Chrysobalanus icaco and more Chrysobalanus icaco
Cuscuta pentagona and Smicronyx quadrifer
Vanilla mexicana and nobody
Any veteran of third grade knows how in ecology everything is connected to everything in one pulsating web of life. Well, yea, sorta, okay, maybe, sometimes, but what’s been glimmering this week in John’s and my botany have been species pairs more than ecological networks. So today is the day of twosomes, like these purple cocoplums and white cocoplums immediately side by side with intertwined branches in the Kiplinger Natural Area in Stuart, Florida. Interestingly, the purple-fruited individuals have reddish young leaves in contrast with the absence of reddish foliar hues in the white-fruited individual. I wonder if the white-fruited individuals are marginally less resistant to sun injury.
Pretty, but pairs are boring without dynamics. When it comes to parasites, for example, it takes two to tango. Or, in the case of parasitic Five-Angled Dodder, we should say it takes three. The Dodder sucks the victim’s life juices. But it gets a taste of its own medicine, as there’s a parasite on the parasite. The golden dangler in the photo below is not the Dodder fruit, which is a dry capsule. That dangling pod is the home of the Dodder Weevil.
Dodder is apparently a stingy host, being yellow, stringy, and nutrient-poor, so the weevil larvae migrate from the Dodder into the plant the Dodder is parasitizing to add insult to injury.
Dodder exists in scattered patches, locally not abundant. So how does the Weevil find it? Of course nobody knows exactly, and “the” answer lies in a complex tapestry of signaling and sensing. So let’s do like the politicians and pick one thread out of the intricate mesh and pretend it is the whole truth.
Now we shall oversimplify, extrapolate, and speculate with wild abandon.
The Dodder Weevil is not a prominent topic of research. Perhaps, however, we can glean a hint of insight from a better-studied Weevil, such as the Boll Weevil. What draws Mr. Boll Weevil to the Cotton? Apparently a complex of chemical signals, one being vanillin.
Vanillin as in a vanilla ice cream cone? Yes. Vanillin is best known for coming from the Vanilla Orchid, but the chemical is widespread in the plant world, being related chemically to an amino acid and being a breakdown product of plant tissues, especially wood. Among other signals, pesky bugs use vanillin to find distressed plants, studied most famously in Bark Beetles finding Elm Trees, as well as other insects and their plant “partners.” Vanillin may be useful in insect scent traps.
If vanillin comes from deteriorating wood, why don’t I manufacture the flavor from wood scraps rather than nurturing those pesky Vanilla Orchids? Oh rats, they beat me to it: commercial vanillin flavoring has come, on large or small scales, from various forest and pulp byproducts and even from animal manure already partly broken down thanks to digestion. You could get milk and vanillin for the ice cream from the same cow.
John and I were Weevils this week lured to Vanilla, to a Vanilla Orchid that is. Martin County Ecosystem Project Manager and erstwhile hockey goon Mike Yustin showed us Vanilla mexicana flowering and fruiting in a swamp whose location should not be disclosed. (Ugly people go steal pretty orchids.) This is not the commercial Vanilla species, although there’s resemblance.
Vanilla mexicana ranges naturally from South America to Mexico and the Caribbean. So is it a Florida native? Sources differ, and this is not a very interesting question, given that we’re dealing with a widespread species having microscopic wind-blown seeds. So, sure, probably Vanilla mexicana seeds dust Florida trees.
A more interesting question is, “if Vanilla mexicana is an outlier at the chilly margin of its distribution far from its tropical population center,” and if “Orchids tend toward specialized pollinators,” does this species have a pollinator partner way up north here in Florida? (Remember, today’s theme is ecological pairs.)
Possible answers include, maybe the Orchid is pollinated by a generalized pollinator (not likely, nor much fun to discuss); or perhaps its own special pollinator companion came with it (that would be remarkable); or….in this case other botanists have revealed the probable answer. In 2015 Masters Degree Student R. Narinda showed V. mexicana to be self-pollinated. Partner-free and self-sufficient, this unattached species can roam wherever its seeds might blow and not freeze. The “not freeze” part makes Martin County a reasonable northern margin, at least during some decades.
Good link sent by Pat Bowman