Candelariella flavosorediata presents itself as a scatter of minute, bright-yellow "islands" on the
substrate. Each island, or , is only about 0.1–0.3 mm across and has an irregular outline and slightly uneven surface. Almost as soon as the thallus develops, it becomes masked by a dusting of equally vivid yellow
soredia—powder-fine granules roughly 25 μm in diameter that contain both the fungal filaments and their green algal partner. Because these soredia are so abundant, the underlying thallus is often all but invisible, and there is no darker fringe at the margins. The consists of tiny, spherical
green algal cells (5–7 μm across) typical of the group. Fruiting bodies (
apothecia) are uncommon but diagnostic when present. They sit directly on the surface () and measure 0.2–0.4 mm in diameter, their slightly darker yellow lying flush with a barely raised rim. The
asci each contain eight colourless
ascospores that are spindle-shaped to rhomboidal with gently rounded ends, usually 18–21 μm long and 5–6 μm wide. No asexual
pycnidia have been observed. A simple chemical
spot test—adding
potassium hydroxide solution—turns both thallus and apothecia a faint red, a reaction that, together with
thin-layer chromatography, confirms the presence of
pulvinic acid pigments responsible for the lichen's intense yellow hue. The sorediate
Candelariella reflexa is somewhat similar in appearance, but can be distinguished from
C. flavosorediata by the smaller size of the granules or areoles comprising the thallus, and by its indistinct soralia and smaller, powdery soredia. ==References==