Excerpts from Jim Conrad's
from the April 7, 2013 Newsletter issued from the Frio
Canyon Nature Education Center in northern Uvalde County, southwestern Texas, on the
southern border of the Edwards Plateau, USA
SLENDER FALSE PENNYROYAL
All two-lipped wildflowers with only two stamens are not members of the Acanthus Family, however. If the stem is square, two leaves arise at each stem node, and the two-lipped blossoms with two stamens arise above a deeply four-lobed ovary, the best bet is that it's a member of the Mint Family. That was the case with the delicate, five-inch tall (12cm) herb found flowering among limestone cobbles strewn by floodwaters into a low terrace alongside the little Dry Frio River, as shown above.
Below is a close-up of a hairy, 5/16ths-inch (8mm) long, pink corolla:
When you recognize a plant as a member of the Mint Family you can't keep yourself from pinching a tiny bit of leaf to see what it smells like. Sometimes you're rewarded with a nice "minty" odor but other times the smell is bad, or there's no odor at all. In this plant's case, the odor was deliciously minty.
Here we have what's sometimes called the Slender False Pennyroyal, HEDEOMA ACINOIDES, a species endemic just to arid northeastern Mexico, a bit of Oklahoma, and Texas. In Texas it's most common in our area, which is the southern border of the Edwards Plateau.
Those of you familiar with eastern North America's American Pennyroyal, Hedeoma pulegioides (thus in the same Mint Family genus, Hedeoma, will find it easy to believe that our cobblestone-growing Slender False Pennyroyal is deliciously fragrant. In fact, I read that sometimes this annual mint is gathered for mint tea. I'm sure that it's a fine tea, but the plant is so pretty and, at least in this area, so uncommonly encountered, that it would be a shame to pick such a plant just for making tea.