Bdallophytum americanum.
Every once in a while, we botanists discover things out in nature that, at first glance, appear to defy classification. The present photograph is a case in point. While botanizing in San Luis Potosí, Mexico, I stumbled upon weird little stout spikes up to four inches tall poking out of the ground. What were these? Plant? Fungus? None of the above?
Upon excavation, I found that these organisms were attached to plant roots, which I traced back to a nearby gumbo-limbo tree (in the genus Bursera). Back in the herbarium after the trip, study of library resources and comparison with other specimens revealed that the organism goes by the equally odd scientific name, Bdallophytum americanum.
The three species in the little-seen genus Bdallophytum are, in fact, plants (in the family Cytinaceae), but not just ordinary plants. The germinating seeds drill into the roots of a host tree and create connections called haustoria with the conducting tissue. Bdallophytum produces no chlorophyll and, unlike most plants, does not manufacture its own food through photosynthesis. Instead these freeloaders siphon off a portion of the host’s water and sugars parasitically. Fortunately, their parasitism does not appear to weaken the host enough to cause wilting or other visible decline. What I found in the field was plants with developing fruits capped by the blackened remains of the flowers.
Parasitic plants are limited by where they can find suitable hosts. In the case of Bdallophytum, those hosts are almost always a small suite of tree species in the relatively widespread genus Bursera. Although Bdallophytum grows in seasonally dry woodlands scattered from Central Mexico to Nicaragua, most botanists never encounter it in nature. The plants spend much of their lives underground as a small blob of tissue inside and on the surface of a root, feeding off of their hosts. They only come up for daylight when the urge to reproduce causes them to grow into those odd little inflorescences that I happened to stumble upon.
Want to know more? Check out Dan Nickrent’s wonderful website, The Parasitic Plant Connection at: http://parasiticplants.siu.edu. As a botanist, much of my enthusiasm has been sparked by getting out into nature. It is one thing to read about weird and wonderful creatures or to see specimens preserved in museums such as those in the Billie L. Turner Biodiversity Collections at UT. But, there is nothing that sparks my curiosity and creativity like observing and learning something new to me through chance encounters like these in the wild.
George Yatskievych is a Curator at the Billie L. Turner Plant Resources Center
