Phlyctis agelaea (Ach.) Flot.
Lecanora agelaea (Ach.) Flotow.
Thallus crustose, thin, smooth to slightly cracked, up to 5-10 cm in diameter, whitish, greyish-white, pale greenish-white in dry weather (see Phlyctis agelae old & dry), greenish-white to greenish in wet weather, often bounded by a whitish hypothallus. Apothecia buried by 2-4 in the center of flattened warts 0.2-1 mm in diameter, disc reddish-brown (if visible and fresh), at first the warts are covered with a dense whitish almost membranous bloom that opens by getting lost (like a Gyalecta!) and showing the apothecia. Asci with 2 spores (very rarely 4), largely claved. Spores typically in "pea pod" with an apicle at each end, muriform, hyaline then greyish so well ripe, 50-80 x 12-25 µm according to the literature, 50-70 x 20-30 µm according to our measurements. Pycnidia submerged in the thallus, black. Photobiont: chlorococcoid. C-, KC-, K + yellow then red (sometimes weak and only on fertile warts), P + golden yellow (especially on fertile warts). Species occurring on trees with acid bark (Quercus, Ilex, Salix, etc.) in moist woods.