Yellow foxglove 
Yellow Germander 
Yellow glandweed 
Yellow lion's mouth 
Yellow rattle 
Yellow Trumpet-Tree 
Yellow Trumpetbush 
Yellow-flowered skull cap 
Yellow-Vein Eranthemum 
Yellow-Vein Eranthemum 
Yellowseed false pimpernel 
Zaluzianskya divaricata 
Ziziphora capitata 
Ziziphora clinopodioides 
Ziziphora persica 
Ziziphora puschkinii 
Ziziphora taurica 
Ziziphora tenuior