Here's an email i recieved from
B. Eugene Wofford, Director of the Herbarium
your shrub is trifoliate orange (poncirus trifoliata); it is an introduced
species and has been used as a security fence with its sharp persistent
thorns; the fruit is very tart and inedible, at least to me. you can view
other images on the website below.
Hepaticaciously,
B. Eugene Wofford, Director of the Herbarium
Dept. of Ecology & Evolutionary Biology
442 Hesler Biology Building
The University of Tennessee, Knoxville,TN 37996
bewofford@utk.edu; 865-974-6212
Herbarium website: https://tenn.bio.utk.edu/vascular/
Thanks for helping ... Perfekt