Precious Polygonaceae: Insight into the Historical Collection and Therapeutic Uses of Polygonum, Eriogonum, and Rumex Genera
While Materia Medica highlights the utility of plants and how humans can rely on nature, it is also important to consider the processes that led to these plants being documented in this manner. The value of these entries in part lies in their collection processes, especially in the sense of knowing their collection details. Such information often includes the collector, collection location, and collection date, alongside detailing the collected specimen itself. As evidenced by Materia Medica, there was clear importance to this information that has stood the test of time. This is especially true in terms of herbaria, or collections of preserved plants. There are about 3,100 herbaria worldwide, with 390 million specimens contained in them. Though impressive, these specimens only hold value if they detail what was collected, where it was collected, when it was collected, and who collected it. This process has become pretty standardized in herbaria, as exemplified on the physical specimen sheet of Eriogonum umbellatum var. umbellatum. All specimens in the UCLA Herbarium contain a similar label, which lists the aforementioned collection details. There may even be additional information, such as the elevation or location coordinates. Having this information gives these specimens ecological and evolutionary value, which can certainly complement their medicinal value. In this way, it allows viewers to make comparisons, whether in terms of the collected information itself or the broader context of the plant.
As such, an integration of information derived from various sources of Materia Medica, preserved herbarium specimen sheets, and living botanical garden specimens gives way toward attaining a more holistic understanding of the plant family Polygonaceae. Each page within this section analyzes three specimens: one from the UCLA Herbarium, one from the Mildred E. Mathias Botanical Garden, and one from a relevant piece of Materia Medica. In order, these pages considered Polygonum lapathifolium and Eriogonum grande var. rubescens; Eriogonum umbellatum var. umbellatum torr. and Eriogonum giganteum var. compactum; and Rumex acetosella and Eriogonum cinereum. While all of these specimens fall under the Polygonaceae family, there are clear differences in their form - dried, alive, and illustrated, respectively - and often more nuanced differences in their representation. The analyses generally compare the collection information and morphological details of the plants and go on to situate these comparisons in a historical context. Specifically, it was of interest to consider why such differences may exist. For example, between the P. lapathifolium herbarium specimen and Materia Medica entry, there were differences in flower structure. Using the collection information, one can consider how this discrepancy may relate to their nativity, for example.
Comparisons like these can also be drawn between this whole collection of plants. As mentioned previously, all of the plants in this section fall under the same family - Polygonaceae - giving them a meaningful commonality that can serve as a basis for their comparison. Interestingly, in the last comprehensive revision of this 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, Polygonum, and Rumex genera have maintained their position on the Polygonaceae phylogenetic tree. Such a tree shows each of these genera to branch from a separate node, indicating their evolutionary distance from each other.
This evolutionary distance is reflected in their morphology: looking between the three originally assigned plants, one can quickly point to many differences between them. Just one example of this is in the leaves, which vary in shape, size, and distribution. The leaves of P. lapathifolium are large and tear-drop-shaped with several visible veins; those of Eriogonum umbellatum var. umbellatum are small and rounded, with inconspicuous veins; and those of R. acetosella are small, skinny, and long. This variation is also observed in terms of their medicinal potential. For example, the E. umbellatum plant has historically been utilized by Native American tribes to treat sores, pains, and upset stomachs, among other ailments; R. acetosella is known for its treatment of inflammation and pain; and P. lapathifolium as a whole has been employed in an antiseptic fashion, with specific portions of the plant associated with antioxidant or anti-inflammatory activity. Just as before, one can consider the collection processes or collection details of these plants and how they may be responsible for their differences, which are largely expected, since the plants each fall under a different genus.
From synthesizing this information and analyzing the plants in this way, one can appreciate the significant diversity that exists within a single plant family. Even more significant, this diversity extends beyond first glance, to these plants’ collection processes and utility in society. To have this realization is to see the immense value in these practices that has been known for centuries.