Excerpts from Jim Conrad's
Naturalist Newsletter

from the August 9, 2015 Newsletter issued from Yuxunah, 20 kms southwest of Chichén Itzá Ruins, central Yucatán MÉXICO

This week I accompanied a field trip taken by the month-long ethnobotany workshop being conducted here at Yaxunah's Community Center. The excursion was led by specialists from CICY, Yucatá® state's Center for Scientific Investigation, and during it we came upon the largest Cassava I've ever seen, a woody tree about 15 feet tall (4.5m). Below, you can barely make out its much-branched, scraggly trunks against the forest's cluttered background:

Tree Manioc, Manihot cf. carthaginensis, large plants in wild

A closer look at its bifurcating trunk is shown below:

Tree Manioc, Manihot cf. carthaginensis,woody stems of large plant

NOTE: Later I learn that three wild Manioc species occur in the Yucatan Peninsula. Because of its height I'm guessing that this is MANIHOT CARTHAGINENSIS, which can reach 20m in height (65ft). Another woody species commonly occurring here is the woody Manihot aesculifolia, which the literature says can reach 4m in height (13ft) -- not quite as high as the one in our pictures.
It's hard to believe that such a large plant could be a Cassava until you see the leaves, which are typical Cassava leaves. They formed a canopy a good distance overhead, as shown below:

Tree Manioc, Manihot cf. carthaginensis, leaves of large plant

The ethnobotanist leading the workshop suggests that these plants might have been introduced into the Yucatan Peninsula many years ago, even thousands of years ago, long before Europeans arrived. Other plants such as sweet potatoes and tomatoes made long-distance journeys before Europeans invaded the continent, so it's not unreasonable to conjecture that our Cassavas might have done the same.

The CICY trip leader said he'd seen larger Cassavas, with much thicker stems, and when he showed me how large the underground tuberous root could be, it was about as wide as a car tire.