二球懸鈴木(英國梧桐) ．Platanus x acerifolia在香港也有種植，它的x顯示它是雜交品種，由一球懸鈴木(美國梧桐P. occidentalis)和三球懸鈴木(法國梧桐 P. orientalis)而來的．未知一球懸鈴木和三球懸鈴木是否適合香港環境，否則三棵樹木並排而種，結果時以樹上果實的一球，兩球和三球來辨認，甚有特色．

The system of naming plants is binomial nomenclature.  The botanical names of each species are usually formed by the combination of two words, which are in a modern form of Latin.  The first word is the genus name and the second word identifying the species within that genus. There is an exception where there is an 「x」 in between the two names.  According to 「Flora of Hong Kong」, the trees in Hong Kong which get an 「x」 are:

． Common Banana (Musa x paradisiaca)
． White Champak (Michelia x alba)
． London Plane (Platanus x acerifolia)

Common Banana is a variety which has been repeatedly improved.  It becomes easier to cultivate and the small seeds become more delicious. 

White Champak is the hybridization of two from the same genus.  Fruit is rare. It is usually propagated by air-layering.  I think as fruiting White Champak is not common, for educational purpose, it should be clearly and correctly identified. 

London plane has also been grown in Hong Kong.  Its 「x」 indicates that it is a hybrid of American Sycamore (Platanus occidentalis) and Oriental plane (Platanus orientalis).  We don』t know if American Sycamore and Oriental plane can survive in Hong Kong.  Otherwise, it would be quite interesting to see these three kinds of trees standing side by side.  Then, when it』s the fruiting season, we can identify the trees by counting the quantity of fruit in a cluster. This is quite distinctive, isn』t it?