One of the many highlights of our recent trip was a visit to the Ohoopee Dunes Natural Area near Swainsboro, Georgia, where Dr. Mincy Moffett gave us a tour of this uncommon ecosystem. The Ohoopee Dunes are the most extensive riverine sandhill formation in Georgia, and host a number of rare and threated animal and plant species.

One vignette of the tour was this location where Cladonia evansii, also known as powder-puff lichen or deer moss, was found in abundance. With its dense clusters of greyish-white round tufts, it looked like someone had assembled a collection of miniature tumbleweeds in the oak leaf litter (I think it's bluejack oak, Quercus incana). While we all admired the amount of this lichen in this location, Alan Cressler has a photograph of an even denser stand from a different tract of the Ohoopee Dunes: Cladonia evansii.

In the USA, Cladonia evansii is found along the coastal plain of the eastern seaboard, ranging from Texas to at least North Carolina (and perhaps even further north -- I can't tell on the map I've used). It is also found in the Caribbean. Its habitat preference is partially shaded or open ground, typically in sandy areas. Additional images are available from ForestryImages.org: Cladonia evansii and Sharnoffphotos.com: Cladonia evansii.

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.

...and the "plants of the north" series concludes with an organism (or rather, organisms) without flowers.

A set of links about Thamnolia vermicularis, or whiteworm lichen, since I'm away on vacation:

• Thamnolia vermicularis is not restricted to the northern hemisphere, as explained in The Geography of Phytochemical Races
• additional photographs of Thamnolia vermicularis from the Sharnoffs
• the genus Thamnolia via the Toolik-Arctic Geobotanical Atlas

Methuselah beard lichen or old man's beard lichen (and known often scientifically by its synoynm, Usnea longissima) was once more widespread than it is today. Throughout much of its historic range, a patchy distribution of circumboreal forests in Europe, Asia and North America, it is now either threatened or extirpated. Populations remain strong in the Pacific Northwest of North America, however. Declines are attributable to habitat loss (clear-cutting) and air pollution.

In one of my favourite natural history books, The Lichens of North America, reference is made both to its pollution-sensitivity: "Its presence can be used as an indication of pure air" as well as its outstanding potential length: up to 3m (10ft) ("easily the longest lichen in the world").

A photographic note: the vertical streaks in the background of the image are rain drops.

Nebulagirl posted today's Botany Photo of the Day in our Flickr Pool two weeks ago. She included a number of great shots in addition to this close-up, all of which you can access here. Of course, we extend our thanks to nebulagirl for this opportunity to take down and dust off our old lichen-related volumes.

Cladonia cristatella is just one of the planet's over 14000 lichen species. Unlike most plants, lichens are composite organisms; they develop, that is, from a symbiotic association between a unique fungal species and a photosynthetic partner (often green alga or cyanobacteria). They have no hydration apparatus, and this allows them to excel in conditions and habitats fatal to most other plants (deserts, arctic tundra, bare rock and sterile soil). Lichen species' capacity to adapt to the labile complexion of their surrounding environment is perhaps best demonstrated by their ability to enter metabolic suspension (dormancy) in order to survive desiccation in periods of intense water deprivation, proceeding to rehydrate and thrive when a supply of water again becomes available. Though they often grow on other plant specimens, lichens are not parasitic, and they have little, if any, adverse affect upon their host; some species, particularly those in the subgenus Cladina, do, however, emit into the soil chemicals that inhibit, or even preclude, the growth of competing plants. Historically, parts and extracts from lichens have served as ingredients in dyes and perfumes, and they have been thought effective treatments for lung disease and rabies. Generally speaking, humans have not made standard fare of lichens, as most species have a bitter taste and little nutritional value.

In today's photo, Cladonia cristatella (British soldier lichen) seems to ooze from its decaying woody host like fresh magma bubbling up from the coarse veins of the ocean floor. The species joins the Cladonia fungus and the Trebouxia erici alga. A thin stalk lifts the red, club-shaped apothecia up to a height of about 25 mm. This is eastern North America's only red-fruited Cladonia species lacking in both soredia and granules (typical reproductive structures). Unlike other lichen species, Cladonia christatella is somewhat tolerant of pollution, and this is why, in urban areas, it is more common than its relatives.

Source:

Brodo, Irwin, Sylvia Duran Sharnoff, and Stephen Sharnoff. Lichens of North America. New Haven: Yale UP, 2001.

I'm on vacation, so please accept my apologies for the brief entries. -- Daniel.

I'm not sure of the identity of this one, but I suspect Cladina rangiferina, or reindeer moss (though it's really a lichen). This was growing at ~850m (2800ft) in elevation. It was a common sight in the White Pass area, although I must admit it does look a bit different when a macro lens is used (see other images of Cladina spp.).

