The Diversity of Pistillate Flowers and Its Taxonomic Value to the Classification of Daphniphyllum (Daphniphyllaceae)

虎皮楠科植物雌花的多樣性其及分類價值

唐默詩(Mo-Shih Tang) ； 楊遠波(Yuen-Po Yang) ； 蔡奇助(Chi-Chu Tsai) ； 許秋容(Chiou-Rong Sheue)

《Botanical Studies》 53卷4期 (2012/10) Pp. 509-524

摘要

虎皮楠科植物僅具虎皮楠一屬，雌雄異株；花單性，不顯著，結構退化且往往早落。其葉、雄花和果實可資應用的分類特徵十分有限；與前者相較，雌花的特徵較多且穩定，對其分類極有幫助。然而雌花的相關報導卻仍相當稀少，諸此原因，造成本屬物種鑑定之困難和屬下分類位階－節或系等的不確定性。本研究觀察19個分類群，報導虎皮楠屬雌花的多樣性和其發育之主要變化，除了提供本科植物分類特徵之參考外，也有助於屬下的分類評估。虎皮楠的雌花柱頭可分成四型：點狀、腎形、線形和長橢圓形。除了點狀柱頭外，其他三型的柱頭在開花的過程中都會有延長的現象。在研究的19個分類群中，三個分類群的雌花無花萼，其他分類群的花萼可區分成三型：萼片離生，合生深裂和合生淺裂。不孕性雄蕊的存在和宿存與否亦為鑑別特徵。本研究結果支持本屬的屬下分類系統依黃氏原先之處理，分為三個節：虎皮楠節、半月形藥節和不妊性雄蕊節，並建議將原屬於虎皮楠節其中的二物種歸屬為不妊性雄蕊節。

關鍵字

早落的 ； 花萼 ； 虎皮楠節 ； 半月形藥節 ； 不孕性雄蕊 ； 不妊性雄蕊節 ； 柱頭 ； 分類價值

並列摘要

Daphniphyllum is the sole genus of the family Daphniphyllaceae consisting of dioecious species with inconspicuous reduced unisexual mostly caducous flowers. The paucity of helpful taxonomic characters from vegetative and reduced reproductive organs has led to difficulties in intrageneric classification and species identification. The pistillate flowers have characters of higher taxonomic value than those of the vegetative organs, staminate flowers and fruits, but pistillate flower information is rarely reported. Here pistillate flowers of 19 taxa were studied to reveal pistillate floral diversity and major developmental features with a view to intrageneric classification. Four types of stigma shape were recognized: punctiform, reniform, linear and oblong. Daphniphyllum stigmas, except for the punctiform type, elongate variously after an early stage of anthesis. The pistillate flowers of three taxa are asepalus. The calyces of other taxa were categorized into three types, free, cleft and parted, which are consistent within taxa. The existence and persistence of staminodes are diagnostic characters. This study shows that the characteristics of pistillate flowers provide helpful information for identification at the species and even the variety level. Our results do not support the currently accepted two sections, Daphniphyllum and Lunata. Instead, Huang's original intrageneric classification into three sections, Daphniphyllum, Lunata and Staminodia, is supported, but with two species previously in Daphniphyllum reassigned to Staminodia.

並列關鍵字

Caducous ； Calyx ； Daphniphyllum ； Lunata ； Staminode ； Staminodia ； Stigma ； Taxonomic value