What tree has no skin on top and skin on the bottom?

This is Lagerstroemia speciosa, alias: itch flower, prurigo, purple flower, purple orchid, mosquito flower, Myrica rubra, zinnia, skinless tree, deciduous shrub or small tree of Lagerstroemia, 7 meters high; Bark is smooth, gray or grayish brown; Twisted branches, slender branchlets, alternate or sometimes opposite leaves, papery, oval, oblong or obovate, green to yellow when young, purple-black when mature or dry, and ventricular dehiscence; Seeds winged, ca. The flowering period is from June to September, and the fruiting period is from September to June. Lagerstroemia indica has beautiful posture, smooth trunk and bright colors; When it blooms, it happens to be the season when there are few flowers in summer and autumn, and the flowering period is long. Therefore, it is known as "Hundred Days Red" and "Summer Blue and White Flowers Full", and it is a good bonsai for viewing flowers, stems and roots; Roots, bark, leaves and flowers can be used as medicine. Eucalyptus citriodora (Latin scientific name: Eucalyptus citriodora. F) is an evergreen tree, with a height of 40m and a DBH1.2m. Its trunk is tall and straight, and its bark is smooth and white, so it is known as the "fairy in the forest". Originally from Australia, it has been introduced to China for nearly a hundred years. It is cultivated in China, South China, Fujian, Zhejiang, Yunnan and Sichuan. Being fond of light, adaptable to climate and soil, drought-tolerant, fast-growing and high in wood yield, it is an important afforestation tree species in southern China. It is suitable for afforestation in the lower part of southern hilly and coastal mountainous areas and surrounding greening. At the same time, it is also an important fast-growing timber tree species and excellent aromatic oil tree species in southern China. Rich in aromatic substances.