Overcup Oak Quercus lyrata Walter    Synonyms: Over-cup Oak, Swamp Post Oak.
Kingdom Plantae   >   Division Tracheophyta   >   Class Magnoliopsida   >   Order Fagales   >   Family Fagaceae   >   Genus Quercus   


Overcup Oak is very uncommon in Maryland. Records are mainly from the coastal plain.

Overcup Oak is a medium to large, slow-growing tree that is "restricted to poorly-drained lowlands of the Southern coastal plain and major rivers of the South and mid West" (Stein, et al., 2003). It is highly flood tolerant.


Overcup Oak is unusual because of the way the cup of the acorn almost completely encloses the nut itself, explaining its common name. The leaf blade is narrow and oblong, with deep sinuses. The species epithet "lyrata" refers to the lyre shape of many of the leaves. The bark is gray, with deep furrows and scaly ridges or plates. The acorns are small and buoyant, which allows them to be distributed by flood waters in the lowland habitat of this tree. Although Overcup Oak is a member of the White Oak group, whose acorns generally ripen, fall off, and germinate in the autumn of the year they were formed, Overcup Oak acorns have a longer dormant period. This delay in germination helps give an acorn that has fallen into flood waters time to find a suitable spot downstream for germination.

Where to find:

Large trees can be found growing in the floodplain of Tuckahoe Creek in Adkins Arboretum.

In the late 20th century, a single Overcup Oak was present at Bear Island, near Great Falls along the Potomac River in the Piedmont of Montgomery County (J. and B. Hill, pers. obser.), but that tree has since died.

There are 13 records in the project database.

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Overcup Oak in Anne Arundel Co., Maryland (4/6/2011). Photo by Bill Harms. (MBP list)

Leaves of Overcup Oak in Biedler Forest, South Carolina (4/25/2012). Photo by Will Stuart. (MBP list)

Overcup Oak in Caroline Co., Maryland (6/21/2020). (c) Wayne Longbottom, some rights reserved (CC BY-NC). Photo by Wayne Longbottom. (MBP list)

The trunk of an Overcup Oak in Wood Co., Texas (11/28/2012). Photo by Sonnia Hill. (MBP list)

Overcup Oak in Caroline Co., Maryland (5/14/2018). Photo by Wayne Longbottom. (MBP list)

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