“…Morphology of the testa cells of the seeds of Acanthaceae is variable and has been used in circumscribing taxa at different ranks ( Kippist, 1842 , Schaffnit, 1906 , Oehm, 1932 , Bremekamp, 1944 ; Hedrén, 1988 , Hedrén, 1989 , Graham, 1988 , Ensermu et al., 1992 , Immelman, 1990 , Balkwill et al., 1996 , Balkwill and Getiliffe Norris, 1988 , Balkwill and Campbell-Young, 1999 , Darbyshire, 2008 , Greuter and Rankin, 2010 , Darbyshire et al., 2011 , Rueangsawang et al., 2012 , Tripp et al., 2013 , Kiel and McDade, 2014 , Al-Hakimi and Latiff, 2015 ). For example, seeds of Ruellieae have spiral hygroscopic mucilaginous hairs ( Kippist, 1842 , Greuter and Rankin, 2010 , Duan, 2013 ).…”