Early clonal growth helps invasive cordgrass gain ground in southern China
image: This conceptual graphical abstract shows that earlier first ramet emergence is associated with greater ramet production in invasive Spartina alterniflora. The pattern is strongest in low-latitude populations near the equator, suggesting that coordinated clonal traits help the species adapt locally and spread successfully in warmer coastal habitats.
Credit: Xincong Chen and Yihui Zhang
The Core Discovery: How do invasive plants thrive across very different environments once they arrive in a new region? A study in the Journal of Plant Ecology offers a new answer: for the invasive salt-marsh grass Spartina alterniflora, success may depend not only on individual traits, but on how key clonal traits work together. S. alterniflora, native to North America, has spread widely along the coast of China and occupied marshes from the warm south to the cooler north. To understand how the species adapts across this wide gradient, the authors collected seeds from eight populations spanning 21°N to 38°N and grew them in three common gardens located at low, mid and high latitudes. The researchers focused on two traits linked to clonal expansion: the timing of first ramet emergence, which marks when clonal growth begins, and the peak number of ramets produced during the growing season, which reflects clonal performance. The researchers found that plants in the low-latitude garden emerged earlier and produced more ramets than plants grown in the other gardens. They also found a generally negative relationship between the two traits across gardens: plants that started clonal growth earlier tended to produce more ramets. Importantly, populations originating from low latitudes near the equator consistently showed this favorable combination of earlier emergence and greater ramet production. In other words, southern populations were not just growing differently—they were expressing a coordinated clonal strategy that appears especially advantageous under warm southern conditions.
Novelty and Innovation: Most invasion studies evaluate one trait at a time, such as plant height, flowering time or seed output. This study instead asks whether two clonal traits covary in a biologically meaningful way. That shift matters, because adaptation is often shaped by suites of interacting traits rather than isolated characteristics. The work also reveals that the two clonal traits do not respond in exactly the same way. The timing of first ramet emergence showed evidence of population-by-environment differences and was associated with abiotic conditions at the populations’ original sites, indicating an important genetic component. By contrast, peak ramet number appeared to be more strongly influenced by phenotypic plasticity. The strength of the negative relationship between the two traits also changed among the common gardens, showing that environmental context affects how this strategy is expressed. Together, these findings suggest that coordinated clonal traits may help explain why this invader performs so well in some regions. The authors further propose that repeated introductions and genetic admixture in China may have provided the raw genetic variation needed for these advantageous trait combinations to emerge.
Future Implications: The findings highlight clonal trait covariance as an underused but promising lens for understanding how invasive plants adapt across large environmental gradients. For ecologists, the study broadens thinking beyond simple “plasticity versus local adaptation” debates by showing that adaptation can depend on how traits are linked. For invasion biologists, it suggests that clonal growth deserves more attention as a driver of spread and persistence. The study may also have practical implications. Because S. alterniflora appears to rely on different life-history advantages at different latitudes, management strategies may need to be region specific rather than uniform across the entire coast. In southern marshes, where earlier clonal emergence and higher ramet production coincide, phenology-based monitoring may help managers act at the most effective time.
Original source: Chen Xincong, Chen Jingyun, Wu Fujia, Zhang Yihui (2026) Latitudinal variation in clonal trait covariances underlies local adaptation of the invasive Spartina alterniflora at low latitudes in China. J Plant Ecol 19:rtag028. https://doi.org/10.1093/jpe/rtag028
About the Journal
Journal of Plant Ecology (JPE) (https://academic.oup.com/jpe), founded in 2008, is led by Professor Yuanhe Yang (Institute of the Botany, CAS) and Professor Bernhard Schmid (University of Zürich) as Co-Editors-in-Chief. The journal is jointly sponsored by the Botanical Society of China and the Institute of Botany, Chinese Academy of Sciences, and is published by Oxford University Press. According to the latest Journal Citation Reports (JCR), JPE has an impact factor of 4.5 and is ranked in the Q1 quartile in the categories of Ecology, Forestry, and Plant Sciences.