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Results tagged “june-25”

Jun 25, 2012: Pilophorus acicularis

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!

Jun 25, 2009: Colocasia esculenta

Colocasia esculenta

Colocasia esculenta is widely cultivated in the tropics and subtropics for its starchy edible corms and nutritious leaves. It is believed to be one of the earliest crops cultivated by humans. The origin of the species is uncertain, but it is presumed to be southeast Asia, the home of all other species in the genus. Evidence indicates cultivation in tropical India as early as 5000 BCE. From there its use spread westward to Egypt and the Mediterranean.

The comestible crop was also very important to Pacific Islanders. Cultivation in Hawaii led to the selection of over 150 varieties, including several used for the production of poi—a fermented paste of the cooked corms. Colocasia species contain toxic calcium oxalate crystals, which must be removed by soaking or cooking.

The large, peltate, heart-shaped leaves glow in the setting sun in today's image. Leaves of C. esculenta can grow to 60 cm on plants that reach 1 to 2 m tall. Many variations of colour and form have been developed by a long history of cultivation, lending to the plants frequent ornamental use in modern day gardens. It is a returning perennial in zones 8b and 9, an evergreen perennial in its native tropical climate, and enjoys full sun or partial shade along with copious amounts of water. Here in Vancouver, the plant would not survive the cool winter, but each year it grows from its corms, which are lifted and stored in the fall.


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