Many believe that though Mesquite may have been on the southern plains practically forever, it was the cattle drives out of Mexico and Texas that greatly spread the Mesquite. Ranchers and the cattle industry in general also affected the spread or rather density because a cow will eat mesquite beans when grass is scarce. How does the spread of a tree species and cattle drives relate? Well, the Mesquite seed has a very hard outer shell that requires "scarification" - abrasion of the outer shell for it to germinate. The digestive system of a cow (or other things that eat the bean) breaks down the seeds hard outer shell and allows it to germinate. Of course other animals could ingest mesquite beans as well and that could account for their gradual spread. I am simply saying that the cattle drives, which were extensive, greatly spread the tree from south Texas to a lot of other areas.
This is probably why the woman said what she said, but she overstated it and was wrong. I am sure the buffalo also played a role in the spread of the tree.
