木麻黃原為闊葉樹，後期出現了異變， 樹形，葉片，果實都像松樹．圖中像松針的小枝上可以找到輪狀的鱗片葉．

The leaves of Casuarina equisetifolia look like needle, they were originally board leave. However, its appearance, leaves and fruits became pines like species due to some uncertain reasons.  
根據香港植物誌第一冊，香港的木麻黃屬有２個品種，細枝木麻黃Casuarina cunninghamiana，和木麻黃C. equisetifolia，前者為雌雄異株dioecious，後者為雌雄同株monoecious．從樹上的花便可以分辨出這兩個品種． 圖中有果和雄花，應該是木麻黃C. equisetifolia了．

According to Flora of Hong Kong Vol. 1, there are two types of Casuarina spp.: C. cunninghamiana and C. equisetifolia in HK. The former is dioecious and the later is monoecious. The fruits and the male flowers shown in the picture clarify itself the C. equisetifolia.

圖中只有果和雌花，看不見雄花，應該是細枝木麻黃Casuarina cunninghamiana了．

木麻黃的英文俗名是"Horsetail Tree"，中文俗名是"牛尾松"，Horsetail變成牛尾，相信是香港特色文化！註：澳門也有此樹，不過中文名用的是較為合理的"馬尾松"．

Casuarina equisetifolia is called Horsetail Tree in its common name. And its Chinese common name is 『oxtail pine』"牛尾松". How can a horsetail in Chinese become an oxtail in English? Definitely it is the Hong Kong culture! P.S This tree is also found in Macau, but its Chinese name is "馬尾松"『Horsetail Tree』, which is more reasonable.

*translated by Paula Wong