Today’s entry was written by BPotD work-study student, Katherine. She writes:
For today’s entry we have two lichens, Cetraria ericetorum and Flavocetraria cucullata. Many thanks to Richard Droker (aka wanderflechten@Flickr) (Daniel adds: I believe the vascular plant in the image is Sedum stenopetalum).
Cetraria lichens are commonly known as Iceland lichens, Icelandmoss, or heath lichens. While Cetraria ericetorum is commonly known as Iceland lichen, Centraria islandica (as inferred by the name) is known as “true Iceland lichen”, according to Brodo et. al.’s 2001 tome, Lichens of North America (hereafter referred to as Brodo, as he was the principal author). The USDA lists two subspecies of Cetraria ericetorum, Cetraria ericetorum subsp. ericetorum (cetraria lichen) and Cetraria ericetorum subsp. reticulata (reticulate cetraria lichen).
In Lichens of North America, Cetraria ericetorum is described as having a pale to dark brown usually-curled thallus (body) with narrow lobes 1-3mm across, which may become fused where the edges touch. However, according to the Lichen Flora of the Greater Sonoran Desert Region Vol. 1, it may be anywhere between 0.5mm and 8.0mm in breadth. Brodo goes on to describe Cetraria ericetorum as growing on the ground with grasses and heath, and, in order “to tell one species of Iceland lichen from another, look for the white pseudocyphellae [= “a tiny white dot or pore caused by a break in the cortex and the extension of medullary hyphae to the surface”] on the branches”.” Furthermore, that “the lobes of [Cetraria ericetorum] are narrower [than Cetraria islandica], and [Cetraria ericetorum] never contains fumarprotocetraric acid”.
The Consortium of North American Lichen Herbaria (linked above re: Sonoran flora) cites that Cetraria ericetorum is found on “soil and moss, or rarely on bark or wood” in “temperate [or] boreal areas of western North America from low altitudes to alpine areas and at high altitudes” (distribution map). Brodo shows a range further northwards into most Canadian provinces, with some gaps in northern Alberta and central Saskatchewan.
The second species present belongs to the genus Flavocetraria. Brodo characterizes them as small to medium-size, with pale greenish yellow to yellow colouring, having a smooth lower surface which is the same colour as the upper surface, without any rhizines or cilia and having white medulla [“internal layer of the thallus or lecanorine apothecium, generally composed of loosely packed fungal hyphae”]. He also notes their resemblance to the genus Cetraria, except for their colour, and note that “several species of Cetraria grow in the same habitat” as evidenced by this photo of the two growing together.
Flavocetraria cucullata may be “2-6 (-8) mm wide and 25-60(-80) mm high, ruffled at the margins, and curled inward, almost forming a tube (sometime fusing where the edges touch), often curving back at the tips […] the base of thallus [may often become] red-violet”. The species is found “on the ground among mosses and heath” and “in open conifer woodlands and tundra, usually at high elevations”. Brodo also reports that Alaskan indigenous peoples incorporated this lichen as a flavouring for fish or duck soups.
The distribution map for Flavocetraria cullata is available via from the Consortium of North American Lichen Herbaria.
DigitalMycology.com provides several photographs which may help for distinguishing between Flavocetraria cucullata and Flavocetraria nivalis, a very similar looking lichen: Flavocetraria.