Florida's Native Shamrocks

Aye and begorrah - Saint Patrick’s Day is upon us, as are all things green. Whether or not you choose to indulge in a green beer is your call, but one thing that will be nearly impossible to avoid today are shamrocks.

Medicago lupulina (Black medick)
is one of the four "shamrocks"
commonly worn in Ireland
For starters, shamrocks are neither part sham nor part rock, so what's with the name? The Irish word for clover is seamair, and its diminutive is seamróg; an American ear will hear this as shamrock. Incidentally, shamrocks are registered as a trademark by the Irish government.

So now that we're past the etymology, what genus and species of plant is this "little clover"? Apparently, not even the Irish have reached a consensus about this. A 1988 survey conducted at the National Botanic Gardens in Dublin revealed that when the Irish wear the "shamrock," it can be any one of four different plants (none of which are Florida natives), including Black medick (Medicago lupulina) and three different species of Trifolium. As if that wasn't enough, a number of members of the Oxalis (Woodsorrel) family are also worn as shamrocks.

Trifoliate leaves have three leaflets
How did they all come to be considered shamrocks? That's easy - they're all trifoliate, or, in layman's terms, their leaves are compound and contain three leaflets (see image at right). The significance of the number three is believed to be rooted in the Christian doctrine of the Trinity, which Saint Patrick is said to have demonstrated by pointing to a shamrock, whose three leaves are united by a common stalk. Religion aside, we're talking plants on this blog, so let's leave that one alone.

Since we've already established that there is no "Real McCoy" species of shamrock, I think it's fair to say that Florida has at least four native shamrocks:
- Trifolium carolinianum (Carolina Clover)
Trifolium reflexum, Buffalo Clover
- Oxalis macrantha (Tufted Yellow Woodsorrel)
- Trifolium reflexum (Buffalo Clover)
- Oxalis corniculata (Common Yellow or Creeping Woodsorrel)

Carolina Clover is only found in the north portions of the state, and Tufted Yellow Woodsorrel is limited further to the northwest part of the panhandle. As for Buffalo Clover - I'm stumped. Either we haven't been looking for it hard enough or it is extremely picky about where it will grow. There are vouchered specimens from only five of Florida's 67 counties, and only two of the five are adjacent to one another.

Oxalis corniculata (Common Yellow
or Creeping Woodsorrel), a FL native,
can be found throughout the state
The Common Yellow Woodsorrel is, you guessed it, the most common of all of them, and can be found in almost every county in the state (and all over my backyard). It is a facultative upland plant with cheerful flowers that bloom year round. It stays low to the ground, produces a capsule that explodes with seed, and tends to root at its nodes. Bees seem to adore it, so if you are allergic and don't have an epipen within reach, you might want to forgo rolling around in it. Another bit'o'info that's worthy of mentioning - although both Oxalis corniculata and Oxalis macrantha are said to be edible, they contain oxalate compounds that, if eaten in large quantities, can be toxic to livestock.

So... If you think you see a leprechaun in the Sunshine State today, you might want to check in with your optometrist, but if you see something gold at the end of a rainbow, it might just be a field of Florida's most common shamrock.


Unknown said…
Great article! I think I have seen the Buffalo Clover before but now I will looking for it:)
Thanks! The counties wherein vouchered specimens of Buffalo Clover have been found are Alachua, Calhoun, Jackson, Leon, and Polk - if you live in one of these places it's very possible that you've seen it! Keep your eyes peeled and enjoy the rest of your day.
PeteJohnson said…
What I believe to be pink woodsorrel (O. debilis) is blooming in my Duval Co backyard, but have not verified it to species. It seems to be able to grow under large oak trees and up through heavy leaf litter that collects overwinter and into spring. It also seems to come in before full leaf-out of the trees, and/or find spots where sunlight gets through the trees.
Pete Johnson
Hey Pete! Thanks for sharing! That particular species is native to South America and several countries in the Caribbean. I wouldn't be surprised if it's exactly what you have. Unlike O. corniculata, which primarily spreads by seed, O. debilis has bulbils that can remain dormant in the soil for some time. I just checked with the Atlas of Florida Vascular Plants, and O. debilis is definitely listed as being present in Duval Co. There are also a handful of photos that accompany the species page, which may be of assistance in confirming the identity of your specimen(s). Here's the link, in case you're interested: http://florida.plantatlas.usf.edu/Plant.aspx?id=1641
Anonymous said…
Great. Here I was, thinking I had lots of _native_ oxalis growing in my yard, and it's apparently yet another alien. All those cute pink flowers, when the natives are yellow.


... Tom Register
The Jolly Bloggers said…
Sorry, Tom. Knowledge is power?

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