Historical clue formulations

• Prickly seedcase — 2022-01-24
• Prickly covering of a seed — 2021-01-24
• Prickly husk — 2019-08-02
• Prickly seedcase — 2012-02-16
• Sticky seedcase — 2011-06-19
• Seedcase that inspired Velcro — 2011-04-24
• Prickly husk — 2007-11-20
• Prickly seed cover — 2007-03-12
• Forest sticker — 2006-05-07
• Sticker — 2004-03-07
• Prickly husk — 2003-04-01
• Sticker — 2002-07-12
• Plant sticker — 2001-09-25
• Prickly seedcase — 2001-02-28
• Clingy seedpod — 2000-03-10