Wood Anatomy of Acanthaceae: A Survey

Abstract

ABSTRACfQualitative and quantitative wood features are reported for 38 species representing 22 genera, including the scandent genera Mendoncia and Thunbergia. Woods of Acanthaceae are characterized by relatively narrow vessels with simple perforation plates and alternate lateral wall pitting, septate libriform fibers, scanty vasicentric axial parenchyma, rays both multiseriate and uniseriate, erect ray cells abundant in rays (some species rayless or near-rayless), numerous small crystals or cystoliths in ray cells in a few genera (first documented reports of both characters in woods of Acanthaceae), and nonstoried structure. This constellation of features is very closely matched by woods of Gesneriaceae, Scrophulariaceae, Pedaliaceae, Martyniaceae, Bignoniaceae, and Myoporaceae (families listed in order ofdecreasing resemblance). Narrowness ofvessels in tropical Acanthaceae appears related to understory ecology. A few species in warm and seasonally dry areas have narrow, short vessel elements numerous per unit transection. Vasicentric tracheids occur in two nonscandent genera in dry areas. Vessel grouping is roughly proportional to dryness of habitat. Thunbergia alata, T. laurifolia, and all collections of Mendoncia have interxylary phloem (first report for Mendoncia). That feature, plus presence of occasional acicular crystals in rays and axial parenchyma and presence of large gelatinous fibers in phloem ally Mendoncia closely with Thunbergia, and Mendonciaceae is not justified for this and other reasons. Species of Thunbergia differ among themselves, and T. erecta and T. holstii resemble shrubby Acanthaceae more than they do Mendoncia in wood features. Thunbergia thus should not be segregated from Acanthaceae.

Wood anatomy and hydraulic architecture of stems and twigs of some Mediterranean trees and shrubs along a mesic-xeric gradient

“…Notwithstanding the low vessel frequency in stemwood, the mesic O. carpinifolia also seemed to have high conductive safety because of the high vessel frequency, grouping and low vulnerability. Although its speculative nature due to the lack of an absolute hydraulic basis, the vulnerability index is commonly used to indicate adaptation to xeric (values \1) or mesic (values[1) conditions (Carlquist 1977(Carlquist , 1992Psaras and Sofroniou 1999). In twigwood of the eight examined species, values of vulnerability of 0.01-0.06 accord with the occurrence of greater tensions in water columns at upper levels in terminal twigs than at lower levels in older branches and stems (Scholander et al 1965;Poole 1994;Fisher et al 2007).…”

Living cells in wood. 2. Raylessness: histology and evolutionary significance

“…Libriform fibres sheathe the large‐diameter vessels that are probably vulnerable to breakage in a liana and thus lessen vessel rupture. The lateral plate‐like extensions of the fibre sheaths is unusual in Acanthaceae (Carlquist & Zona, ). Some of these plates are tangentially intercontinuous, which would provide a rigidity counterproductive in a liana (Fig.…”

“…Acanthaceae: Beloperone crenata Standl., Diapedium assurgens , Jacobinia spp., Thunbergia alata (Carlquist & Zona, ).…”

Floral anatomy of Thomandersia (Lamiales), with particular reference to the nature of the retinaculum and extranuptial nectaries

“…Lu, 1990). Therefore, their absence from many Acanthaceae, like the absence of staminodes and vascular bundles in the septum of the gynoecium in this family, may be indicative of its highly derived position (Carlquist & Zona, 1988; Endress, 2001). Acanthaceae, together with Lamiaceae, Orobanchaceae, Mimulus and Paulownia , is sometimes suggested to form a group nested within the rest of Lamiales including Thomandersia (Endress, 2001; Bremer et al ., 2002).…”