Taxonomic significance of trichomes in the genus Acanthopsis Harv. (Acanthaceae, tribe Acantheae) Author Steyn, Hester M. National Herbarium, South African National Biodiversity Institute, Private Bag X 101, Pretoria 0001 (South Africa) Author Van Wyk, Abraham E. H. G. W. J. Schweickerdt Herbarium, Department of Plant and Soil Sciences, University of Pretoria, Pretoria 0002 (South Africa) h.steyn@sanbi.org.za text Adansonia 2021 3 2021-07-12 43 14 163 176 journal article 5513 10.5252/adansonia2021v43a14 c1d60eac-0ec8-480e-b297-1a8e85dd5574 1639-4798 5092022 KEY TO THE DIFFERENT TRICHOME TYPES ON LEAVES AND FLORAL BRACTS OF ACANTHOPSIS HARV. : 1a. Trichomes non-glandular ....................................................................................................................... 2 1b. Trichomes glandular .............................................................................................................................. 5 2a[1]. Trichomes relatively thin-walled with a broad lumen (> ⅓ of cell diameter); uni- or multicellular; surface ornamented ........................................................................................................................................... 3 2b. Trichomes thick-walled with a narrow lumen (<¼ of cell diameter); uni- or multicellular; surface smooth or with helical pattern ............................................................................................................................ 4 3a[2]. Trichomes unicellular ................................................................................................................... Type A 3b. Trichomes multi-cellular; nodes often slightly swollen .................................................................... Type B 4a[2]. Trichomes unicellular ..................................................................................................................... Type C 4b. Trichomes multi-cellular; nodes distinctly swollen .......................................................................... Type D 5a[1]. Trichomes sessile or subsessile to short (usually < 200 µm long); stalk, if present, 1- or 2(3)-celled .......... 6 5b. Trichomes long (nearly always> 250 µm ); stalk 3-celled................................................................. Type G 6a[5]. Trichomes sessile or subsessile; stalk, if present, 1-celled ................................................................. Type E 6b. Trichomes short; stalk 2 (or 3)-celled............................................................................................... Type F