Answers are grounded in this paper and cite their sources.
Aaron Liston, William A. Robinson, James M. Oliphant, Elena R. Alvarez-Buylla, Length Variation in the Nuclear Ribosomal DNA Internal Transcribed Spacer Region of Non-Flowering Seed Plants, Systematic Botany, Vol. 21, No. 2 (Apr. - Jun., 1996), pp. 109-120
No takes yet. Share an insight, caveat, or question.
Liston et al. (1996) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: