Substrate moisture and texture affect germination in Houghton’s goldenrod (Solidago houghtonii), a federally protected Great Lakes endemic plant

Abstract

Rare plants garner significant conservation attention, but many have knowledge gaps associated with their life histories. This missing information presents a substantial hurdle for applied conservation. Houghton’s goldenrod (<i>Solidago houghtonii</i> Torrey &amp; A. Gray [Asteraceae]) is a Great Lakes endemic perennial that is often locally abundant but is limited to a narrow region in Michigan, New York, and Ontario. This species is federally listed in the US as threatened, state listed as threatened in Michigan and endangered in New York, and is a species of special concern in Canada. There may be enough viable <i>S. houghtonii</i> populations to meet the US federal recovery criterion, but more data are needed regarding long-term persistence within and across populations, especially related to successful sexual reproduction—key in most seed plants’ long-term persistence. As part of a range-wide study on the species, we performed greenhouse and field experiments to evaluate the effects of substrate moisture and texture on germination success. In both experimental contexts, we found that <i>S. houghtonii</i> germination significantly increased with increased substrate moisture and smoother substrate texture. In addition, a post hoc exploratory analysis on the effects of disturbance on germination showed higher germination in plots with higher disturbance levels, though this trend was not statistically significant. These results add to the limited life history information available for <i>S. houghtonii</i>. Our findings also suggest that substrate texture may be an easily characterized habitat variable that predicts germination for other species because of its relationship to consistent moisture contact for seeds. Weber JB, Leopold DL. 2023. Substrate moisture and texture affect germination in Houghton’s goldenrod (<i>Solidago houghtonii</i>), a federally protected Great Lakes endemic plant. Native Plants Journal 24(1):33–43.