臺北自來水園區環境教育中心

九芎分布於臺灣全島平地及山麓、中國大陸、琉球等地。樹皮為紅褐色，剝落後呈灰白色，樹幹光滑堅硬。由於九芎的樹皮非常光滑且成片剝落，聽說連猴子爬上去都會滑下來，因此也稱為「猴溜」或「猴不爬」。九芎的木材質地緻密而堅韌，早期臺灣民間就已知取其通直的樹幹來做為房柱，且要以火將要埋入土中的木材基部烤焦，並形成一層薄炭包覆木材，讓白蟻或蛀蟲無法入侵。
The Subcostate Crape Myrtle (Jiuqiong) is seen everywhere in Taiwan, mainland China, and the Ryukyu Islands. The trees are red-brown outside and grey-white inside, with slippery and hard tree trunks. Since the bark is slippery and comes off in big flakes, it is said that even monkeys cannot successfully climb up the trees, and that's why they are also called "Monkeys Slip" (Houliu) or "Monkeys Don't Climb" (Houbupa). The Taiwanese knew in the early days that the tree's wood could be used to make pillars because of its strong quality and dense texture. They charcoaled the end of the wood extending into the ground with fire to make it termite- or borer-proof.