Ramalina siliquosa Chem. crassa forme des rochers côtiers.

    Thallus small, tuft-forming, more or less erect, to 5-8 cm tall, composed of branches emerging from a common holdfast tightly appressed to the substratum (not black), branches strap-shaped, more or less flattened and sometimes swollen towards the base, 1-5 mm wide, apices pointed or snake tongue-shaped, following dichotomous branching with pointed or hook-shaped apices, surface rough and dotted white, soralia absent, typically cream or ivory when dry, slightly pale grey-greenish when moist. Apothecia rare. Pycnidia numerous, most often embedded in the thallus, hardly verrucose or nodulose. C-, K+ yellow > red, KC+ yellow tinged red, Pd+ yellow-orange (Chem b). This taxon grows on top and walls of very exposed siliceous rocks in the coastal zone, often in large colonies. Seems to be in part the type species of British authors, at least refering to the colour and the common name used: 'Sea  ivory'. May be confused with Ramalina subfarinacea which is sorediate and above all with some forms of Ramalina cuspidata s.l. of which branches are terete and not flattened. N.B. This taxon is linked to Ramalina siliquosa Chem. crassa by its chemical reactions and might be a simple form limited to highly exposed coastal rocks.*