The progressive and ancestral traits of the secondary xylem within Magnolia clad – the early diverging lineage of flowering plants

Abstract

The qualitative and quantitative studies, presented in this article, on wood anatomy of various species belonging to ancient Magnolia genus reveal new aspects of phylogenetic relationships between the species and show evolutionary trends, known to increase fitness of conductive tissues in angiosperms. They also provide new examples of phenotypic plasticity in plants.The type of perforation plate in vessel members is one of the most relevant features for taxonomic studies. In Magnolia, until now, two types of perforation plates have been reported: the conservative, scalariform and the specialized, simple one.In this paper, are presented some findings, new to magnolia wood science, like exclusively simple perforation plates in some species or mixed perforation plates -simple and scalariform in one vessel member. Intravascular pitting is another taxonomically important trait of vascular tissue. Interesting transient states between different patterns of pitting in one cell only have been found. This proves great flexibility of mechanisms, which elaborate cell wall structure in maturing tracheary element. The comparison of this data with phylogenetic trees, based on the fossil records and plastid gene expression, clearly shows that there is a link between the type of perforation plate and the degree of evolutionary specialization within Magnolia genus.

Early spring flowers rely on xylem hydration but are not limited by stem xylem conductivity

“…Maximum vessel lengths were determined from previous publications ( Alnus , Tognetti & Borghetti (1994); Salix , Savage & Cavender‐Bares (2011); Prunus , Jeje & Zimmermann (1981), Scholz et al . (2013); Rhododendron , Cordero & Nilsen (2002); Magnolia , Wróblewska, 2015) and confirmed with the air injection method when possible. The water potentials of the cut branches were relaxed by placing the branches in a bucket of water and covering them with black plastic bags for several hours before taking measurements.…”

“…Branches were cut underwater two maximum vessel lengths away from the segment selected. Maximum vessel lengths were determined from previous publications (Alnus, Tognetti & Borghetti (1994) Cordero & Nilsen (2002); Magnolia, Wróblewska, 2015) and confirmed with the air injection method when possible. The water potentials of the cut branches were relaxed by placing the branches in a bucket of water and covering them with black plastic bags for several hours before taking measurements.…”

Drought Effects on Vessel Plasticity of Two Endemic <em>Magnolia</em> Species in the Tropical Montane Cloud Forests of Eastern Mexico

“…Diffuse-porous wood is an anatomical adaptation that grants a high performance in hydraulic conductance during drought events in TMCFs [32]. Magnolia's wood is mainly characterized as a diffuse-porous wood where xylem vessels maintain the same diameter and are evenly distributed within a growth ring [33,34]. We studied the drought effect on the annual tree-rings width (TRW) of individual trees in two populations of Mexican Magnolia species (M. vovidesii and M. schiedeana; see descriptions in Dieringer and Espinosa [35] and Vázquez-García et al [36]).…”