Vexillary aestivation involves the largest standard petal overlapping the wings and keel. Which term is this?

• A. Valvate
• B. Twisted
• C. Vexillary
• D. Imbricate

Answer: (C)

Aestivation refers to how petals come together in a flower bud. Vexillary aestivation is the pattern seen in papilionaceous flowers (like peas and beans) where the large standard petal sits on top and overlaps the two wing petals along the sides and the keel petals beneath. This creates the characteristic butterfly-like shape before opening. So, when the description says the largest standard petal overlaps the wings and keel, it matches vexillary aestivation. Other patterns describe different overlap relationships: valvate petals meet edge to edge without overlapping, imbricate petals overlap each other in a stepped way but not with a single dominant petal covering all, and twisted involves a spiral overlap.