Sidewalk Nature: Mistletoe


Sidewalk nature: mistletoe at my feet.

This was a first. And given the season, I thought maybe the mistletoe had fallen out of someone’s Christmas decor. But after I’d tripped over it, I looked up, waaaay up, and saw a much bigger clump high in an elm, spotlit by late afternoon sun. 


I’ve never noticed mistletoe in our neighborhood, but then again, I am walking farther and farther these days (and nights), and noticing all sorts of interesting things.

But I have a question. Nearly all the mistletoe I’ve seen in Nashville—West Meade, Bellevue, Warner Parks—grows in elms. Why elms? What makes elm such a hospitable host for this hemiparasite of a plant?
Especially considering that one of the common names is “oak mistletoe.” Does Nashville have more elms than oaks? Is it simply a matter of demographics? Most field guides just say this mistletoe grows on “hardwoods” in general. 

The botanical name is Phoradendron leucarpum, and I might be able to remember at least the genus, because it means “tree-thief.” Mistletoe steals from trees: it inserts filaments (haustoria) into tree tissue to siphon water and nutrients. This is in addition to the food mistletoe makes for itself via photosynthesis, and which is where the hemi prefix comes in. A hemi-parasite makes food but steals stuff anyway. In contrast, a full-on parasite takes all requirements from a host, and is utterly dependent.


The little yellow bumps are flowers.

Will my sidewalk clump continue to mature after it has fallen from its host?
Will these flowers morph into round, white berries?
Will a bird eat a berry and poop the sticky seed onto my neighbor’s elm?
Will that elm then sprout fresh mistletoe?

Which brings me to another easy-to-remember etymology: the word mistletoe comes from the words for poop and twig, which, taken together, constitute the natural  propagation method for growing more mistletoe on more trees.

I’ll be keeping my sample to find out.