Historical clue formulations

• Leaf opening — 2024-07-21
• Leaf pore — 2024-05-05
• Plant pore — 2022-09-04
• Opening in a leaf — 2021-07-31
• Botanical opening — 2020-03-20
• Botanical opening — 2018-12-16
• Photosynthesis opening — 2016-10-07
• Leaf pore — 2016-02-10
• Botanical opening — 2014-11-13
• Tiny opening in a leaf — 2010-09-03
• Leaf opening — 2010-03-23
• Leaf pore — 2007-04-08
• Botanical opening — 2005-11-25
• Zoological opening — 2003-03-23
• Leaf opening — 2001-09-19
• Plant pore — 2000-03-26
• Leaf pore — 1998-10-18
• Leaf's breathing orifice — 1998-07-22
• Pore in a leaf — 1996-11-06
• Leaf opening — 1996-09-13
• Leaf aperture — 1996-05-14
• Botanical opening — 1996-02-21