Posted by: Rob Viens | April 10, 2012

A Tangle of Lianas and Epiphytes

On April 10th, Darwin’s entry is rather short and mostly about the logistics of the day. He writes:

“We all started before it was light in high spirits; but 15 miles of heavy sand before we got our breakfast at Addea de St Pedro nearly destroyed the whole chivalrous party. — After another long ride we arrived at our sleeping place, Campos Novos.” (Apr 10)

São Pedro da Aldeia (Darwin’s Addea de St Pedro) is clearly labeled on the map, but the name Campos Novos (“new fields” in Portuguese) is only found as the name of a road (estrada) that runs north from Cape Frio. Somewhere in this vicinity (shown approximately on the map) there must have been a village or estate with this name. If any of my friends in Brazil have any suggestions – I’d love to hear about them!

Macaé excursion – April 10

Map of Darwin's Expedition – April 10. 1832

Over the last couple of days, Darwin had a lot to say about the forest plants.  There are two things in particular that he seemed to be fascinated with – lianas and parasitic plants.

“As the gleams of sunshine penetrate the entangled mass, I was forcibly reminded of the two French engravings after the drawings of Maurice Rugendas & Le Compte de Clavac. — In these is well represented the infinite numbers of lianas & parasitical plants & the contrast of the flourishing trees with the dead & rotten trunks. I was at an utter loss how sufficiently to admire this scene.” (Apr 8)

I love the concept of Darwin being made speechless by the beauty of the vegetation.

Le Compte de Clavac is a mystery to me, however, Maurice Rugenda (aka Johann Moritz Rugendas) was a German painter famous for his New World landscape paintings. In the 1820’s he joined Baron von Langsdorff’s Brazilian expedition (undertaken for the Russian Tsar), and although he ended up leaving the expedition, he stayed and painted  in Brazil for some years. Darwin obviously knew of, and admired, his art.

1827 self-portrait of Johann Moritz Rugendas (from Wikipedia Commons):

Johann Moritz Rugenda

Painting titled “Interior of a Brazilian forest” by “F.C., circa 1820”) – possibly one of the images Darwin referred to?

1820 painting of the Brazilian rainforest

“The few stunted trees were loaded by parasitical plants, amongst which the beauty & delicious fragrance of some of the Orchidelig; were most to be admired.” (Apr 9)

Darwin specifically refers to “lianas” in the forest.  The term liana is a generic term for any tropical vines that grow from the forest floor, up into the canopy of a tree to reach the sunlight.  In effect, they take advantage of the tree’s “hard work” (i.e., growing tall and strong) to compete for the same solar “food” source. Although they don’t “feed” off the tree directly, they do compete for resources and sometimes “strangle” the tree, hence causing it harm.

However, lianas are a benefit to other species in the forest.  They provide a route for animals – from ants to monkeys – to climb to the forest canopy for food or safety. This makes them an integral part of the tropical forest ecosystem.

As a bit of an aside, I remember working at the zoo in Seattle, and how the tropical exhibits all had “artificial” lianas, created to enhance the animal habitat.  They had to be artificial so that they would not break down or die, and they were secured to the walls and trees, so the zoo animals would not get hurt. (Having not grown up with them, they were not as proficient as their wild cousins at navigating the vines without falling.)

“I see by my note book, “wonderful, beautiful flowering parasites” invariably this strikes me as the most novel object in a Tropical forest.” (Apr 9)

I have to wonder is some of the other “flowering parasites” Darwin talks about were actually epiphytes – which along with lianas are quite common in the tropical forest.   Like the term liana, epiphyte (or “air plant”) is a generic term for any plant that lives on another plant without causing it harm. In other words, they may live on the branch of a tree in order to be closer to sunlight, but they do not “feed” off the tree (like a fungus does, for example). They get their food via photosynthesis, and water and nutrients from the air (hence “air plants”). Therefore, they are not parasites. In fact, studies have suggested that they actually benefit the tree’s health, and certainly contribute to the canopy ecosystem.  (Many species of orchids are epiphytic, as are many mosses.)

I’m sure we’ll come back to epiphytes again, but for today a picture of an epiphytes (a tank bromeliad) in the Brazilian forest (from EcoLibrary):

tank bromeliad

Tomorrow – Darwin doesn’t feel so good and ponders the perils of tropical travel… (RJV)

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