Guayule (Parthenium argentatum A. Gray) research 1907–2026: A bibliometric analysis of a recurrently reactivated research field

Natural rubber is a strategic biopolymer, yet the world depends on one tropical species, Hevea brasiliensis Müll. Arg. Genetic uniformity, South American leaf blight, price volatility, and Type-I latex allergy make that dependence fragile and have sustained a century of interest in guayule ( Parthenium argentatum A. Gray). This Chihuahuan Desert shrub remains outside mainstream production. The published guayule research record has never been characterized quantitatively. We analyzed 1,024 documents from 1907 to 2026, retrieved from Scopus and the Web of Science Core Collection, with screening reported under PRISMA 2020. Research output is not a growth curve, but three externally driven waves separated by near-total dormancy, following the wartime Emergency Rubber Project, the oil-shock revival, and the current bio-economy era; a logistic model explains under half the variance in annual output. Authorship is concentrated; one investigator accounts for 10.1% of the corpus and 64.0% of authors publish once. The collaboration network is highly fragmented (modularity 0.850 versus 0.385 for a null model), whereas the intellectual base resolves into five co-citation traditions, so each revival returns to a shared canon rather than a continuing community. Citation attention is inverted relative to the commercialization bottleneck: upstream biochemistry and materials studies attract 1.46 times the year-normalized citations of downstream agronomy and processing. Research is weakly connected to Mexico, the crop's center of origin. The bibliometric evidence suggests that commercialization is constrained less by gaps in biological understanding than by agronomic, biorefinery-integration, and structural challenges. Above all, institutional continuity is needed to translate existing knowledge into production.