The sigua tree is in bloom now and I’m working on getting an identification for it. It’s one of those hard ones – in the laurel family – and the locals are smart enough not to try to key it out. They just call it a sigua (from Cuba, cigua, meaning a laural tree), never mind that there are two species called sigua, two called sigua blanca (white sigua), and one called siguita (little sigua) as described by Carrasquilla.
But this post is not about the identification of sigua. It is about something this particular sigua is undergoing, something that is a natural part of competition in the neotropics, but which has recently become a cause for some concern. More on that in a bit.
The sigua is the tall dark-leaved tree in the background. Last November & December, I saw flowers on the top of this tree (the light green color to the left on the sigua top), and I knew they were not sigua flowers.
I walked under the tree and looked up.
There they were, white flowers, looking very much like they belong to the Aster family, Asteraceae. [Update: Or maybe not. See comment by The Phytophactor below. Cactaceae? or Ranunculacae? The puzzle of the liana's name, like that of the sigua, remains to be solved.] So I started tracing the branches downward so I could see where the plant originated.
Here you see a branch of the sigua tree running horizontally across the top third of the image. The more or less vertical branches lead down from the flowers.
Still coming down:
Then close to the ground:
And then . . . snaking across the ground:
And more snaking …
To the point where it emerges from its roots:
It’s a marvelous structure.
It’s a liana, which is a woody vine. You’ll see lianas called vines and vines called lianas in the popular press, but the proper usage of liana is for woody vines only.
I’m a little concerned that this liana might damage the sigua. Lianas, I have read, can so overgrow a tree that the leaves of the tree itself cannot get the light they need to photosynthesize. Plus, since they’re rooted in the ground and take water and nutrients from the soil, they compete with the tree’s roots as well.
I went online to find some recent work to support this statement, and I came upon a startling article published just this month at the Smithsonian Tropical Research Institute site: Scientists race to determine why vines are taking over forests in the American tropics.
It seems that:
On Barro Colorado Island in Panama, the proportion of vines in tree crowns has more than doubled over the past 40 years. In French Guiana, liana vines increased 60 percent faster than trees from 1992 to 2002.
The phenomenon is occurring throughout the Neotropics, but the one study reported from the tropics in Africa showed no such thing. (By the way, do visit the link and watch the video. I really enjoyed hearing the reasons why Stefan Schnitzer went into science in the first place, and why he likes it now.)
What to do, what to do. Should I let nature take its course, whatever that may be, or should I protect the sigua, which produces fruits greatly enjoyed by birds?