Every time I read about precolumbain agriculture I wonder about how much we don't know and how big the gaps are we need to fill. The idea of huazontle being grown for seeds as well as the leaves is likely part of one gap.
https://en.wikipedia.org/wiki/Chenopodium_berlandieri
Well, a simple google search shows what little we thought was produced was likely over-estimated but it is clear that, however little it was, it wasnt enough to make things happen.
I assume you're talking about Leach's papers. Leach chose a particularly small family of Agaves for his work that also stores less energy per kg, and chose very conservative numbers beyond that. His results, given all that, were unsurprisingly that Agave is just barely worth growing on a caloric basis.
Better estimates are that typical agricultural varieties produced twice as much heart "meat", at more than twice the caloric density he found. It's a much better crop in that light, but it's still not comparable to maize. Agave is also an amazing utility crop (the fibers are good for cloth and rope, the spines for needles, the heart for alcohol), a good border crop to keep animals out, and it's incredibly resilient to climatic conditions that would kill any other crop.
Agave was basically an agricultural insurance policy before global trade networks and financial systems existed. If you were worried that a heatwave or a drought might affect you, you could plant a ton of it on marginal land somewhere and leave it alone for years until you needed it.
Agave is both the scientific genus name and the common English name of the organism (which happens a lot). If it's used in a scientific context (such as a paper) you'd capitalize (the scientific name). In an article for people outside of the field you'd use lowercase (the common name).
Another example would be Boa constrictor. It's common name is the same, but lower case. So a newspaper article uses lower case, a herpetologist upper cases the Boa.