It also seems that all Cladina species are now lumped into Cladonia; the USDA PLANTS database still uses Cladina.

Apologies for the late entries recently – I'm finishing up a big project (that you'll get to see at the end of January or so) and all that goes with that, so opportunities for rest are taken when I can get them.

I'm fairly certain of the identity of this lichen, though it could be another species in the genus. If it is Bryoria fuscescens, its common name is speckled horsehair lichen or pale-footed horsehair lichen. The epithet fuscescens means “becoming dark”. The related Bryoria fremontii is regarded as “the most widely used edible lichen in North America” (see edible horsehair at the Lichens of North America site).

Bryoria fuscescens is widely distributed across North America and Europe, particularly in association with montane and boreal forests. It is commonly found on conifers.

Thank you to Stephen B of Scotland aka stephenbuchan@Flickr for sharing today's photograph (original). I've been wanting to feature this species for a while, so much appreciated, Stephen!

If asked to create a list of familiar organisms by the seashore (and lived in a temperate area), I'm betting that most people would not include “lichen” on the list. Narrowing it down to a list of the organisms in the intertidal (the band of life between the high-tide and low-tide marks), and I'm still willing to bet lichen would be absent from most lists. Mussels, yes. Barnacles, yes. Seastars, likely. Seaweed, yes. Lichen? Not likely, unless you know that the black patch of what looks like oil residue is not what it first appears to be.

Sea tar or black seaside lichen is found along coastal rocky shores throughout much of the temperate parts of the world. In these areas, it is often a component of the upper intertidal zone and, above that, the salt-spray zone. To give a rather unscientific example of how it is overlooked, its near-constant intertidal companion with a similar distribution range, Mytilus edulis (or blue mussel / common mussel) receives nearly 600 000 hits on a popular search engine; Verrucaria maura? Fewer than a thousand.

The UK-based Field Studies Council has a small article about tar lichens in general, and a specific page about Verrucaria maura as well. Through photographs, Seaweeds of Alaska reveals how Verrucaria maura can be seen from the air. A closer photograph of the banding caused by lichens is displayed in a story about lichen study in the Gwaii Haanas National Park Reserve of British Columbia: Time for Nature – Learning About Lichens.

Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel

Brown-eyed wolf lichen is considered one of two species in the genus Letharia (the other being Letharia vulpina). At first glance, it is readily distinguished from its counterpart by the presence of brown apothecia. However, read Susanne Altermann's “A Second Look at Letharia (Th. Fr.) Zahlbr” (PDF) from the Winter 2004 Bulletin of the California Lichen Society for information that suggests the classification of species in the genus might be a bit more complicated than at first glance.

It's been a while since I've shared one of these types of images. Letharia vulpina growing on an old, fallen log of Pinus ponderosa.

Natural history resource link (local): Volker of Surrey, British Columbia recently shared his weblog with me: Haliaeetus. Volker shares his nature and seasonal observations through photography and commentary.

This is a companion image and written entry to a previous BPotD on lichen diversity, though it was photographed three months earlier and 900 km (~550mi) away from the other image. I was pleased to discover lichen-covered rocks in Grasslands National Park, as it was an unexpected photographic dimension in exploring the area; I'd anticipated the skyscapes, the endangered species and the wildflowers, but not the lichen patterns.

In comparison to the crustose lichen-covered rock in the other entry on lichen diversity, I would expect the process of succession to occur over a much larger time scale. Dessication, temperature extremes, wind abrasion and fewer moss and vascular plant colonizers create conditions where the reign of the lichens is unlikely to be toppled for centuries, if not millenia.

On a different topic, I had the opportunity to walk around the garden for a small time yesterday, and noted that spring is tentatively making an appearance. I imagine 2007 photographs will soon start to become common on BPotD.

Two folks from British Columbia contributed today's images, both submitted via BPotD Flickr Group Pool. Lotus J., aka ngawangchodron@Flickr submitted the first image (original image) and Brettf@Flickr submitted the second (original image). Thank you to both of you, much appreciated.

Both photographs demonstrate a member of the genus Cladonia, or cup lichens. One of the distinguishing features of Cladonia is a two-part body consisting of primary thalli and podetia. Primary thalli and podetia are present in both images; the thalli are the “flat little crusty green bits” (most of what can be seen in the first photograph, but not as ubiquitous in the second) while the podetia are the stalked structures. The red parts on the end of some of the podetia are apothecia, a particular type of spore-bearing structure.

Identification of Cladonia can be difficult, and I haven't spent a lot of time attempting to identify the one in the second photograph, though it should be possible with the podetia present. Identifying Cladonia before the podetia are developed, however, is difficult beyond recognizing that it is a Cladonia. As Trevor Goward writes in Plants of Coastal British Columbia: “Though easy to recognize as a group, the cladonia scales are notoriously difficult to identify to species. Still, it can be ‘fun’ trying (consult a technical manual such as Thomson 1967).”

