Stipules and Colleters of the Mangrove Rhizophoraceae: Morphology, Structure and Comparative Significance

紅樹科紅樹林植物的托葉與指狀腺體的形態與構造之比較研究

許秋容(Chiou-Rong Sheue) ； 陳映如(Ying-Ju Chen) ； 楊遠波(Yuen-Po Yang)

《Botanical Studies》 53卷2期 (2012/04) Pp. 243-254

摘要

紅樹科紅樹林植物的枝稍具有圓形或扁平之托葉，緊密包圍著幼葉與頂芽。此托葉向軸面基部的指狀腺體分泌出明顯可見之樹脂狀至乳狀物質浸潤幼芽。本文首次系統性地觀察及比較本科紅樹林植物的18個分類群之托葉與指狀腺體的形態與構造。托葉內三種形態的厚壁異形細胞（細蕊紅樹與紅樹屬）、發達的厚角組織或與表皮細胞外之厚角質層，提供了機械性支持的結構基礎。數十個至數百個（35-580）似手指狀之指狀腺體聚集呈特定的形狀，具屬的專一性：紅茄苳屬呈長方形至梯形、細蕊紅樹屬和水筆仔屬為三角形、紅樹屬則呈帶狀。各托葉內指狀腺體的排數、總數與指狀腺體的個別大小，在各分類群並不相同，具分類價值。依據托葉和指狀腺體的特徵顯示細蕊紅樹屬和水筆仔屬的關係最接近，而紅樹屬則可能呈現較後起的特徵。本群植物的指狀腺體儘管在形態上呈現短柄桿狀（紅茄苳屬），長柄桿狀（細蕊紅樹屬和水筆仔屬）或無柄漸尖桿狀（紅樹屬），但其解剖構造均為標準型。此腺體的中心軸由細長的薄壁細胞構成，其外圍似柵狀的薄壁表皮細胞具分泌功能，與中心薄壁細胞呈垂直排列。由托葉所具的結構與機械性的保護功能，和其內指狀腺體的生理浸潤作用，可能對此紅樹林植物的頂芽提供了重要的保護，以助其應付嚴酷的環境。

關鍵字

解剖 ； 紅茄苳屬 ； 細蕊紅樹屬 ； 指狀腺體 ； 水筆仔屬 ； 紅樹林 ； 紅樹屬 ； 標準型 ； 厚壁細胞 ； 托葉

並列摘要

One characteristic possessed by the entire mangrove Rhizophoraceae is the strong enclosure of its young shoots by conspicuous rounded or flattened stipules. Young leaves are conspicuously immersed in resinous to milky exudates from colleters (multicellular external secretory emergences) located at the adaxial stipule bases. We systematically studied and compared morphological and structural features of stipules and their colleters from 18 taxa of the mangrove Rhizophoraceae. Three types of sclereid idioblasts (Ceriops and Rhizophora), collenchymas, and thick cuticles, were found to provide a structural basis for the mechanical support of stipules. Several to hundreds (35-580) of finger-like colleters aggregate into genus-specific shapes: rectangular to trapezoidal (Bruguiera), triangular (Ceriops and Kandelia), or as a band (Rhizophora). Number of rows, total number of colleters per stipule, and their individual size, also vary by taxon, and have taxonomic value. All colleters of this subfamily are considered anatomically 'standard', regardless of whether they appear as short-stalked rods (Bruguiera), long-stalked rods (Ceriops, Kandelia) or acuminate rods (Rhizophora, no stalk). Colleters in these taxa are comprised of a central axis of slender, elongated cells and an outer palisade- like epidermis, with a secretory function, perpendicular to the axis. Based on stipule and colleter characteristics, Ceriops and Kandelia are closely related, but Rhizophora shows more derived features. The structural and mechanical protection provided by stipules and colleter exudates may help shield the young shoots of these mangrove plants from their harsh environments.

並列關鍵字

Anatomy ； Bruguiera ； Ceriops ； Colleter ； Kandelia ； Mangroves ； Rhizophora ； Sclereid ； Standard type ； Stipule