茜草科7种木质藤本茎部异常构造

Abstract

茜草科是台湾低海拔次生林及阔叶林之优势科之一，缺乏木质藤本形成层变异资料。本研究目的探讨茜草科7种木质藤本茎形成层变异，绘制拍照横切面构造图、制作检索表以及描述茎部各部位构造，供野外采集调查及鉴定上之参考。本文归类出4种木质部形态，即深裂状有南投凉喉茶、红珠藤、羊角藤；两浅裂状为鸡屎藤；毛玉叶金花、拎壁龙为圆形；恒春钩藤为角状。除鸡屎藤外，其余6种均具内含韧皮部，恒春钩藤内含韧皮部四方形最为特殊。拎壁龙具不定根。红珠藤和羊角藤具木栓层构造。南投凉喉茶、鸡屎藤、毛玉叶金花、拎壁龙具火焰状次生韧皮部；次生韧皮部与次生木质部镶嵌在一起为南投凉喉茶、红珠藤和羊角藤。南投凉喉茶是唯一具有火焰状次生韧皮部、次生韧皮部与木质部镶嵌等2种特征且髓心偏一侧。 Rubiaceae are one of the dominant families in the broad leaved forest of Taiwan in low altitude, including some lianas. There was a paucity of the cambium variations of lianas in this family that affects the lianas identification correctly. The aims of this study are to identify the cambium variation of Rubiaceae seven liana stems, line drawings, photo the cross-section of stem structures, and make an indented key in order to aid the field survey. Four xylem types are found, including deeply lobe types such as Hedyotis hedyotidea, Morinda parvifolia and Morinda umbellate; two- lobed type as Paederia foetida; circular type as Mussaenda pubescens, Psychotria serpens, and Uncaria lanosa var. appendiculata belonging to angular type. Except Paederia foetida, six species develop including phloem. The specific character of Uncaria lanosa var. appendiculata about included phloem is square shape. Psychotria serpens develop adventitious root, and Morinda parvifolia and Morinda umbellata were together with thick phellem. Four species with flame secondary phloem are Hedyotis hedyotidea, Paederia foetida, Mussaenda pubescens, and Psychotria serpens. Secondary xylem and secondary phloem developing mosaic pattern are Hedyotis hedyotidea, Morinda parvifolia and Morinda umbellata. Only one species with flame secondary phloem and mosaic pattern is Hedyotis hedyotidea in which its pith is eccentric.