嫁接大法:洋紫荊

Ten Woods, Ten Stories

- Magic of Grafting:  Bauhinia x blakeana

香港市花洋紫荊是一種只長花不結果的無籽品種，繁殖以無性繁殖法的扦插法和嫁接法上來進行．扦插法以枝條種植，生長緩慢，亦會出現樹形彎曲的後遺症．嫁接繁殖法一般為果農喜用的繁殖方法，將想要的樹木的枝條插在同屬樹木的樹幹上，免除了樹幹的漫長成長期．

嫁接種植的洋紫荊會出現兩截，上半部是洋紫荊，下半部是紅花羊蹄甲．只要仔細留意樹幹中間有接駁痕跡，樹幹的上方和下方的樹皮紋理有顯著的不同，而樹上的葉片和樹腳的葉片也有細小的差異．當我們見到以嫁接法種植的樹木時，樹名是洋紫荊只是它其中一個答案，它另一個答案是紅花羊蹄甲．（當此樹的樹腳長葉開花時更應該冠以２個樹名．）

谷主有個想法，洋紫荊既然是百多年前由紅花羊蹄甲和宮粉羊蹄甲雜交而來，找一棵有三支分枝的紅花羊蹄甲，分別把洋紫荊和宮粉羊蹄甲嫁接上去，便可以顯示一個月份中它們三棵樹木的花期和果期的分別了．

三月，此樹便會開出洋紫荊和宮粉羊蹄甲的花，和紅花羊蹄甲的果了．

Hong Kong Orchid Tree, Bauhinia x blakeana, is a seedless species which only flowers but not fruits.   It propagates asexually by either 『cuttings』 or 『grafting』.  『Cuttings』 is to bury a piece of stem in the soil, including at least one leaf node. The cutting is then able to produce new roots, usually at the node.  This method is slow and may result in bending trunks. 『Grafting』 is usually adopted by orchard farmers.  The shoot of a selected, desired tree is grafted onto the rootstock of another species in the same genus. It can reduce the time to flowering and shorten the hybrid breeding program.

The 『grafted』 Bauhinia appear in two segments:  the upper half is Bauhinia x blakeana and the lower half is Bauhinia purpurea.  When you look at the joint carefully, then you will notice that the bark textures on both halves are significantly different.  Also, the leaves on the branches and those near the foot vary a little bit.  When we see the 『grafted』 Bauhinia, Bauhinia x blakeana is just one of the tree names.  Bauhinia purpurea is another one.  (Well, if the foot of this tree does have leaves and flowers, then it should be labeled with two names.)

I have a notion.  Inasmuch as Bauhinia x blakeana is the hybrid of Bauhinia variegata and Bauhinia purpurea more than a century ago, if in a Bauhinia purpurea tree with three shoots, we graft on with Bauhinia x blakeana and Bauhinia variegata respectively; then, the differences of the three species can be shown in the month of flowering/fruiting.

In March, this tree will be with flowers of Bauhinia x blakeana and Bauhinia variegata, plus fruit of Bauhinia purpurea.

*translated by Mary Chung

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