Rudi and I recently went for a wander around Parc Slip hoping to find signs of a little known fungi, Taphrina which is a genus of parasitic Ascomycota that cause intriguing galls in their host plants. Witches Broom (Taphrina betulina) is the largest and most familiar species inducing dense twig-like formations on Birch's which are the host tree, these sometimes reach the size and shape of a squirrels drey (they are most conspicuous on leafless trees in winter). Pocket Plum (Taphrina pruni) affects Blackthorn and causes the fruits (Sloes) to become green and runner bean-like in appearance. But we were looking for Taphrina alni commonly known as Alder Tongue which grows on the fresh cones of Common Alder.
Now, looking for signs of a specific fungi almost always lead to disappointment, but not today. As we set off from the Parc Slip car park we were little more than 10 paces into our walk when we spotted the flaming red tongues of the fungi. As we walked around the reserve we saw the galls on a number of Alder trees with some trees having more than 30 infected cones.
The cones may carry several tongue galls, each of which usually comes from the same position. Those curling down usually come from the bracteoles tissues and those projecting upwards usually come from ovarian tissues. The gall was rare in Great Britain but seems to have become quite common and has been frequently spotted since the 1990's.
The galls mature on the cones with the spores travelling on the wind to infect neighbouring trees. The gall, known as a 'languet' (something that resembles a tongue) emerges from between the outer scales like a flat shaped elongated flag with a hard and slightly shiny surface. The surface is smooth, lacking any hairs. Early in the season the gall is fresh and green, but the colours soon start to vary from pale green to yellow, pink, red, purple and orange. Later the galls turn brown or black and remain on the tree until the next season.
Mike and Rudi Bright of the Bridgend Group