臺灣產樟科植物花部生物學之研究
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Date
2015
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Abstract
花的形態常與傳粉媒介共演化而呈現多樣變化，不同的花部形態會吸引不同的傳粉者而造成物種間的生殖隔離，因此在植物的繁衍上扮演著重要角色。樟科植物是構成臺灣常綠闊葉林的重要組成樹種，以往在臺灣樟科植物雖已有多位學者進行過系統分類研究，但對於花部形態的基礎研究卻仍不完整，甚至有形態描述不一致之情形。本研究針對臺灣產樟科植物選擇具代表性之類群進行花部形態及開花週期之探討，以釐清臺灣產樟科植物屬間及屬內各類群花部形態特徵與開花週期的異同，研究結果將可供授粉生物學及保育生物學等科學研究的背景。本研究觀察臺灣產之樟屬(Cinnamomum)的樟樹(Ci. camphora)、土肉桂(Ci. osmophloeum)，厚殼桂屬(Cryptocarya)的厚殼桂(Cr. chinensis)，釣樟屬(Lindera)的大葉釣樟(Lin. megaphylla)，木薑子屬(Litsea)的山胡椒(Lit. cubeba)，楨楠屬(Machilus)的大葉楠(M. japonica var. kusanoi)、紅楠(M. thunbergii)、香楠(M. zuihoensis)及雅楠屬(Phoebe)的臺灣雅楠(P. formosana)，除觀察野外個體的花部物候現象外，同時採集樣本攜回實驗室，每隔2小時觀察記錄一次開花狀態，並以相機進行縮時攝影協助記錄。
研究結果發現，單性花類群(大葉釣樟及山胡椒)之花朵開放後維持1至5日不等，並無夜間閉合之兩次開花特性；而兩性花各類群(樟樹、土肉桂、厚殼桂、大葉楠、紅楠、香楠及臺灣雅楠等)均為雌雄異熟(dichogamy)，且為雌先熟(protogynous)。大多數具晚間閉合之兩次開花特性，記錄到之開花週期共有五種類型：(A)首日上午開放而雌蕊熟，午後閉合，次日下午再度開放而雄蕊熟，晚間閉合；(B)首日下午開放而雌蕊熟，晚間閉合，次日上午再度開放而雄蕊熟，午後閉合；(C)首日上午開放而雌蕊熟，晚間閉合，次日上午再度開放而雄蕊熟，晚間閉合；(D)首日晚間開放而雌蕊熟，夜間閉合，次日上午再度開放而雄蕊熟，午後閉合；(E)不具兩次開花特性，花開時雄蕊已熟；其中類型A及B與前人研究結果相似；此外，前人研究中指出同一植株之花均屬同一類型且開放時間一致性高，但本研究觀察到部分個體同時具有兩種類型的花，單一植株不同花朵開放時間並非完全一致。
Floral morphologies are diversified because of the coevolution with pollinators. Different morphologies can attract different pollinators and lead to reproductive isolations. As a result, flowers are the most important feature of plant reproduction. Lauraceae is an important component of evergreen broad-leaved forest in Taiwan, however most studies of Lauraceae in Taiwan focus on systematics, few studies paying attention to floral biology. Therefore the description of floral morphologies and floral phenology for some taxa are incomplete or inconsistent. In this study, my aims are to identify and compare the floral morphologies and floral phenology between genera and between taxa of Lauraceae in Taiwan. The results of this study can provide basic information for pollination biology and conservation biology. We choose Cinnamomum camphora, Ci. osmophloeum, Cryptocarya chinensis, Lindera megaphylla, Litsea cubeba, Machilus japonica var. kusanoi, M. thunbergii, M. zuihoensis, and Phoebe formosana for observation. In addition to field observation of floral phenology, we cut the branches with floral buds and inserted them into water bottles in laboratory for observations. Checking the floral condition once every two hours, and recording with time-lapse photography. In my observations, unisexual flowers (Lindera megaphylla, and Litsea cubeba) maintain opening for 1 to 5 days, and these flowers neither open twice nor close in the evening. Bisexual flowers (Cinnamomum camphora, Ci. osmophloeum, Cryptocarya chinensis, Machilus japonica var. kusanoi, M. thunbergii, M. zuihoensis, and Phoebe formosana) are dichogamy and protogynous, and most of them open twice and close in the evening. The floral phenology of bisexual flowers can be categorized into the following types: (a) first day flowers open as female in the morning and close in the afternoon until next afternoon open again as male, then close again in the evening; (b) first day flowers open as female in the afternoon and close in the evening until next morning open again as male, then close again in the afternoon; (c) first day flowers open as female in the morning and close in the afternoon until next morning open again as male, then close again in the afternoon; (d) first day opening as female in the evening and close at night until next morning open again as male, then close again in the afternoon; (e) without dianthesis, flowers open as male. In addition, the flowers of the same branch we observed don’t entirely show the phenomenon of synchronous dichogamy, and some of them had two types of the floral phenology.
Floral morphologies are diversified because of the coevolution with pollinators. Different morphologies can attract different pollinators and lead to reproductive isolations. As a result, flowers are the most important feature of plant reproduction. Lauraceae is an important component of evergreen broad-leaved forest in Taiwan, however most studies of Lauraceae in Taiwan focus on systematics, few studies paying attention to floral biology. Therefore the description of floral morphologies and floral phenology for some taxa are incomplete or inconsistent. In this study, my aims are to identify and compare the floral morphologies and floral phenology between genera and between taxa of Lauraceae in Taiwan. The results of this study can provide basic information for pollination biology and conservation biology. We choose Cinnamomum camphora, Ci. osmophloeum, Cryptocarya chinensis, Lindera megaphylla, Litsea cubeba, Machilus japonica var. kusanoi, M. thunbergii, M. zuihoensis, and Phoebe formosana for observation. In addition to field observation of floral phenology, we cut the branches with floral buds and inserted them into water bottles in laboratory for observations. Checking the floral condition once every two hours, and recording with time-lapse photography. In my observations, unisexual flowers (Lindera megaphylla, and Litsea cubeba) maintain opening for 1 to 5 days, and these flowers neither open twice nor close in the evening. Bisexual flowers (Cinnamomum camphora, Ci. osmophloeum, Cryptocarya chinensis, Machilus japonica var. kusanoi, M. thunbergii, M. zuihoensis, and Phoebe formosana) are dichogamy and protogynous, and most of them open twice and close in the evening. The floral phenology of bisexual flowers can be categorized into the following types: (a) first day flowers open as female in the morning and close in the afternoon until next afternoon open again as male, then close again in the evening; (b) first day flowers open as female in the afternoon and close in the evening until next morning open again as male, then close again in the afternoon; (c) first day flowers open as female in the morning and close in the afternoon until next morning open again as male, then close again in the afternoon; (d) first day opening as female in the evening and close at night until next morning open again as male, then close again in the afternoon; (e) without dianthesis, flowers open as male. In addition, the flowers of the same branch we observed don’t entirely show the phenomenon of synchronous dichogamy, and some of them had two types of the floral phenology.
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Keywords
樟科, 花部形態, 開花週期, 雌雄異熟, 雌雄異株, Lauraceae, floral morphology, floral phenology, dichogamy, dioecy