Walking down into one of the valleys below Thumb Hill, in an especially damp and shady spot where several streams flow, the Java fern (Microsorium pteropus), a favorite aquarium plant, grows in the babbling water.
下到拇指山凹谷，幾條小山澗間異常陰濕，山凹汩汩的流水中有喜愛泡水的「三叉葉星蕨」，是水族業者口中的「鐵雞冠」，常被養在水族箱裡。