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Botany Photo of the Day
In science, beauty. In beauty, science. Daily.

Dolichousnea longissima

Dolichousnea longissima

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.

24 Comments

Meg Bernstein commented:

So graceful!

Marijke commented:

When I see these amazing lichens, I feel like I'm in another world.

Keith commented:

Thank you Daniel. Very beautiful.

Rob commented:

Very nice and delicate. I will watch for it in the forests.

Mary Ann, in Toronto commented:

Gorgeous. I'd love to see this in real life.

Bonnie commented:

Wow, this is totally cool! It doesn't look like a beard to me; more like mohair yarn. Is it as soft as it looks?

Betty commented:

How beautiful! Is this related to the "Spanish Moss" found in parts of Florida?

Anne commented:

The lichen is really beautiful and looks like something I'd knit with, but I'm wondering about the shrub it's on. It looks like a buxus to me but that doesn't seem right. Anyone?

Melissa commented:

I, too, was wondering about a possible relationship with "Spanish Moss." I've lived all over the SE U.S. (S.C., N.C., Ga., Fla.), and it's everywhere, beautiful, but filled with little red bugs. People here bake it to kill the bugs and then decorate indoor and out with it. Read or heard anything yet, Betty?

annie Morgan commented:

Aside from the plant subject alone, this is a very beautiful photograph.

stuart commented:

It may look like Spanish Moss, but it's not at all related. Spanish Moss, Tillandsia usneoides, is a member of the Bromeliaceae, the same family as the pineapple. There is some nominal connection, as the genus of this plant is Usnea, and the specific epithet of Spanish Moss is usneoides. Don't know what that means, though.

Daniel in Princeton commented:

This isn't Spanish Moss (Tillandsia usneoides), which is a bromeliad. But the similarity is such that Spanish Moss is potentially the only vascular plant to be named after a lichen (usneoides means Usnea-like), since Usnea would have been more familiar to Old-World botanists like Linnaeus (who named T. usneoides) than the New World Spanish Moss. Both are quite beautiful components of forests. And both are impressive epiphytes, able to draw moisture and nutrients from the air, and as such grow rootless.
A number of Usnea species do get used as dyes for yarn, although not as yarn itself, the lichens are soft when moist, but get rather hard and brittle when dry.
Thanks for posting the picture, as a grad student studying the interactions between plants and fog, Usnea holds a particularly dear spot in my heart.

Tammy commented:

really beautiful! It startling how much it looks like spanish moss- but softer. Interesting that it's stiff when dry, and used as yarn dye.

Andy MacKinnon commented:

A beautiful photo, that supports the speculation that this lichen or a close associate may have provided the inspiration for tinsel on our Christmas trees.

Daniel Mosquin commented:

Anne, it is likely either a willow (Salix) or a member of the genus Prunus. This was a narrow row of trees growing along the roadside between the road and an open wet meadow where I saw Roosevelt elk the night before.

C.Wick commented:

Daniel, a gorgeous photo! Really makes me want to move up North more and more each day. Our lichens down here in Kansas seem so 'boring' when compaired to these wonders.

elizabeth a airhart commented:

i also live in florida tis not like
the spanish moss draped over our trees
or me if you stand still long enough

i found an intersting site while googling
danwinkler -fine pictures from the land of the
umber dragon bhutons
and a folk tale that this is thoughtt to manifest
itself as human beings to help humans on to the path of wisdom a nice site to visit thank you

kelly commented:

beautiful shot! i'm doing a cultural assessment of a northern bc gitxsan territory area near hazelton,bc and there is plenty of old man's beard growing in the old growth areas. promising thought that it indicates "pure air". i'll be breathing more deeply there from now on. thanks!

Kate commented:

That's soooooo pretty!

Eric Simpson commented:

Beautiful shot, Daniel, and it really highlights the delicacy of the strands. I've spent a fair amount of time in the state and national redwood parks in California, especially Prairie Creek, and the old man's beard can reach astonishing lengths and densities in the riparian areas. It's so much like walking through a fairy wood, that I half expect to see brownies peering through the layered strands from the overhanging branches.

Sam commented:

Lovely

Richard Droker commented:

Lighting, moisture and composition make for a quintessential image of this lichen.

Although Usnea longissima was placed in Dolichousnea by Articus in 2004 my impression is that the change has not been accepted. (Wirtz et al. (2006) looked at Neuropogon and do not agree with Articus (2004) for that group, and they further state "We recommend a conservative approach regarding nomenclatural changes from phylogenetic studies especially at the generic level when few taxa are studied.") The North American Checklist and all recent literature have continued with Usnea longissima.

Harold Benson commented:

Is this plant medicinal....i need a reply.tnx

Daniel Mosquin commented:

Some discussion regarding purported medicinal properties on Wikipedia (and Google Scholar): Usnea.

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