Solidago canadensis , a Flower or Weed?

Figure 1. Flowers or weeds? S. canadensis is one of the worst exotic weeds in China (A). Yet, farmers grow it as a cut flower (B). Because diploid cytotypes grow faster and flower earlier than other polyploids, all cultivated S. canadensis cytotypes for cut flowers are diploids. We found that diploids are sterile under hot-summer temperature south of 24°C-isotherm range and cultivation of S. canadensis will not lead to naturalization. However, the risk for naturalization increases in regions north of 20ºC-isotherm range. Photo credit: Sheng Qiang. Figure 2. Population of Solidago canadensis in native and introduced range in North America and China, respectively. S. canadensis plants are significantly taller and denser in the introduced range in China (Jiangsu) (A) than in their native range of North America (Pennsylvania, USA) (B). S. canadensis plants often outcompete native plants in invasive habitats and essentially become monoculture-type communities. Photo credit: Sheng Qiang. Figure 3. Dramatic difference in height of Solidago canadensis between native and invasive populations. S. canadensis plants can often be over 4m in height in China (Nanjing) (A), but are usually below 2m in North America (Ottawa, Canada) (B). Photo credit: Sheng Qiang. Figure 4. Field sampling site diagram. At each site, sampling plots were separated by at least 10 m to minimize the probability of sampling multiple ramets from individual genets. Photo credit: Guoqi Chen. Figure 5. Pollen germination and pollen tube growth on a stigma. (A) Pollen germination; (B) pollen tube growth; (C) penetration of pollen tubes into an ovary. Photo credit: Beibei Yao. These photographs illustrate the article “Solidago canadensis, a flower or weed?” by Sheng Qiang, Jiliang Cheng, Guoqi Chen, Beibei Yao published in Ecological Monographs. https://doi.org/10.1002/ecm.1445.