Comparing and Contrasting Polygonum lapathifolium and Eriogonum grande var. rubescens, Two Members of the Polygonaceae Family
These two species fall under the Polygonaceae, which are a family of flowering plants known informally as the knotweed or smartweed-buckwheat family in the United States. While the two plant species belong to separate genera, their shared inclusion under the same family is a meaningful commonality, as it informs the observer of their relatedness and their classification processes. Interestingly, in the last comprehensive revision of the plant family published in 1993, the family was divided into two subfamilies, namely Eriogonoideae and Polygonoideae, on the basis of earlier systems of plant classification (Brandbyge, 1993). While the circumscriptions of these two subfamilies have since been changed in light of phylogenetic studies of DNA sequences, the Eriogonum and Polygonum genuses have maintained their position on the Polygonaceae phylogenetic tree. Such a tree shows a considerable evolutionary distance between them, which seems to correspond with their observed differences.
These differences begin with their collection processes. In terms of herbariums, the collection process is rather methodical, since it gives value to the specimen. This process usually involves recording what was collected, where it was collected, when it was collected, and who collected it. This information is made readily available on herbarium specimen sheets, usually in the form of an attached label. Looking at the P. lapathifolium specimen, for example, an observer learns that this sample was collected by O. H. Kappler around the South Fork of the Yuba River in 1946. Although this process has become standardized with the establishment of herbariums, the core elements of this practice have been observed for some time. This is clear when analyzing the Materia Medica entry of P. lapathifolium, which illustrates the collected plant and lists its collectors, collection location, and collection date. While this information is valuable in itself, it also provides context to the specimen and allows an observer to make meaningful comparisons between them. For example, one could consider how the differences in flower structure between these two entries might relate to the unique habitat characteristics associated with their collection locations, as P. lapathifolium is considered native to both Europe and North America.
Contrastingly, specimens in a botanical garden are documented collections of living plants for research, conservation, display, and education. It seems reasonable to assume that Eriogonum grande var. rubescens, which is native and endemic to California, was grown in the botanical garden or otherwise obtained from another location in the state. While specific collection information is not disclosed, inferences can be made as above on the basis of its habitat, for example. Although there seem to be considerable differences between the structures and habitats of Eriogonum grande var. rubescens and P. lapathifolium, this could plausibly reflect their growth needs and how they are met by different environments (California and Europe/Asia, respectively).
These differences are also observed in terms of these species’ medicinal potential. There are many publications, both historical and modern, detailing the healing properties of P. lapathifolium; the entire plant itself has been claimed as an antiseptic and astringent, while specific extracts of the plant have been shown to have antioxidant or anti-inflammatory activity. However, there seems to be a lack of information in the literature regarding such properties of Eriogonum grande var. rubescens.
Works Cited
Brandbyge, J. 1993. "Polygonaceae". pages 531-544. In: Klaus Kubitzki (editor); Jens G. Rohwer, and Volker Bittrich (volume editors). The Families and Genera of Vascular Plants volume II. Springer-Verlag: Berlin; Heidelberg, Germany ISBN 978-3-540-55509-4 (Berlin) ISBN 978-0-387-55509-6 (New York)