Rock Foam Lichen

Appearance

Thallus: subfruticose, attached by umbilicus (Awasthi, 1991: Wetmore, 1970).
Lobes: to 10 mm or long, much longer than wide, upright, cylindrical, flattened at top, contorted, somewhat branched (Awasthi, 1991; Schultz, Porembski & Büdel, 1999; Swinscow & Krog, 1988; Wetmore, 1970).
Surface: olivaceous to olivaceous brown, sometimes with a thin necral layer (Swinscow & Krog, 1988), lacking both isidia and soredia (Swinscow & Krog, 1988; Wetmore, 1970).
Apothecia: rare, to 0.5 mm diameter, one to several per lobe, immersed (Awasthi, 1991; Wetmore, 1970).
Spores: globose to subglobose, Awasthi (1991) reports measurements of 2-4 x 2-3 μm, while Wetmore (1970) records the spores as 4.5 X 3.0-4.5 µm.

Naming

H.Magn.

Distribution

Arctic; Eurasia Europe; Americas North America (incl Mexico)

Status

G5 Secure
This lichen seems to be declining because there have been no known collections within the past 50 years, although it may have been overlooked (Hinds and Hinds, 2007).
This lichen is listed as regionally extinct on the 2005 Swedish Red List (ArtDatabanken Swedish Species Information Centre).
source: Cyanolichens Index

Habitat

This lichen grows on rocks. It has been found growing along seepage tracks (Schultz, Porembski & Büdel, 1999) as well as on dry exposed rocks (Swinscow & Krog, 1988).
Grows on siliceous rocks of mountain tops and hills (Fryday 2008).