Amore e pianto, vivono accanto

Pilophorus acicularis ~ Botany Photo of Day

click image to enlarge/original link


Bryant wrote today’s entry. He scribes:

I would like to thank Brent Miller, aka foliosus@Flickr and Richard Droker, aka wanderflechten@Flickr for today’s photos of Pilophorus acicularis or, commonly, devil’s matchstick (Brent’s image | Richard’s image). The genus Pilophorus is a part of the Cladoniaceae, one of the largest and most common families of lichenized fungi. Pilophorus acicularis is the most common species in its genus, and can be found along the west coast of North America (from north of San Francisco to Alaska) and eastern Eurasia.

The primary thallus, or body of the lichen, is granular and crustose, while the tall stalks (or pseudopodetia) form the fruticose secondary thallus. The stalks are usually over 5mm tall and unbranched, however there may be the occasional fork. The black apothecium, or spore-bearing structure, usually sits atop of each stalk. The photobiont (or algal associate) of Pilophorus acicularis is commonly Trebouxia magna, a species of chlorococcoidal (green and sphere-shaped) algae. More photographs of Pilophorus acicularis and related species may be seen on the excellent Ways of Enlichenment site.

Pilophorus acicularis is saxicolous (colonizes rock), and it is most often found on newly exposed silicate rock surfaces. Part of what makes Pilophorus acicularis such an audacious pioneer is that the thalli can host nitrogen-fixing “factories”, in the form of cephalodia. Cephalodia contain cyanobacteria, which fix nitrogen from the air, and therefore can sustain colonies of Pilophorus acicularis on nitrogen-poor sites, like rock surfaces.

Saxicolous lichens, such as Pilophorus acicularis, play a large role in primary soil formation and primary succession. Once established on a rock surface the hyphae of the crustose primary thallus works its way in between the rock crystals and fragments along microscopic fissure lines. The action of the hyphae expanding and contracting (due to presence/absence of moisture and freezing/thawing) slowly loosens the particles of rock. Also, the hair-like structure of the secondary thallus acts much like a comb, collecting and accumulating dust and other airborne particulate. This accumulated airborne particulate, along with the decaying matter of Pilophorus acicularis itself, provides a more advanced substrate for other species (like mosses) to colonize.

Lichens have always fascinated me. Their strange forms and ability to survive and colonize in the harshest conditions makes them seem like a part of miniature alien landscapes (Pilophorus acicularis being no exception). Perhaps this thought isn’t that far out; see this article from the European Space Agency about a lichen’s journey into space!


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