John and George this week indulged their multi-week fixation on the Savannas Preserve State Park and neighboring scrublands. Yesterday we were working on the railroad all the live-long day. Railroad tracks are interesting botanically, because the rights-of-way have been there a long time as unintended plant refuges, and because choo-choos spread species. The floral beauty this week is stunning with yellows coming from Goldenrods, Crotalarias (not necessarily native), and weird little Neptunia. Butterfly Pea (Centrosema virginiana) was so abundant and so gorgeously blue-violet to surpass the average flower garden. Giant Foxtail Grass (Setaria magna) was swaying in the breeze with the bristly inflorescence actually the size of a fox’s tail.
But the great encounters were all three “important” Agave species growing untended in Florida. Agaves are about as fascinating as they are beautiful, with a complex history in human affairs.
First on the list is an abundant but definitely non-native Agave. Florida once was a hotbed of research on fiber plants, one of them being Agave sisalana, the source of commercial sisal fibers, as in ropes, doormats, and similar rough-scratchy commodities. Agave sisalana is still with us in scrubby places. It is the only common Agave in natural areas having no (or few, small, and irregular) prickles along the margins of mature leaves. Recognize this species from the distance by its straight narrow leaves with comparatively parallel margins. Agave sisalana is a Florida Exotic Pest Plant Council Category II invasive exotic, which raises a question, how can a seedless species invade?
That’s easy: Agave sisalana, like most agaves, forms “bulbils” in its maturing inflorescence. Bulbils are baby clones of the parent plant; they represent vegetative reproduction and do not grow from sprouting seeds. Neither fruits nor seeds are known in A. sisalana. The bulbils are tougher than nails, and can float and can last forever unrooted; they are the “perfect” propagules. Bulbils are useful for humans wanting to cultivate agaves, which has been goin’ on a long time.
Agave remains decorate human excrement on the order of 6000 years old in caves. CLICK and
(Do you think somebody will be examining our leavings 6000 years from now?)
Agave sap burns human flesh (believe me!) to the point of being dangerous to the eyes, yet pre-Europeans served agaves in the kitchen, wrapping food in the waxy cuticle, chewing quids made of the leaves, eating the plant flesh, and sipping the sap in beverages. The last-mentioned practice grew into a Mexican industry. Just ask Jose Cuervo.
Agave fibers are beautiful strong, easily extracted by rotting the flesh off of the leaf, and just plain nice. We’re talking about ancient cordage, hammocks, and fishing gear.
So now a few strands of our story come together. Agaves originated almost certainly in or near Mexico and Texas where human civilization is ancient. The plants were valuable for foods, drinks, and fibers. They are easy to store, move, and plant. This all ties into a big Agave fact. This is important, so listen carefully: multiple named “species” of Agaves are in fact ancient cultivars and hybrids, created and moved around by the hand of people and their canoes. This helps explain the sterility, wacky variation patterns, mixed chromosome numbers, and distributions of some “species,” including the Florida “natives.”
Not proven, but personally I am convinced that that’s the story behind the Agaves distributed among the Caribbean Islands. Ancient Caribbean-dwellers were expert mariners and fisher-persons.
And all this begs a huge inadequately investigated question—a question hobbled by a reluctance among traditional taxonomic botanists to take pre-Columbian civilization into account in assessing modern plant distributions. The question is: how did agaves come to Florida? Possibility 1: The Tex-Mex scrub flora around the Gulf was more or less contiguous with present-day Florida scrub. There are western carry-overs from those times still with us in Florida. Possibility 2: Maybe the indestructible bulbils floated across the Gulf or Caribbean Sea, or maybe seeds fluttered here on the salty breezes. Possibility 3: If humans were growing agaves on Caribbean Islands, couldn’t the canoes have stopped by for a Florida vacation? Or could humans have carried bulbils around the Gulf from Mexico?
The level of involvement of Florida in pre-Columbian Caribbean commerce is not known. Those who wonder how Papayas got here ponder this. Here is an unstudied silly notion: our Florida Agave decipiens resembles the Caribbean Agave karatto. In Flora of North America, botanists James L. Reveal and Wendy Hodgson suspected the history of Agave decipiens to be rooted in human activity: “Agave decipiens might have been introduced from Latin America by Native Americans; it is not otherwise known from the wild. The proliferation of chromosome numbers suggests prolonged human propagation and a probable hybrid origin.”
Agave decipiens is a large Florida endemic recognized by the even and well-developed (although of variable length) bristles fully along the leaf margins. The leaves are almost-straight, with little twists and shape irregularities; the margins not as parallel as in Agave sisalana, which differs further by having no or very few marginal prickles. There can sometimes be a short “trunk” at the base. The species is beautiful and in cultivation, although a glance at Google Images reveals material cultivated under this name to be a little “dubiously identified” at times.
Even prettier is our likewise endemic Agave neglecta. The leaves are broader (> 15 cm) than those of A. decipiens and of A. sisalana, and far more curved. The fine mini-prickles are restricted to the lower half of the leaf margin, As with Agave sisalana, fruits are reportedly not produced. (However, there are specimens with fruits bearing this ID in Florida herbaria—see discussion below. Sterile and fertile plants are possible—this occurs in the similar A. karatto, and could be either most likely cytological variation, or sometimes merely a question of pollination.) The taxonomic King of Agaves, Howard Scott Gentry, as reported in Flora of North America, felt that Agave neglecta resembles Agave weberi cultivated for its fibers. Reveal and Hodgson in FNA suggested, “The plant [A. neglecta] may well be a cultivar of A. sisalana or A. kewensis and represent an ancient introduction from Mexico.” (We do not see the Agave sisalana similarity except for the missing fruits.) Most agaves are pollinated by bats, which begs another question. Do Florida agaves achieve pollination? If pollinated, would the fruitless Agaves make fruits and seeds? I don’t know, probably not, but worth a try with a step-ladder, paint-brush, and a few baggies.