Rock Tripe Lichens, a Limited Guide
First published: 24 November 2021 not copyrighted, use as you wish Michael Papay
Most Recent Update: 27 September 2022
I have learned more about the Rock Tripe Family, and offer this limited guide to identifying some of them. Descriptions are for mature/large thalli.
Upper Surface adorned by raised wart-like protuberances - Lasallia species
- Lasallia papulosa (1) upper surface when dry in shades of gray, although the range of colors possible includes white, lavender, orange, near yellow; also, upper surface crowdedly adorned with raised wart-like protuberances; (2) underside is tan to gray or gray-brown whether damp or dry; (3) thallus mostly flat against the rock surface https://www.inaturalist.org/observations/100618252
- Lasallia pennsylvanica (1) upper surface when dry a nearly uniform dull brown to dark brown ; also upper surface usually somewhat sparsley adorned (not crowdedly packed) with raised wart-like protuberances; upper surface usually wrinkled like a scrunched-up carpet; when damp the upper surface is dull pea-green to brown-green that looks almost greasy; (2) underside is black-to-dark brown [becomes dull brown with age when the black cells have worn away; recognition of the color range of the underside consolidates observations with upper surface color and texture as described above]
Ornamented-Surface Umbilicaria
- Umbilicaria muhlenbergii (1) upper surface adorned by sunken dimples, especially at periphery, and the dimples are where black reproductive structures (apothecia in lichenological terms) are produced; almost unfailingly a very dark brown lichen when dry, and green when damp; (2) underside coarsely textured at the periphery (not a uniform fine-grained near planar surface) (3) black apothecia (reproductive structures) are produced in sunken dimples at the periphery of the thallus https://www.inaturalist.org/taxa/504634-Umbilicaria-muhlenbergii
- Umbilicaria phaea (1) Upper surface smooth and entire, (if surface is fissured, the fissures are at the periphery of the thallus whilst the central area of the thallus is smooth), (lacks sunken dimples or raised warts), is dark brown when dry (like U. muhlenbergii ), and is adorned with black flat (usually), geometric in outline structures (apothecia) with concentric geometric lines within https://www.inaturalist.org/taxa/125055-Umbilicaria-phaea
- Umbilicaria torrefacta (1) Upper surface smooth but fissured like a sort of jigsaw puzzle of melded piece akin to fault lines at junctures of continental plates (lacks sunken dimples or raised warts), is usually dark brown when dry, but color can include frosty tans to white (like U. muhlenbergii ), and is adorned with black flat (usually), geometric in outline structures (apothecia) with concentric geometric lines within https://www.inaturalist.org/taxa/233255-Umbilicaria-torrefacta NOTE: Not always morphologically nor chemically distinct from Umbilicaria hyperborea.
- Umbilicaria hyperborea (1) Upper surface distinctly and abundantly blistered, otherwise somewhat similar to Umbilicaria phaea NOTE: Not always morphologically nor chemically distinct from Umbilicara torrefacta.
Smooth-surface, un-adorned Umbilicaria (Upper surface smooth: not adorned with numerous raised wart-like protuberances, nor with sunken dimples, nor with tiny raised dots)
- Umbilicaria mammulata Two color forms identifiable when dry: (a) the common dark tan to brown to dark brown; (b) the less common near-white, being light tan at the periphery and near-white at the center. (1) upper surface when hydrated is green, when dry is brown to tan to near-white; outline of lichen usually irregular in shape; thallus lobes unequal, the larger lobes actively fold over the main thallus in dry conditions, and unfurl in damp conditions (2) underside black, very fine-grained ( very short false rhizines) (3) the black apothecia (reproductive structures) are spheroidal and occur on top of the upper surface, are not in sunken dimples nor slightly impressed into the surface https://www.inaturalist.org/observations/136615751
- Umbilicaria americana (1) upper surface when damp is light-green, drying to very white; surface at periphery sometimes peppered with small black dots; outline of intact lichen roughly circular, peripheral lobes regular in shape, usually only shallowly incised; (2) lower surface usually adorned with a thick short false rhizines [rhizine is a technical term for what are effectively roots of a lichen], giving the lower surface a somewhat shaggy appearance. Umbilicaria americana is known from non-acidic rocks, usually limestone or dolostone, but amphibolite and any non-acidic rock might, in theory, do. https://www.inaturalist.org/taxa/182508-Umbilicaria-americana
- Umbilicaria duesta Small rock tripe lichen, (1) dry surface deep brown, periphery with numerous black dots; upper surface fine granular texture; thalli small, usually crowded, generally curled under at edge and thus sort of ear-shaped, https://www.inaturalist.org/taxa/182503-Umbilicaria-deusta
Dermatocarpon Rock Tripe Lichens (surface peppered with regular small dark dots; thallus thick and the edges smoothly rounded-over, not thin and papery)
- Dermatocarpum miniatum Looks all the world like an Umbilicaria americana except that its surface is peppered regularly throughout with tiny dots, and has a distribution into warm climates like Texas. https://www.inaturalist.org/taxa/154129-Dermatocarpon-miniatum
- Dermatocarpon muhlenbergii A small, often crowded Dermatocarpon on sun-exposed rocks, although it can survive in woodland shade. https://www.inaturalist.org/observations/100096544
- Dermatocarpon intestiniforme Very small Dermatocarpon, thalli as a group give the appearance of a small mass of intestines; Its presence is indicative of near neutral pH rocks, such as amphibolite. https://www.inaturalist.org/observations/100096761 https://www.inaturalist.org/observations/100618368
A VERY HELPFUL PICTORIAL GUIDE : https://www.waysofenlichenment.net/lichens/Umbilicaria/
