Chrysothrix Candelaris, Gold Dust Lichen

Day 100: You might mistake Chrysothrix candelaris for a smear of paint when you first notice it on a trailside tree, but in fact it is a lichen commonly called "Gold Dust." It occurs most frequently on bark, but also occasionally on rock. A hand lens will show that it is comprised entirely of tiny sorediate particles, truly resembling the dust from which its common name is derived. A related species (C. chlorina) prefers rock as its substrate, and forms a coarser, thicker crust. Here in the Pacific Northwest, Gold Dust can be found along many shady trails and even on roadside trees, particularly Douglas-fir. Take a closer look when you find it.

Chrysothrix Candelaris, Gold Dust Lichen

Day 101: If you've done any hiking in the Pacific Northwest, you've undoubtedly encountered evergreen trees (notably Douglas Fir) with a strange greenish-gold coating on the bark. If you looked more closely, you probably thought there was nothing particularly noteworthy about it, or if you touched it, you would have found it powdery on the surface, but impossible to wipe off entirely. There your curiosity was likely to have ended, and if you remarked on it at all, you simply said to yourself, "Weird yellow-green dust on a tree, okay" before moving on to showy wildflowers and butterflies in the meadows.

Would it surprise you to know that this is a lichen? Its common name is particularly descriptive: Gold Dust. Note the fir needle just right of center for a size reference. That will give you an idea how fine the texture is. Scientifically, it is known as Chrysothrix candelaris, a reference to its resemblance to another lichen family, the Candelarias.