A Grammatical Dictionary of Botanical Latin

caesius,-a,-um (adj.A), superl. caesissimus, very intense blue: lavender blue (often applied by Romans to blue eyes); bluish or bluish-glaucous; greenish pruinose; having a blue color very low in chroma; “lavender color” (Lindley); “light grey, bluish or glaucous blue” (Magill 1990); "covered with a thin, opaque, greenish deposit (bloom) of macroscopically indistinguishable waxy particles that rubs off easily (Kiger & Porter 2001); caesios oculos Minervae, (acc. pl.) the blue-gray eyes of Minerva; related to caelum,-i (s.n.II), abl. sg. caelo: the sky, the heavens; = glaucous, q.v.; see bloom.

- [lichen] thallus niger, interdum caesio-cinerascens (Nyl.), thallus grayed black, sometimes a light bluish-ashen gray.

- [lichen] thallus niger, interdum nonnihil caesio-pruinosus, glebuloso-congestus (Nyl.) the thallus dull black, sometimes somewhat [lavender-]blue-bloom, densely glebulose [i.e. with rounded elevations].

- [P. lurida] recens ac humida disco albido-caesia vel incana, margine subtusque ex ochreo fuscescens (s&A), fresh and moist, with the disk whitish-caesius [i.e. blue, gray-blue] or grayish-white, at the margin [and below] darkening [i.e. becoming grayish-brown] from ochreous [i.e. ochraceous, or yellowish-brown, to fuscescent].