Alex Eaton-Salners earned a JD degree at UC Berkeley and spent eight years as an associate with the Fish & Richardson law firm. (The firm was founded in 1878 and one of their first clients was Thomas Edison.) Eaton-Salners now serves as a director at Western Digital Corporation, a computer data storage company and hard disk drive manufacturer. Somehow he finds time to create crossword puzzles. Each theme answer in his puzzle today includes four circled letters (denoted by boldface below):
Surfer's destination: WORLDWI
DEWEB
Source of post-toilet training anxiety: B
EDWETTING
Youngest son of Queen Elizabeth II: PRINC
EEDWAR
Great Depression recovery program: N
EWDEAL
"Desert plant suggested by the circled letters" is TUMBLEWEED. Eleven different plant families produce tumbleweeds. Simply put, a tumbleweed is a plant's above-ground portion which matures, dries out and then detaches from the stem or root, often "tumbling away" in the wind.
https://en.wikipedia.org/wiki/TumbleweedIn 1931, yodeler Bob Nolan joined the Rocky Mountaineers, a Western singing group led by Leonard Slye. Three years later, Nolan and Slye formed a new group with Tim Spencer, the Pioneer Trio, which eventually became a quartet known as the Sons Of The Pioneers (and Leonard Slye became Western movie/tv star Roy Rogers). One of their earliest hits was
Tumbling Tumbleweeds, written by Bob Nolan:
https://www.youtube.com/watch?v=JQc5gDXQGIs