diff --git a/src/VirtualLeafpar.tmpl b/src/VirtualLeafpar.tmpl
--- a/src/VirtualLeafpar.tmpl
+++ b/src/VirtualLeafpar.tmpl
@@ -13,6 +13,7 @@ label = / label
 label = <b>Cell mechanics</b> / label
 T = 1.0 / double
 lambda_length = 100. / double
+yielding_threshold = 4. / double
 lambda_celllength = 0. / double
 target_length = 60. / double 
 cell_expansion_rate = 1. / double