Alien woody plants are more versatile than native, but both share similar therapeutic redundancy in South Africa

Abstract

Understanding why alien plant species are incorporated into the medicinal flora in several local communities is central to invasion biology and ethnobiology. Theories suggest that alien plants are incorporated in local pharmacopoeias because they are more versatile or contribute unique secondary chemistry which make them less therapeutically redundant, or simply because they are locally more abundant than native species. However, a lack of a comprehensive test of these hypotheses limits our understanding of the dynamics of plants knowledge, use and potential implications for invasion. Here, we tested the predictions of several of these hypotheses using a unique dataset on the woody medicinal flora of southern Africa. We found that the size of a plant family predicts the number of medicinal plants in that family, a support for the non-random hypothesis of medicinal plant selection. However, we found no support for the diversification hypothesis: i) both alien and native plants were used in the treatment of similar diseases; ii) significantly more native species than alien contribute to disease treatments particularly of parasitic infections and obstetric-gynecological diseases, and iii) alien and native species share similar therapeutic redundancy. However, we found support for the versatility hypothesis, i.e., alien plants were more versatile than natives. These findings imply that, although alien plant species are not therapeutically unique, they do provide more uses than native plants (versatility), thus suggesting that they may not have been introduced primarily for therapeutic reasons. We call for similar studies to be carried out on alien herbaceous plants for a broader understanding of the integration of alien plants into the pharmacopoeias of the receiving communities.

Impact of Invasive Plant Species on Ecosystems, Biodiversity Loss and Their Potential Industrial Applications

“…Rai and Singh (2020) highlighted the consequence of increasing the level of air pollutants, as alien species are not as efficient in their absorption: this can cause lung and cardiovascular problems. As a contradiction, in terms of medicinal properties, foreign species can be used for more purposes than native species (Yessoufou et al, 2021), but it is necessary to be taken into account their toxicological potential. Ailanthus altissima bark, for exemple caused hepatic and gastrointestinal dysfunction in certain high amounts, and even the death of involved mice (Liu et al, 2019), while Gutenbergia cordifolia affected the metabolism and the microbial community of the rumen (Ngondya et al, 2019).…”

The Patterns of Intraspecific Variations in Mass of Nectar Sugar along a Phylogeny Distinguish Native from Non-Native Plants in Urban Greenspaces in Southern England

“…Species are moved across the globe accidentally or intentionally by humans [ 1 ] for specific ecosystem services these species provide, e.g., horticultural, medicinal, or ecological services [ 2 , 3 ]. However, although introducing non-native species into new environments provides some benefits (e.g., erosion control, medicinal uses, etc.…”

“…However, the second question still deserves attention. A recent study demonstrated that non-native plants of economic values (e.g., animal food and ornamental) are almost 20 times more likely to naturalize than not, and the naturalization likelihood increases for non-native plants that provide higher number of uses ([ 3 ]; see also [ 2 ]), thus showing the importance of human selection criteria of non-native plants in contributing to their naturalization. I define human selection criteria as the reasons (e.g., erosion control, medicinal uses, food, horticultural values, etc.)…”

“…[ 3 ] showed a phylogenetic pattern in the naturalized flora, thus implying that human selection criteria of non-native plants have a phylogenetic component. These studies [ 2 , 3 ] provide evidence that the understanding of obvious (e.g., horticultural and medicinal) or hidden criteria (e.g., phylogeny) subtending human selection of non-native species is key for predicting their outcomes (e.g., naturalization) or the mechanisms that provide an upper hand to non-native species in the competition for ecological dominance.…”

A Comprehensive Review of Croton joufra

“…Croton joufra Roxb belongs to the Euphorbiaceae family, which is found in India, Bhutan, Vietnam, Bangladesh, and Myanmar at altitudes below 1000 m. Various parts of the plant are extensively used medicinally in regional pharmacopoeias 17 . As a medicinal plant, it has been used for the treatment of various diseases like helminthic infections.…”