Grobbelaar, NathanaelRobbertse, P.J. (Petrus Johannes), 1932-2012-06-052012-06-052012-05N. Grobbelaar & P.J. Robbertse, Cycad collicles (“leaflet nodules”), South African Journal of Botany, vol. 80, no. 5, pp. 77-80 (2012), doi: 10.1016/j.sajb.2012.02.0080254-6299 (print)1727-9321 (online)10.1016/j.sajb.2012.02.008http://hdl.handle.net/2263/19094The presence of small knobs/nodules found on the adaxial leaflet surface of some Encephalartos species was investigated in 134 cycad species of nine genera. The knobs, referred to as collicles, were found to be the result of connecting mucilage canal ‘bridges’ over vascular bundles, connecting mucilage canals situated between adjacent parallel vascular bundles. Collicles were found on some Encephalartos species only and not always on all individuals of the same species. The possible taxonomic value of these collicles is discussed.en© 2012 SAAB. Published by Elsevier B.V. All rights reserved.ColliclesLeaflet anatomyMucilage canalsEncephalartos -- Diseases and pestsLeaves -- Diseases and pestsCycads -- Diseases and pestsPostprint Article