arranged in three rows.
Botany. arranged in or characterized by three vertical rows.
Origin of tristichous
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
arranged in three rows, esp (of plants) having three vertical rows of leaves
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012