Biological invasions have become a worldwide problem, and measures to efficiently prevent and control invasions are still in development. Like many other parts of the world, China is undergoing a dramatic increase in plant invasions. Most of the currently 933 established (i.e., naturalized) plant species, of which 214 are categorized as invasive, have been introduced into China for cultivation. It is likely that many of those species are still being traded, particularly online, by plant nurseries. However, studies assessing whether naturalized and invasive species are currently being traded more or less than nonnaturalized aliens are rare. We extracted online‐trade information for 13,718 cultivated alien plant taxa on 1688.com, the largest website for domestic B2B in China. We analyzed how the presence in online‐nursery catalogs, the number of online nurseries that offerred the species for sale, and the product type (i.e., seeds, live plants and vegetative organs) differed among nonnaturalized, naturalized noninvasive, and invasive species. Compared to nonnaturalized taxa, naturalized noninvasive and invasive taxa were 3.7–5.2 times more likely to be available for purchase. Naturalized noninvasive and invasive taxa were more frequently offered as seeds by online nurseries, whereas nonnaturalized taxa were more frequently offered as live plants. Based on these findings, we propose that, to reduce the further spread of invasive and potentially invasive plants, implementation of plant‐trade regulations and a monitoring system of the online horticultural supply chain will be essential.

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Interactions between alien plants and local enemies in introduced ranges may determine plant invasion success. However, little is known about whether herbivory-induced responses are transmitted across vegetative generations of plants and whether epigenetic changes are involved during this process. In a greenhouse experiment, we examined the effects of herbivory by the generalist herbivore Spodoptera litura on the growth, physiology, biomass allocation and DNA methylation level of the invasive plant Alternanthera philoxeroides in the first- (G1), second- (G2) and third-generation (G3). We also tested the effects of root fragments with different branching orders (i.e., the primary- or secondary-root fragments of taproots) of G1 on offspring performance. Our results showed that G1 herbivory promoted the growth of the plants in G2 that sprouted from the secondary-root fragments of G1 but had a neutral or negative effect on the growth of the plants in G2 from the primary-root fragments. The growth of plants in G3 was significantly reduced by G3 herbivory but not affected by G1 herbivory. Plants in G1 exhibited a higher level of DNA methylation when they were damaged by herbivores than when they were not, while neither plants in G2 nor G3 showed herbivory-induced changes in DNA methylation. Overall, the herbivory-induced growth response within one vegetative generation may represent the rapid acclimatization of A. philoxeroides to the unpredictable generalist herbivores in the introduced ranges. Herbivory-induced trans-generational effects may be transient for clonal offspring of A. philoxeroides, which can be influenced by the branching order of taproots, but be less characterized by DNA methylation.

Interactions between alien plants and the newly emerging enemies in introduced ranges may determine plant invasion success. However, little is known about whether herbivory-induced responses are transmitted across vegetative generations of plants, and whether epigenetic changes are involved during this process. In a greenhouse experiment, we examined the effects of current, parental and/or grand-parental herbivory by the generalist herbivore Spodoptera litura on the growth, physiology, and biomass allocation, and the status of DNA methylation of the first-, second- and/or third-generation clonal offspring of the invasive plant Alternanthera philoxeroides, which were derived from two types of root fragments with different branching orders (i.e., the primary- or secondary-root fragments of taproots). Parental herbivory promoted the growth of the second-generation plants sprouted from the secondary-root fragments, but had a neutral or negative effect on the growth of the second-generation plants from the primary-root fragments. The growth of the third-generation plants was significantly reduced by current herbivory, but not affected by grand-parental herbivory. The first-generation plants exhibited a higher level of DNA methylation when they were grazed by herbivores than when they were not, while neither the second-generation nor the third-generation plants showed the herbivory-mediated changes in DNA methylation. Overall, the herbivory-induced growth response within one generation may represent rapid acclimatization of A. philoxeroides to the unpredictable generalist herbivores in the introduced ranges. Herbivory-induced trans-generational effects may be transient for clonal offspring of A. philoxeroides, which can be influenced by the branching order of taproots, but be less characterized by DNA methylation.

Interactions between alien plants and the newly emerging enemies in introduced ranges may determine plant invasion success. However, little is known about whether herbivory-induced responses are transmitted across vegetative generations of plants, and whether epigenetic changes are involved during this process. In a greenhouse experiment, we examined the effects of current, parental and/or grand-parental herbivory by the generalist herbivore Spodoptera litura on the growth, physiology, and biomass allocation, and the status of DNA methylation of the first-, second- and/or third-generation clonal offspring of the invasive plant Alternanthera philoxeroides, which were derived from two types of root fragments with different branching orders (i.e., the primary- or secondary-root fragments of taproots). Parental herbivory promoted the growth of the second-generation plants sprouted from the secondary-root fragments, but had a neutral or negative effect on the growth of the second-generation plants from the primary-root fragments. The growth of the third-generation plants was significantly reduced by current herbivory, but not affected by grand-parental herbivory. The first-generation plants exhibited a higher level of DNA methylation when they were grazed by herbivores than when they were not, while neither the second-generation nor the third-generation plants showed the herbivory-mediated changes in DNA methylation. Overall, the herbivory-induced growth response within one generation may represent rapid acclimatization of A. philoxeroides to the unpredictable generalist herbivores in the introduced ranges. Herbivory-induced trans-generational effects may be transient for clonal offspring of A. philoxeroides, which can be influenced by the branching order of taproots, but be less characterized by DNA methylation.