Naturespeak A naturalist's view of the world

January 20, 2012

Alien vs. Alien

Filed under: Uncategorized — wykes @ 8:35 pm

I saw aliens fighting the other day. A statement like that might seem a bit suspect, but please don’t start backing away. I will not follow up by declaring that the aliens were fighting over the opportunity to probe me. No, these were real aliens – as in “non-native” – plants going at it with gusto. The fight was neither epic nor particularly dynamic, however. In fact, this fight was in such extreme slow motion that it could easily be mistaken as wood sculpture.

The combatants were a Smooth Buckthorn and an Oriental Bittersweet. They were so tightly intertwined that their flesh was nearly one. The good news is that at least one of them will die when this is done. In the best case scenario they both die. Either way, we are presented with a metaphor in this mingling of woods: two bad plants attempting to strangle each other in their quest to squeeze out the native flora.

To be completely fair about it, the Bittersweet vine in this scenario is the more aggressive of the two aggressors. This is the one entangling the “innocent” Buckthorn in its selfish mission to reach the sun.  This is what they do – to great excess and success (often pulling down lesser trees through sheer weight). There are two kinds of Bittersweet to be found in the Midwest. As you might have guessed, the American Bittersweet is the native and the Oriental type is the invader originating from Eastern Asia. Since the 1860’s they have been advancing westward and pushing the native variety out of the way. In short they are better at being Bittersweets than the American Bittersweets.

Their advance has been subtle because the invading aliens look very much like the natives (which makes for the typical plot device in outer space alien invasion movies). No one knows they have moved into the house next door until it’s too late. Both are climbing vines which produce brilliant red fruits surrounded with papery capsules that open and peel back.**

The strangling victim here is not a plant that needs any pity. It too is an alien hailing from Europe. There are two different kinds of Buckthorn here in the Midwest and both have boldly taken over our native woods. These shrubby trees grow so densely in some spots that they form impenetrable thickets and they out-compete other native plants for precious water, sunlight, and nutrient resources.  They choke out rivals through starvation rather than entwinement.  Perhaps their only endearing factor is that birds will eat the berries (even though they may not “like” them).

It is likely that the Bittersweet has already won this particular battle already.  You can see that the vine has cut deeply into the Buckthorn’s bark (see below and detail here) . The water and nutrient flow of the Buckthorn is cut-off as if the Bittersweet had taken an axe and girdled it. It is at the “agh…eck…eek” stage of strangulation. The conquering vine will dance on the bones of the dead tree for many years to come.

The surrounding buckthorns will probably get their revenge, however, as they strive to shade out the Bittersweet and deprive it of sustenance.  Thus the aliens duke it out here on earth and we home-soil  mortals are often reduced to mere observers in the process.

* *American Bittersweets have orange capsules and slightly larger berries than the Oriental Bittersweets which have yellow capsules. These capsules tend to fall off as winter advances, so this is not the best of traits. One look at the placement of the fruits will immediately separate the two: Americans produce a cluster of berries at the end of each stem, whereas the aliens produce small clusters that are equally spaced along the stem.   This pictured plant is definitely the alien species. This has been a public service announcement. Thank  you.

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