Wood Anatomy of Gesneriaceae

Qualitative and quantitative data are presented for woods of 37 species representing 11 genera; most species included represent a maximal degree of woodiness for the family, and herbaceous groups are mostly omitted. Growth rings are absent or nearly so. Vessel elements have simple perforation plates (except for Kohleria elegans) and alternate circular or oval pits of various sizes on vessel-vessel walls (often laterally elongate, often with gaping apertures, on vessel-parenchyma and vessel-septate fiber interfaces). Grooves interconnect pit apertures in vessels of four genera. Vessels are grouped, usually in radial chains, to a moderate extent. Tyloses are present. Imperforate tracheary elements are libriform fibers or (Coronanthera) fiber tracheids with vestigial borders on pits. Septa are present in imperforate tracheary elements of most species, but in most species of Cyrtandra, septate fibers occur only near vessels. Uniseriate rays are present in some species, but in most species rays are muItiseriate only or are absent altogether. Vascular and vasicentric tracheids are absent. In Cyrtandra, wood with multiseriate rays can be demonstrated to be rayless earlier in ontogeny. Crystals are present in rays and in septate fibers of a few species. Storying is present in a few species. All features of wood reflect the mesic habitats characteristic of Gesneriaceae, but moderate degrees of xeromorphy are illustrated by species in which narrow vessels, grouped vessels, and grooves in vessel walls occur. The wood anatomy of Drymonia reflects its vining habit. Raylessness may indicate secondary woodiness in Besleria and Cyrtandra. Wood anatomy of Gesneriaceae is consonant with a hypothesis that the family is closely related to Acanthaceae, Scrophulariaceae, and other families of Scrophulariales