Asexual Propagation Techniques for ex Situ Conservation of Satiny Willow (Salix pellita Anderss.)

Salix pellita (satiny willow) is a state-threatened shrub willow species native to Minnesota, USA, valued for its ornamental potential and its ecological value. Habitat loss has reduced its natural distribution in the United States significantly, prompting the need for effective ex situ conservation strategies using horticultural propagation techniques, likely with limited stock materials. Our study evaluated several asexual propagation techniques to develop a standardized protocol for conserving S. pellita . In substrate evaluations, semihardwood stem cuttings resulted in improved rooting success in 100% perlite (100% rooting) compared with a 50/50 peat/perlite mix (73% rooting) and 100% peat (42% rooting). Cuttings grown in perlite also exhibited increases in root number and length. In the cutting type and auxin treatment experiment, single-node stem cuttings achieved > 80% rooting success regardless of plant growth regulator (auxin) application, whereas leaf cuttings exhibited reduced rooting success (32%–66%) and did not produce shoots. In the population-based rooting trial, plants derived from five geographically distinct populations revealed uniform and high rooting success (97%–100%), although some populations exhibited differences in the number of roots generated. This set of experiments has identified effective substrate choices and viable asexual propagation techniques for S. pellita , even when stock material is limited. A consistent rooting response across distinct populations may indicate species-level uniformity in inducing adventitious root formation on semihardwood stem cuttings, providing practical insights for horticultural conservation and broader management strategies applicable to this taxon and other at-risk plant species.