Cenchrus polystachios (Pennisetum polystachion)

Poaceae, Grass Family

There’s a tropical invasive grass oddly not comfortable it seems in southernmost Florida, and not in northern Florida either, but in a belt a little south of the middle, including Palm Beach County.   

The species is introduced and pesky all over the tropical world from Australia to the Loxahatchee Slough.  It owes its spread to introductions as a pasture fodder, as well as to accidental introductions, such as hitchhiking in hay.   The species came to Florida no doubt among many brought as cow chow, although the place and moment are murky, before 1950. 

Missiongrass is eye-catching, being almost as tall as you are, or taller, with big feathery golden amber seedheads looking  like an image from a beer ad.   Kinda pretty.

The species is an example of the “Africanization of American grasses.”  Long story short, African grasses compete well in the warmer parts of the New World, probably tough and resilient because they are adapted to grazing by huge hungry herbivores.   About 12 important Florida grasses are African natives, including most of the large invasive bullies.

One way for a species to compete well is diversity, but who ever heard of a single species where the chromosome numbers are 18, 36, 45, 48, 52, 53, 54, 56, and 78.  That diversity reflects some form of crazy history. be interesting to know if the Florida population all has the same number of chromosomes, and if those are the same as those in Texas.  Finding out would hint at how many times the grass may have been introduced, and would take a ton of effort.   

What is interesting about all those wacky chromosome numbers is that, without delving  into a lesson on the birds and bees, for  making sperms and eggs, chromosomes generally have to match up in pairs.  That’s screwed up in Missiongrass and for it,  making seeds is not reliable.    The species has at least two workarounds….the grass can grow from fragmented stem pieces which is boring, and more interestingly, its flowers can clone directly into baby plants without that pesky sperm, egg, and embryo sex business, although that sort of trickery is it not (yet) documented in Florida. Keep your eyes open because sometimes the clonal babies start growing conspicuously while still on the parent seed head. 

It would fun to know where the name “mission” came from.   Maybe it was introduced as cattlefeed at a remote mission. Or perhaps the name refers to the grass’s “mission” to spread all over the world.