Quercus macrocarpa
Bur Oak

Pistillate Flower Top

Intersection Highways #9 and #247

Each pistillate flower is enclosed in a scaly, cup-like involucre called a cupule and each pistillate flower contains three styles.  The cupule is derived from inflorescence axes as described in this excerpt from an article by Alastair D. Macdonald:

Each female flower of Quercus macrocarpa terminates a second-order inflorescence axis and is surrounded by a continuous cupule. The cupule first forms as two primordia in the axils of each of the two transversal second-order bracts. These cupular primordia represent third-order inflorescence branches. The cupule primordia become continuous about the pedicel by meristem extension.

 Macdonald, A. D. (2011).  Inception of the cupule of Quercus macrocarpa and Fagus grandifolia.  Canadian Journal of Botany, 57(17), 1777-1782

Fagaceae: Answers to key questions in Budd's Flora leading to this family. 

shrubs or trees; NOT [herbs]

male flowers, at least, in catkins

flowers with only one floral ring, with sepals but not petals

styles 3 or more; NOT [styles2]

fruit an acorn

seeds without a tuft of hairs