毛莨科植物根结构的比较解剖研究

COMPARATIVE ANATOMICAL STUDIES ON ROOT STRUCTURE OF RANUNCULACEAE

对毛茛科(Ranunculaceae)36属65种植物的根结构进行了比较解剖研究。其根结构可分为5种类型:A.根仅为二原型。初生木质部为次生木质部管状分子所包围,无射线。如黄连属(Coptis)。B.根为二原型。次生木质部中射线狭窄,管状分子部分呈半圆形。如蓝堇草属(Leptopyrum)。C.根为二、三、四原型。次生木质部中的管状分子部分和射线均呈扇形。如升麻属(Cimicifuga)等。D.根中仅具少量次生木质部。D1.仅为二原型。如独叶草属(Kingdonia);D2.具二、三、四、五原型。如毛茛属(Ranunculus)等。E.无次生构造。E1.仅为二原型。如星果草属(Asteropyrum);E2.具二、三、四、五原型。如驴蹄草属(Caltha)。根据这些属植物的导管分子和植物其它部分(如心皮、叶柄及脉序)的比较解剖研究,可认为仅具二原型、次生木质部管状分子极发达或不发育的根部都属原始类型,如A型(黄连属)和E1型(星果草属)。根结构由原始到进化的演化途径可能为A→B→C→D2→E2以及E1→D1。

This paper deals with comparative studies of the root structure in 65 species of 36 gene- ra of Ranunculaceae. Five types of the root structure were recognized in these species. A. The roots, in which the primary xylem was surrounded by the tracheary elements of the secondary xylem and the ray was absent, were always diarchy, as seen in Coptit. B. The raps were nar- row and the tracbeary elements of the secondary xylem were semicircle in shape, and the roots were diarchy, as seen in Leptopyrum. C. The rays and tracheary elements of the secondary xylem were sector in shape, and the roots were di-, tri-, and tetrarchy, as seen in Cimicifuga, etc. D. There was a few secondary xylem in the roots. D1. Primary structure was diarchy, in Kingdonia. D2. The roots were di-, tri-, tetra- and pentarchy, in Ranunculuf etc. E. The se- condary structure was absent. E1. The roots were diarchy, in Asteropyrum. E2. They were di-, tri-, tetra- and pentarch, as seen in Caltha. According to comparative anatomical studies on the characteristics of the vessel elements and other parts of plant (carpel, petiole and vena- tion), the roots which were always diarchy whetber in older or young, and whether the tra- cheary elements of the secondary xylem well orless developed, could be considered as the most primitive type, for example: type A (Coptis) and type E1 (Asteropyrum). It would be con- cluded that the evolution of the root structure from primitive to specialized type was in the order from type A→B→C→D2→E2 and E1→D1 in Ranunculaceae.