A common weed of Latin America (also naturalized elsewhere in the world) that you’ve almost certainly stepped on. Formerly of the genus Blechum L., which we offed….(see Tripp et al. 2009 ,Taxon). Note the characteristic four sided inflorescences (recapitulating the decussate pattern of vegetative development). The fruits dehisce in an interesting manner…. fracturing placentae, as we have termed it. Pick one up and check it out next time you’re dodging cow patties and walking on weeds.
Wild collected, Mexico, Tripp & Dexter #163 (DUKE); Photo by Erin Tripp