Photography resource link: Photography Locations via The Luminous Landscape. Finding where to photograph can be difficult (especially when travelling), so resources like these are very helpful. I only wish such a thing existed for wildflowers, since this resource concentrates on landscapes.

Updated February 7, 2006 at 4:06pm: Thanks to Doug who suggested some alternatives to my tentative identification in the comments, I went out and re-examined the lichen. I'm now reasonably confident that this is Evernia prunastri and not what I misidentified it as, Platismatia stenophylla. I think it's an opportune time to remind you that I'm more interested in having the correct information available to BPotD readers than I am in being “right”. If I ever post something that doesn't sit right with you or if you can add something (including a different perspective!), please comment – Daniel.

Mysteries abound, today. Let's start with the lichen. I'm fairly certain it is Platismatia stenophylla or ribbon rag lichen, but it's difficult to confirm. I've only one image in a book to compare with, since there are no results in image search engines for either Platismatia stenophylla or a synonym, Cetraria stenophylla. Nope, I was wrong – Evernia prunastri is a better match. This taxon's native range of occurring in coastal forests of temperate western North America matches, as does its property of growing on trees – so perhaps I'm right. To help be certain, I'd have to break out the chemistry kit. As I've noted before, lichen identification is often aided by observing reactions to chemical reagents (if you ever see a person in a forest with a satchel of small bottles covered by eyedroppers, you will have encountered a bona fide lichenologist).

For Platismatia stenophylla Evernia prunastri, confirming that it is either KC+ (yellowish) or KC- would help verify my tentative identification. This test would involve first wetting the thallus (body) of the lichen with a ten percent potassium hydroxide (KOH) solution, or the K test. The C test would be a dose of bleach, that is, a solution of sodium hypochlorite. If there is no apparent reaction to the bleach on the KOH-soaked lichen, another bit of evidence would be in agreement with the identification. If the test was positive, however, the thallus would change colour. For this lichen, a change to a yellowish colour would help confirm. If it changed a different colour, I'd be back to scratching my head over other possibilities.

The Oregon Coalition of Interdisciplinary Databases has a good entry on Evernia prunastri, and image search comparisons also suggest a match.

The hybrid witchhazel poses a different sort of mystery. Occasionally in the past few years, some staff time has been invested in attempting to verify that a cultivar 'Fireglow' exists. So far, we've come up short. Staff from the garden have searched online, reviewed the horticultural literature and even contacted the International Cultivar Registration Authority for Hamamelis, all to no avail. Its existence as a cultivar could be due to something as simple as a clerical error in its thirty year history. Or, perhaps it is a locally-developed selection, named and sold only to a select few three decades ago (it was purchased from a now-closed local nursery). Too, it could be a misidentification and actually an entirely different cultivar. We haven't yet figured it out.

Photography resource link: Tripod Therapy, an article by Rod Barbee for Nature Photographers Online. Good advice regarding one of photography's most important tools.

Elegant sunburst lichen seems to be distributed throughout every province and territory in Canada (the national lichen?), most of the western United States, and parts of the northeastern US and southern Appalachians. According to “Lichens of North America” (ISBN: 0300082495) by Brodo, Sharnoff and Sharnoff, it prefers open rocks rich in nutrients. A bit of perspective is required – an open rock rich in nutrients to a lichen is one that is often “fertilized” with the excreta of birds or mammals. The authors also write that Inuit hunters could use concentrated groupings of the lichen to locate the burrows of hoary marmots. You can read more about this lichen from the authors here, on the site that ties in with the book.

Botany resource link: Two articles today, both on the same subject and written by Dr. David Hershey on ActionBioscience.org – Avoid Misconceptions When Teaching about Plants and More Misconceptions to Avoid When Teaching about Plants. I read both with an eye to seeing if I'd propagated any misconceptions, and I think I've avoided any of these pitfalls so far.

The boulder beneath this miniature jungle was part of the same rock slide as the rock in the BPotD entry on lichen diversity, yet it supports different organisms. Unlike the dome-shaped rock less than 10m away that was covered by the crustose lichens, this boulder has crevasses and depressions which accumulate water, air-borne dust and organic material at a comparatively rapid rate. After forty years, this boulder is not only blanketed by these non-vascular organisms (roadside rock moss, pixie cup lichen and club cladonia), but some vascular plants have started to colonize it as well: parsley fern, grasses and saxifrages – a small-scale example of ecological succession.

Botany resource link: Native American Ethnobotany database from the University of Michigan - Dearborn. “A Database of Foods, Drugs, Dyes and Fibers of Native American Peoples, Derived from Plants.”