Abstract:Abstract: Misunderstandings about secondary structures of angiosperms are found in some botany textbooks. Firstly, an annual ring in tangential sections of woods (secondary xylems) has a reverse V-shape, whereas the structure is wrongly described as V-shaped in almost all the textbooks. Secondly, in transverse sections of a few years old stems, there are, outside the vascular cambium, some inverted triangle-shaped structures that are usually regarded as phloem rays or neglected in textbooks. In fact, however, they are the extended external parts of pith rays due to secondary growth. Thirdly, in cross sections of second growing roots, there are also inverted triangle shapes that are actually secondary rays, whereas these structures are neglected or recog-nized as a phloem ray in some botany textbooks. Finally, some model figures showing periderm transverse sections are often incorrectly labelled or drawn, which should be analysed to help students better understand the origin and development of periderm. In addition, two exploratory experiments are designed to tell students how to identify secondary structures and determine organ types based on structure-function relationships.
引用本文:
黎维平. 茎和根几个次生结构的探讨——植物学教材质疑 (九)[J]. 生命科学研究, 2022, 26(4): 370-376.
LI Wei-ping. Discussion of Some Secondary Structures of Stems and Roots
Questioning Botany Textbooks (Ⅸ). Life Science Research, 2022, 26(4): 370-376.