Summary. The tendrils of Virginia creeper (Parthenocissus quinquefo- lia) do not coil around their supports. Rather, they adhere to supporting objects by flattening against the support surface and secreting an adhe- sive compound which firmly glues the tendril to the support. In this study, microscopic and immunocytochemical techniques were utilized to determine the nature of this adhesive. Following touch stimulation, epi- dermal cells of the tendril elongate toward the support substrate, becom- ing papillate in morphology. Following contact with the support surface, an adhesive is produced at the base of the papillate cells. The adhesive appears as a highly heterogeneous, raftlike structure and consists of pecti- naceous, rhamnogalacturonan (RG) I-reactive components surrounding a callosic core. In addition, more mobile components, composed of ara- binogalactans and mucilaginous pectins, intercalate both the support and the tendril, penetrating the tendril to the proximal ends of the papillate cells. Following adherence to the support, the anticlinal walls of the papillate cells are devoid of RG I side-chain reactivity, indicating that extensive debranching of RG I molecules has taken place. Furthermore, a large amount of RG I backbone reactivity was observed in the contact area. These results may indicate that the debranched RG I molecules dif- fuse into and permeate the contact region, forming an integral part of the adhesive compound. These results indicate that Virginia creeper adheres to objects by a composite adhesive structure consisting of debranched RG I, callose, and other, less-well characterized mucilaginous pectins and that this structure subsequently becomes lignified and very weather- resistant upon the ultimate senescence of the tendril. Keywords: Parthenocissus quinquefolia; Adhesive; Tendril; Vine; Rhamnogalacturonan I; Immunocytochemistry. Abbreviations: AGP arabinogalactan protein; RG I rhamnogalacturonan I fraction. Introduction Vines have evolved several different mechanisms for uti- lizing stationary objects in order to compete for sunlight without investing energy in a large woody trunk (Darwin 1875, Jaffe and Galston 1969). The three most prominent climbing mechanisms are twining stems, coiling tendrils, and adhesive organs (tendrils or adventitious roots). A plant may also use more than one of these mechanisms to scale an object. For example, redvine (Brunnichia ovata) produces coiling tendrils that, once securely wrapped around an object, produce adhesive compounds that ce- ment the tendril in place (Meloche and Vaughn 2008). Twining stems and coiling tendrils are limited in the di- ameter of objects they can ascend (Scher et al. 2001; Vaughn pers. obs.), whereas vines which use the adhesive mode of attachment are able to climb large-diameter and flat objects which pure tendril climbers cannot ascend. Despite the large number of species using adhesives alone or in conjunction with coiling, there have been few studies on these tendrils or this very effective adhesive (Endress and Thomson 1976, 1977), one that must support many kilograms of vine as it ascends an object. Several members of the genus Parthenocissus (most no- tably Boston ivy and Virginia creeper) possess small, forked tendrils that develop flattened adhesive discs at their tips upon contact with a surface suitable for attach- ment. Earlier studies have suggested that there is a sub- stantial amount of polyphenols present in the cells of the young (nonadhered) tendril (Endress and Thomson 1976) and that the adhesive substance in fully matured tendrils is most likely composed of an acidic mucopolysaccharide (Endress and Thomson 1977). The reagents used in those studies (e.g., ruthenium red, thorium) are general ones that recognize classes of compounds, not individual com- ponents, however. Since that time, significant advances in our ability to identify the components of plant cell walls Structural and immunocytochemical characterization of the adhesive tendril of Virginia creeper (Parthenocissus quinquefolia [L.] Planch.) A. J. Bowling, K. C. Vaughn Southern Weed Science Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Stoneville, Mississippi Received 27 June 2007; Accepted 30 August 2007; Published online 18 April 2008 © Springer-Verlag 2008 Protoplasma (2008) 232: 153–163 DOI 10.1007/s00709-008-0287-x PROTOPLASMA Printed in Austria Correspondence: Kevin C. Vaughn, USDA-ARS-SWSRU, P.O. Box 350, Stoneville, MS 38776, U.S.A. E-mail: Kevin.Vaughn@ars.usda.gov