台灣產呂宋莢蒾（五福花科）之葉片物候與兩型性之研究

Abstract

木本非單子葉被子植物的葉緣與氣候分佈之間有強烈的關聯性。分佈在溫帶中濕型森林的物種通常具有鋸齒緣的葉片，分佈在熱帶中濕性森林的物種則具有全緣葉片。葉片發育時受到休眠芽的空間限制而折疊可能導致葉緣鋸齒的形成。一些木本植物，例如呂宋莢蒾（Viburnum luzonicum），同時具有在休眠芽內發先育好的preformed leaves與直接在枝條上發育的neoformed leaves，可用以研究葉形與葉片是否經歷休眠芽時期之間的關係。 本研究調查了陽明山巴拉卡公路（海拔840 m）、台北北投丹鳳山（海拔120 m）與台北植物園（海拔低於50 m）的落葉性灌木呂宋莢蒾的葉片物候，並記錄標記枝條上的葉片壽命及葉形。呂宋莢蒾在一個生長季內會有一至二次葉片萌發。第一次葉片萌發約在2月至4月，所有葉片皆為於前一生長季形成在休眠芽（過冬芽）內發育好的preformed leaves；第二次萌發在3月至4月的花期之後，通常會具有一對於當季在芽苞內發育好preformed leaves與一至數對neoformed leaves。有80.85%標記於丹鳳山與台北植物園的枝條有第二次的葉片萌發，而陽明山巴拉卡公路僅有31.58%具有第二次的葉片萌發。第二次萌發的葉片具有較少的葉緣鋸齒數（為第一次萌發葉片平均值的42.67%）、較淺的鋸齒與較小的葉片面積（為第一次萌發葉片平均值的32.29%）。本研究得出以下結論：有經歷過冬芽的葉片會比未經歷過冬芽的葉片具有更深的鋸齒緣，分佈在年均氣溫較低之環境、在過冬芽內經歷較長時間的葉片也會有更深的鋸齒緣。

Leaf margins of woody non-monocot angiosperms strongly correlate with their climatic distribution. Species in temperate mesic forests usually have leaves with toothed margins while species in tropical mesic forests have leaves with entire margins. The formation of leaf teeth may be caused by the space limitation of resting buds and leaf folding in buds during leaf development. Viburnum luzonicum like several other woody plants, has the preformed leaves developed in resting buds and neoformed leaves developed directly along shoots, therefore can be used to study the relationship between leaf shape and the appearance of resting buds when leaves developed. Leafing phenology of deciduous shrub V. luzonicum in Balaka Road in Yangmingshan National Park (YMSNP, elevation 840 m), Mount Danfeng in Taipei City (elevation 120 m) and Taipei Botanical Garden (TPBG, elevation under 50 m) was studied here, and recorded for the life-span and shape of each leaves on the study branches. V. luzonicum exhibited one or two leaf flush in a growing season. The first flush is from February to April. All of the leaves in this flush are preformed leaves, which developed in resting buds of last growing season (winter buds). The second flush is after the flowering in March and April, and usually with a pair of preformed leaves (developed in resting buds in this growing season) and one to several pairs of neoformed leaves. In Mt. Danfeng and TPBG, 80.85% of tagged branches have second leaf flush, while 31.58% in YMSNP can have a second leaf flush. Leaves in second flush have less (42.67% of means teeth number of first flushing leaves) and shallower teeth, and a smaller leaf area (32.29% of means area of first flushing leaves). This study concluded that leaves developed in winter buds will have more toothed margin. Furthermore, leaves that have longer period in winter buds will also have more toothed margin.