in Australia (where it is thought to be an introduced species imported on woodchip mulch used in gardening and landscaping),[13] North America,[10] Europe (including Denmark,[18] Ireland,[19] Latvia,[20] The Netherlands,[21] Norway,[22] Poland,[23] Slovakia,[24] Sweden,[25] Ukraine,[26] and Wales[27]) Turkey (Iğdır Province),[11] Japan,[28] and China (Jilin Province).[29]

Phallus hadriani is a saprobic species, and thus obtains nutrients by decomposing organic matter. In North America, it is commonly associated with tree stumps, or roots of stumps that are decomposing in the ground.[14] In Great Britain, its distribution is more or less restricted to coastal dunes,[30] while in Poland, it has been noted to avoid humid and humic forest soils, and live in symbiosis with xerophilous grasses and the black locust tree, Robinia pseudoacacia.[31] The mushroom is one of three species protected by the Red Data Book of Latvia.[20]