Two new national second-class protected wild plants discovered in Guangdong: Ormosia yangjiangensis and Ormosia taishanensis

"Red berries grow in southern land, how many spring branches hold?" The red beans described by WANG Wei in his poem have carried the longing of Chinese people for thousands of years. Today, right in the "southern land" mentioned in the poem—the Guangdong-Hong Kong-Macao Greater Bay Area—a research team has unveiled the mystery of two new species of the genus Ormosia. Once confirmed, these two new species were automatically included in the national protection list, becoming two new additions to Guangdong's national second-class protected wild plants.

Recently, a team led by researcher CHEN Yousheng from the South China Botanical Garden, Chinese Academy of Sciences, published a paper in the international journal Phytotaxa, formally describing and naming Ormosia yangjiangensis and Ormosia taishanensis. The type localities of both species are located in the Pearl River Delta and adjacent areas, within the scope of the Guangdong-Hong Kong-Macao Greater Bay Area. According to the 2021 edition of the National Key Protected Wild Plants List, all species of the genus Ormosia are already under protection, meaning that once these two new species were published, they automatically received national second-class protection status.

Why were they "misidentified" for decades?

This discovery originated from the compilation work of the Guangdong Plant Red Book. During field surveys, researchers repeatedly found plants morphologically similar to Ormosia indurate and Ormosia xylocarpa, but their flower and fruit characteristics never matched any known species.

The key issue lies in the long flowering and fruiting cycle of the genus Ormosia, making it difficult for researchers to collect complete specimens with both flowers and fruits. Previous taxonomic studies mainly relied on leaves and dry pods, which is precisely the most prone to misjudgment: leaf morphology varies significantly in the same species under different environments, while leaves of different species can be highly similar; dry pods also lose many key morphological features.

To clarify the truth, the team spent several years repeatedly visiting Yangjiang, Taishan, and other locations for follow-up investigations, ultimately successfully collecting complete specimens from flowering to fruiting stages. Combining morphological comparisons with DNA molecular phylogenetic analysis, the team confirmed that these plants, long misidentified, were actually two previously undescribed new species.

Ormosia yangjiangensis: Large flowers, flat pods, fewer than 500 mature individuals

Ormosia yangjiangensisis an evergreen small tree, mainly distributed in Yangxi County, Yangjiang City, with sporadic populations also found in Enping City, Jiangmen. Its flowers reach up to 2.5 cm in length, about the size of a coin, making them relatively large among the genus Ormosia; its pods are flat like miniature knife sheaths, differing from the common rounded pods. Compared to its relatives Ormosia xylocarpa and Ormosia pubescens, O. yangjiangensis has thinner leaflets, inflorescences that are lateral or terminal, and pod ventral sutures without ridges.

However, only three wild populations of this species exist, with fewer than 500 mature individuals. Growing mostly at low altitudes along riverbanks, their roots are easily destroyed by floodwaters during the rainy season, and coupled with human logging, natural population regeneration is limited. According to IUCN criteria, Ormosia yangjiangensis is assessed as Endangered (EN).

Ormosia taishanensis: Pods thick as coins, fewer than 100 remaining

If Ormosia yangjiangensis represents the "flat type," then Ormosia taishanensis is the "thick type." Its pod valves reach 6 to 11 mm in thickness, equivalent to stacking several coins; the ventral suture has obvious ridges, and the seed hilum is 3 to 4 mm long. These details are key clues for distinguishing species.

The situation for Ormosia taishanensis is even more critical: only three wild populations have been discovered, with fewer than 100 mature individuals. It has been assessed as Critically Endangered (CR) and recommended for inclusion in the list of plant species with extremely small populations, facing the risk of extinction in the wild.

Flowers and fresh pods: More reliable identification evidence

This study brings important scientific insights: for leguminous plants, the morphological characteristics of flowers and fresh pods are more reliable than those of leaves and dry pods. For a long time, researchers relied on leaf morphology because leaves were easier to obtain, but the flowering period of the genus Ormosiais brief, and most specimens lack floral records. This study demonstrates that floral morphology is a key "fingerprint"—the flower buds of Ormosia yangjiangensis are pointed like tops, with mixed brown and white hairs inside the calyx lobes; the flower buds of Ormosia taishanensis are ovoid or top-shaped. These features are difficult to observe in dried specimens and can only be captured through live observation.

Similarly, characteristics such as the thickness of fresh pods and ridges on the ventral suture are lost after drying, yet these are precisely important clues for distinguishing the two new species. "Relying solely on a limited number of specimens for species identification can easily lead to misclassification." This sentence from the paper serves as the perfect footnote for the entire study.

Conservation action: Seamless transition from "new species" to "national protection"

Once published, the two new species were automatically included in national second-class protection. Currently, they have been ex-situ conserved at the South China Botanical Garden, and the team has established the world's most species-rich germplasm resource nursery for the genus Ormosia. The research team calls for immediate implementation of in-situ habitat conservation, establishment of population dynamics monitoring mechanisms, and focused attention on natural regeneration—without seedlings growing into saplings, even numerous adult trees represent nothing more than a "last supper."

The paper also updates the dichotomous key for identifying Ormosia species in Guangdong Province, providing a standardized tool for field identification. The discovery of these two new species confirms a fact: even in densely populated areas like the Guangdong-Hong Kong-Macao Greater Bay Area, unknown life forms still await discovery. Every Ormosia tree is a unique gene bank, and every new species is a window to an unknown world. Protecting them means protecting our shared home.

Figure.1. Phylogenetic tree obtained via the concatenation approach based on 2,185 loci from IQ-TREE.（Image by CHEN Yousheng）

Figure.2. Ormosia yangjiangensis.（Image by CHEN Yousheng）

Figure.3. Ormosia taishanensis.（Image by CHEN Yousheng）