Wood Anatomy of Caryophyllaceae: Ecological, Habital, Systematic, and Phylogenetic Implications

Abstract

Wood of Caryophyllaceae is more diverse than has been appreciated. Imperforate tracheary elements may be tracheids, fiber-tracheids, or libriform fibers. Rays may be uniseriate only, multiseriate only, or absent. Roots of some species (and sterns of a few of those same genera) have vascular tissue produced by successive cambia. The diversity in wood anatomy character states shows a range from primitive to specialized so great that origin close to one of the more specialized families of Chenopodiales, such as Chenopodiaceae or Amaranthaceae, is unlikely. Caryophyllaceae probably branched from the ordinal clade near the clade's base, as cladistic evidence suggests. Raylessness and abrupt onset of multiseriate rays may indicate woodiness in the family is secondary. Successive cambia might also be a subsidiary indicator of secondary woodiness in Caryophyllaceae (although not necessarily dicotyledons at large). Although a small shrub, Gymnocarpos may be primitively woody, and because that genus appears primitive in many wood features the family as a whole may derive from woody ancestors, despite apparent secondary woodiness in many phylads. Systematic distribution of wood character states in the family corresponds closely to the Pax and Hoffmann system of three tribes and their progressive degrees of specialization (Paronychieae, Alsineae, Sileneae). Wood data support the idea that Caryophyllaceae represent a branch from near the base of the order Caryophyllales. Wood of Caryophyllaeeae is highly xeromorphic, comparable in quantitative vessel features to wood of desert shrubs; insular species have less xeromorphic wood. Instances of storying and druse presence in axial and ray parenchyma are newly reported for the family, as is the inverted orientation of xylem, phloem, and periderm produced by a cambium at the periphery of the pith in Dianthus caryophyllus.