Scientific Name : Peltophorum tonkinense (Pierre) Gagnep.
Common Name : Yinzhu
Chinese Name : 銀珠, 油楠
Family : CAESALPINIACEAE
Local distribution status : Exotic species
| Origins | Hainan Province. This species is also distributed throughout Northern Vietnam. |
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| Ecology | The natural habitat of the species consists of sparse forests and mountain slopes. In China's Higher Plants Red List, it is rated as an endangered species. |
| Meanings of name | Yinzhu has oblong leaflets, which have a shiny and deep green upper surface that glitters like gemstones under sunlight. Hence, the plant is called "Silver Beads (銀珠)" in Chinese. |
| Yinzhu and Yellow Poinciana | Both species belong to the genus Peltophorum of the family Caesalpiniaceae. They share similar appearances, both possessing bipinnately compound leaves and bright yellow flowers. They are both cultivated as street trees. However, it is not difficult to distinguish between the two. Firstly, we can look at the leaves. The upper surface of mature leaflets of the Yinzhu is glossy, but those of the Yellow Poinciana (Peltophorum pterocarpum (DC.) Baker ex K. Heyne) are comparatively dull. Comparing the trunks, the bark on the main trunk of Yinzhu is smoother than that of the Yellow Poinciana, with horizontal stripes. Their flowering seasons are also different. The flowering period of Yinzhu is earlier, from March to June, while the Yellow Poinciana blossoms later, from June to August. Flowers of Yinzhu arrange in a raceme, whereas those of Yellow Poinciana are arranged as compound raceme, i.e. panicle. Both of their fruit are fusiform legumes, but the fruits of the Yinzhu asymmetrically acuminate at both ends, smooth and not striate. In contrast, the fruits of the Yellow Poinciana conspicuously striate on surface. |
| Growing habit | Deciduous tree. |
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| Height | To 20 m. |
| Stems | Bark of trunk greyish brown. Young branches and inflorescences densely ferruginous hairy, glabrescent. Old branches densely with small ferruginous lenticels. |
| Leaves | Even-bipinnate, both pinnae and leaflets opposite. Pinnae 6 to 13 pairs, with 5 to 14 pairs of oblong leaflets each. Adaxially dark green, leathery and glossy when old, pale green abaxially. |
| Flowers | Yellowish, large and fragrant. Petals 5, obovate-orbicular, margin undulate, ferruginous villous on midvein on both surfaces. Calyx 5-lobed, lobes ovate. Pedicels ferruginous hairy. |
| Fruits | Legume fusiform, thinly leathery, winged on both sides, both ends acuminate asymmetrically. Hairy at first, reddish brown when mature, smooth and glabrous, not striate. With 3 to 4 seeds. |
| Seeds | Obliquely obovoid, compressed, yellowish when mature. |
| Flowering period | March to June in Hong Kong. |
| Fruiting period | July to October in Hong Kong. |
Scientific name above is based on Hong Kong Herbarium website : https://www.herbarium.gov.hk/en/hk-plant-database/plant-detail/index.html?pType=species&oID=9980
Scientific names from other databases
― Flora of China : Peltophorum tonkinense (Pierre) Gagnepain
― Plants of the World Online : Peltophorum dasyrhachis var. tonkinensis (Pierre) K.Larsen & S. S. Larsen