Wood and Stem Anatomy of Menispermaceae
Qualitative and quantitative data are presented for 17 collections of 15 species representing 14 genera. One species is a shrub (Cocculus laurifolius), one a subshrub (C. trilobus), and the remainder are lianas. Successive cambia are analyzed with respect to ontogeny and histology of products. Whether any Menispermaceae may or may not plesiomorphically lack successive cambia would require a more extensive survey of the family. Apomorphic absence of successive cambia is likely for species with subshrub growth forms (Cocculus trilobus, Menispermum canadense L.). Lianoid Menispermaceae share the following features: successive cambia, wide vessels, wide rays, high conductive area per transectional unit area, and tracheids as imperforate tracheary elements. All of these features are more common in lianoid dicotyledons than in their nonlianoid relatives. Vessels are solitary in the lianoid species on account of tracheid presence, but grouped in Cocculus trilobus, which has septate libriform fibers. Large multiseriate rays (combined with scarcity or absence of uniseriate rays) and storied structure of cambia (and cambial products that elongate little during maturation) characterize Menispermaceae and link the family to other families of Ranunculifiorae, as well as, in all likelihood, to the "paleoherb" families Aristolochiaceae, Lactoridaceae, Piperaceae, and Saururaceae.