Excerpts from Jim Conrad's
Naturalist Newsletter

Mendez's Sandmat, EUPHORBIA MENDEZII

from the January 16, 2011 Newsletter issued from Hacienda Chichen Resort beside Chichén Itzá Ruins, central Yucatán, MÉXICO; limestone bedrock,elevation ~39m (~128ft), ~N20.676°, ~W88.569°
LIVING WITH LOTS OF SUNSHINE

*UPDATE: In 2025, with many more ID resources on the Internet, I see that in 2011 I mistook this Euphorbia for a form of the worldwide tropical weed E. prostrata. When our pictures were uploaded to iNaturalist, user "nathataylor," working on his PhD studying this sandmat section of Euphorbia, recognized our plant as Mendez's Sandmat, EUPHORBIA MENDEZII, occurring in most of Mexico, Guatemala, southern Florida and here and there in the Caribbean.
The little plant shown above survives at the hot, exposed edges of our asphalt roads. It's the (see sidebar), somehow sprouting up through asphalt at the road's edge. You can judge from the rusty bottle-cap at the top, right that the plant's leaves and flowers are exceedingly small, the leaves averaging about 1/5th inch long (5mm). A close-up of some leaves with a red fruiting capsule at the picture's top is shown below:

Mendez's Sandmat, EUPHORBIA MENDEZII, hairy capsule and red leaves

I needed to see that fruiting capsule, which is only about 1/20th inch high (1.4mm) because those stiff, white hairs arising from the fruit's three corners distinguish the species from similar relatives.

Pictures of Euphorbias are plentiful on the Internet but I find none as reddish as ours. The redness results from long hours of intense sunlight. Often you see plants that normally are green acquire a reddish color when overexposed to sunlight, for red pigment absorbs sunlight energy that might otherwise damage the plant's relatively fragile green chlorophyll.

Also our plant's pairs of leaves occur along the stems much closer together than normal. This is another adaptation to intense sunlight, the closer-together leaves tending to shade one another.

Up North members of the genus Euphorbia often are referred to as spurges, and a field mark helping us recognize them is that they issue a milky, acrid juice from wounded parts. You can see a freshly broken stem below:

Mendez's Sandmat, EUPHORBIA MENDEZII, latex issuing from broken stem