The Anomalous Structure of Stems of Seven Rubiaceae Lianas

Abstract

Abstract 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 varia- tion 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 Un- caria lanosa var. appendiculata belonging to angular type. Except Paederia foetida, six species de- velop including phloem. The specific character of Uncaria lanosa var. appendiculata about in- cluded phloem is square shape. Psychotria serpens develop adventitious root, and Morinda parvi- folia 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, Mo- rinda parvifolia and Morinda umbellata. Only one species with flame secondary phloem and mo- saic pattern is Hedyotis hedyotidea in which its pith is eccentric.