Wood Anatomy of Calyceraceae and Valerianaceae, with Comments on Aberrant Perforation Plates in Predominantly Herbaceous Groups of Dicotyledons

Wood Anatomy of Placothira (Loasaceae)

“…Axial parenchyma is vasicentric scanty in Plakothira, whereas only diffuse (abundant to scarce), banded, and pervasive (parenchyma replaces all or large proportion of potential zones of imperforate tracheary elements) types have thus far been reported from Loasaceae (Carlquist 1984a). This would seem a very distinctive feature, because in many families of dicotyledons, axial parenchyma types vary relatively little.…”

“…If so, one would expect indicators ofpaedomorphosis in wood anatomy: persistence with little modification of metaxylem features into secondary xylem (Carlquist 1962), and attention is paid to this phenomenon in the present study.…”

“…The imperforate tracheary elements have pits with vestigial borders; although the borders are very small, these cells are termed fiber-tracheids here in accordance with the lAW A Committee on Nomenclature (1964). In other genera of Loasaceae, such as Eucnide and Fuertesia, border diameter can reach 5 J.Lm in imperforate tracheary elements, and those cells lie on the borderline between tracheids and fiber-tracheids (Carlquist 1984a). The genera of Loasaceae with vestigial borders on fiber-tracheid pits are all Southern Hemisphere genera: Loasa and Kissenia (sometimes cited as Fissenia).…”

“…A survey of wood anatomy of Loasaceae (Carlquist 1984a) included all of the woody genera known at that time. A year later, however, a new woody genus, Plakothira, was added to the family by Florence (1985).…”

“…Because there is a range in wood anatomy within Loasaceae in which distribution of certain features corresponds to the taxonomic system (Carlquist 1984a), some wood data pertinent to systematic placement of Plakothira are available.…”