Dog stinkhornMutinus caninus

The dog stinkhorn (Mutinus caninus) is a slender relative of the common stinkhorn. It grows out of a small white 'egg', and at the top of its pale, spongy stem sits an orange tip covered in dark olive slime that carries the spores. The slime attracts flies, which carry the spores away on their feet and in their guts, a little like insects pollinating flowers. It was first named by Jacob Christian Schaeffer in 1774, and William Hudson recorded it from Britain in 1778.

How do you identify a dog stinkhorn? It starts as a white or yellowish 'egg' 2 to 3 cm across, half buried in leaf litter, with white cords at the base. Inside, under the skin, there's a layer of clear jelly around the folded stem and its dark olive core. Within a few hours a slender, hollow stem pushes out, 6 to 15 cm tall and about 1 cm thick, spongy like expanded polystyrene, white, pale yellow or pale orange and often curved. There's no separate cap: the top of the stem is simply orange-red and pointed, and only its upper part is covered in sticky olive slime. Once flies have eaten the slime, the tip shows bright orange, and the whole thing collapses within three or four days. The remains of the egg stay as a sac at the base. The smell is unpleasant but much weaker than the common stinkhorn's.

Where does it grow? In broadleaved and conifer woodland, on rich humus, in leaf litter and near rotting stumps and logs, usually in small groups. It also turns up on old woodchip mulch in parks and gardens. It's much less common than the common stinkhorn, and it fruits from late summer to late autumn, most of all in early to mid-autumn. In Ukraine it's rare and protected in the national Red Data Book.

Is the dog stinkhorn edible? No, it's inedible; we found no reports of people being poisoned. There are reports of dogs falling ill after eating mature ones, so keep dogs away from it, and if your dog eats one, call your vet.

Why is the egg risky? A white egg in the leaf litter could be a young death cap or destroying angel, and you can't tell them apart by size or smell. Cut the egg in half from top to bottom. A stinkhorn egg shows a layer of jelly and an olive core, and no gills. A young amanita has no jelly; instead, the cut shows the outline of a small mushroom, with a cap, gills and a stem. Cutting helps you identify the find, it doesn't make it safe to eat: if the section isn't clear, treat it as a death cap. Death cap poisoning gives the first symptoms only around 6 to 24 hours after eating, often followed by a deceptive improvement while the liver is being damaged. If anyone may have eaten an 'egg' or a mushroom that could be an amanita, get help straight away, even if they feel fine: call emergency services on 112 (999 in the UK) or your local poison centre and keep any leftovers.

What else can you mistake it for? The common stinkhorn is much bigger and stouter, 15 to 25 cm tall, with a separate bell-shaped cap that's white under the slime, and it smells so strongly you can find it by nose. The dune stinkhorn is also large and capped, and its egg and sac are pink to violet. Young puffballs are uniformly white inside; the common earthball is firm and soon dark purple-black with white veins. Outside our catalogue, the raspberry stinkhorn (Mutinus ravenelii) has a pink to red stem and is shorter and stockier.