臺灣產山黑扁豆屬雜交種之形態學證據

Morphological Evidences for Hybrid of Dumasia (Fabaceae) in Taiwan

本文利用形態學的證據來研究疑似苗栗野豇豆和臺灣山黑扁豆之間的雜交種。苗栗野豇豆葉基截形、葉光滑或具毛；花柱及子房柄長且光滑無毛；果莢鐮刀狀、果皮平滑無毛、成熟時黑色；種子呈黃褐色。臺灣山黑扁豆葉基銳尖、具柔毛；花柱及子房柄短且具毛；果莢圓柱狀、果皮披棕色柔毛、成熟時綠色；種子呈深藍色。但在二本松發現兩種間有一疑似雜交種，此疑似雜交種和苗栗野豇豆外部形態類似，但其莢果圓柱狀、子房柄短則和臺灣山黑扁豆相似。苗栗野豇豆的平均花粉可孕性染色比率為92.5%，臺灣山黑扁豆的平均花粉可孕性染色比率為87.4%，疑似雜交種的平均花粉可孕性染色比率只有55.3%。染色體數均為2n=20。苗栗野豇豆目前分佈只侷現於新竹清泉及苗栗二本松海拔介於1100-1500公尺處，臺灣山黑扁豆分佈於全省500-2500公尺之山地，疑似雜交種發現和苗栗野豇豆與臺灣山黑扁豆混生於一起。

Plants intermediate in appearance between Dumasia miaoliensis and D. villosa subsp. bicolor are assumed to be the result of hybridization. Dumasia miaoliensis has the leaf base truncate, leaves glabrous or pubescent, style and gynophore long and glabrous, pods falcate, black and glabrous and seeds yellowish brown. Dumasia villosa subsp. bicolor has the leaf base acute, leaves soft hairy, style and gynophore short and villosa, pods terete, yellowish brown and villose and seeds blue. The putative hybrid is more similar to D. miaoliensis, but has terete pods and short gynophore similar to D. villosa subsp. bicolor. Pollen stainability for D. miaoliensis, the putative hybrid and D. villosa subsp. bicolor is 92.5%, 55.3% and 87.4%, respectively. Dumasia villosa subsp. bicolor occurs in the mountains at 500-2500 m. Dumasia miaoliensis occurs only at Chingchieng and Erpenshong between 1100 and 1500 m. The putative hybrid was found intermixed with or growing near the D. villosa subsp. bicolor and D. miaoliensis.