We lived in San Antonio for much of the 1980’s. I loved the semi-tropical flora, but had scant actual knowledge of the species, etc.
While there, we once had a low of 11 degrees F. - and the mercury stayed there. Many palms croaked, including many Washingtonias. I noticed a small palm was untouched. There weren’t many of these small palms.
When we moved to Charlotte in ‘87, I came across a cluster of these same palms on a block in the Myers Park neighborhood. There was a newspaper article about the palms and the homeowners, stating that they survived -5 degrees F. in 1984 (they were planted in the 1960’s). They called them Windmill Palms. I put 2 and 2 together, did some library research, and learned they are the hardiest trunked palms in the world, and would survive here.
And then in ‘92, I went to K-Mart, and bought two for my yard.