Vegetation on the Penghu Island Group can be divided up into seven categories according to use: shade trees, roadside trees, windbreak trees, firewood trees, riverbank trees, multi-purpose trees and fruit varieties. There are many different kinds of shade trees. The wide open environment of Penghu is just right place for banyan tree which is native to the tropics. Banyan trees are suitable for planting around the Ma-gong Castle, nearby the barracks’ gate, on ridges between fields and empty spaces, etc. Additionally, other trees native to the tropics such as Ficus wightiana (red fruit fig tree), Cockspur coral-tree, Terminalia catappa (Indian almond), and Tamarind trees are also perfect shade trees. Roadside trees are related to human health. When choosing which trees would be planted, considerations had to be paid to the shape of trees and its shade effect. Ptychosperma elegans, Eucalyptus, Robinia pseudoacacia, and Garcinia subelliptica are good choice for shade trees. As the wind is very strong in Peng-hu, trees recommended for windbreaks for the place include Garcinia subelliptica, Calophylium inophyllum (Indiapoon Beautyleaf), and Pinus luchuensis Maryr. Four kinds of trees are considered useful firewood trees: Robinia pseudoacacia, Pongamia pinnata, Melia azedarach (China tree/ China berry), and Hernandia nymphiifolia. Riverside trees include Weeping Willows from the Salicaceae family which we can often find in warm and moist areas, and Eucalyptus from Australia. Multi-purpose trees are to be chosen through economic considerations for their use in construction, windbreaks, fruit-growing, shading, etc. Among many different kinds of trees deemed to be Multi-purpose trees, seven have been selected to popularize: coconut trees, Areca catechu Linn (betel nut trees), Livistona chinensis (Chinese fan palms), Arenga pinnata (Sugar palms), Pandanus tectorius (Screw pines), Hibiscus tiliaceus, and the Rhizophoraceae family. Fruit plants are mostly tropical varieties such as pineapple, banana, lemon, Citrus sinensis, Citrus grandis (Citrus maximum), other citrus varieties, papaya, Ficus carica Linn (fig), mango, breadfruit, etc.