Revisiting the anatomy of the monocot cambium, a novel meristem

Philip Simpson,Alexei Oskolski,Joanna Jura-Morawiec

doi:10.1007/s00425-021-03654-9

Abstract

Main conclusionThe monocot cambium is semi-storied, and its cells do not undergo rearrangement.The monocot cambium is a lateral meristem responsible for secondary growth in some monocotyledons of Asparagales. It is an unusual meristem, not homologous with the vascular cambia of gymnosperms and non-monocotyledonous angiosperms. Owing to the limited information available on the characteristics of this meristem, the aim of this study was to survey the structure of the monocot cambium in order to clarify the similarities and dissimilarities of this lateral meristem to the vascular cambium of trees. Using the serial sectioning analysis, we have studied the monocot cambium of three species of arborescent monocotyledons, i.e., Quiver Tree Aloe dichotoma, Dragon Tree Dracaena draco, and Joshua Tree Yucca brevifolia, native to different parts of the world. Data showed that in contrast to the vascular cambium, the monocot cambium is composed of a single type of short initials that vary in shape, and in tangential view display a semi-storied pattern. Furthermore, the cells of the monocot cambium do not undergo rearrangement. The criteria used in identifying monocot cambium initial cell are also discussed.

Highlights

During the course of evolution, the two secondary vascular meristems have developed for the radial growth of plant organs, namely the vascular cambium and the monocot cambium (Spicer and Groover 2010; Carlquist 2012)
Anticlinal divisions were not observed in investigated monocot cambium cells
Whereas the vascular cambium has two types of cambial initials, the fusiform and ray initials, which in tangential view appear to be arranged in non-storied, semi-storied, storied or double-storied patterns (Larson 1994; Kojs et al 2004a, b), the monocot cambium has only one type of initials (Cheadle 1937). These initials may be arranged in a semi-storied pattern

Summary

Introduction

During the course of evolution, the two secondary vascular meristems have developed for the radial growth of plant organs, namely the vascular cambium and the monocot cambium (Spicer and Groover 2010; Carlquist 2012). Both meristems are concentric and contain cambial initials that undergo periclinal divisions, and these, in turn, differentiate to produce secondary vascular tissues The vascular cambium and monocot cambium have similar roles in radial growth but differ in establishment of the cambial cylinder, cell composition and the nature of their derivatives

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