Close-up of pine vascular trace shown in image to the left. From left to right in this trace would be protoxylem, procambium, and protophloem. Image by Dr. Paul J Schulte (University of Nevada). https://faculty.unlv.edu/schulte/Anatomy/Stems/Stems.html

Close-up of pine vascular trace shown in image to the left. From left to right in this trace would be protoxylem, procambium, and protophloem. Image by Dr. Paul J Schulte (University of Nevada). https://faculty.unlv.edu/schulte/Anatomy/Stems/Stems.html