by Steven D. Glenn
Not peer reviewed
Last modified: 01/25/2013
Quercus L., Sp. Pl. 2: 994. 1753.
LECTOTYPE: Q. robur L. (see Britton & A.Br., Ill. Fl. N. U. S. ed. 2. 1: 616. 1913).
Macrobalanus (Oerst.) Schwarz, Nétizbl. Bot. Gart. Mus. Berlin, 13: 8. 1936.
TYPE: not designated.
Key to the species of Quercus
1. Leaf margins entire...2.
1. Leaf margins with lobes or teeth...4.
2. Leaves broadly obovate, broadest near top...Quercus marilandica
2. Leaves linear-oblong, broadest near middle...3.
3. Leaves permanently and evenly pubescent beneath, 2.8 cm wide or more...Quercus imbricaria
3. Leaves glabrous beneath (or few scattered hairs along main vein), 2.5 cm wide or less...Quercus phellos
4. Leaf lobes/teeth without bristle tips...5.
4. Leaf lobes/teeth with bristle tips...12.
5. Leaves with some lobes...6.
5. Leaves with teeth only...9.
6. Leaf undersides glabrous; current season twigs glabrous...Quercus alba
6. Leaf undersides hairy; current season twigs hairy...7.
7. Most leaves with only 2 lobes toward apex, undersides with golden-yellow tomentum...Quercus marilandica
7. Most leaves with more than 2 lobes, underside tomentum not golden-yellow...8.
8. Leaf blade with a few deep sinuses (extending more than ˝ the distance to the midrib); older twigs with corky wings/ridges; rare non-native escape...Quercus macrocarpa
8. Leaf blade regularly lobed; twigs without corky wings/ridges; frequent native in sandy coastal areas...Quercus stellata
9. Bark of 3 year-old and older twigs/branches exfoliating in large patches; acorn peduncle over 20 mm in length...Quercus bicolor
9. Bark of twigs/branches not exfoliating; acorn peduncle less than 20 mm in length...10.
10. Leaf underside with tufts of spreading hairs along midvein, with scattered, irregular, 2-4-rayed, microscopic hairs; bark deeply furrowed with large ridges; widespread throughout our area...Quercus montana
10. Leaf undersides without tufts of spreading hairs along midvein, with scattered to dense, 6-10-rayed, microscopic hairs; bark scaley...11.
11. Leaves with 9 or more pairs of lateral veins; tall tree; occurring in inland, isolated limestone or calcareous areas...Quercus muhlenbergii
11. Leaves with 8 or fewer pairs of lateral veins; colonial shrub; occurring in coastal sandy areas as well as occasional inland dry sites...Quercus prinoides
12. Most leaves with only 2 lobes toward apex, undersides with golden-yellow tomentum...Quercus marilandica
12. Most leaves with more than 2 lobes, underside tomentum not golden-yellow...13.
13. Leaf undersides uniformly covered with white to gray tomentum...14.
13. Leaf underside with scattered brown to tan tomentum...15.
14. Most leaf blades 10 cm or less in length; terminal leaf lobe broadly triangular; shrub or small tree...Quercus ilicifolia
14. Most leaf blades 10 cm or more in length; terminal leaf lobe elongate, narrow, somewhat hooked; large tree...Quercus falcata
15. Terminal buds uniformly pubescent...Quercus velutina
15. Terminal buds glabrous or pubescent only on distal ˝...16.
16. Terminal buds pubescent only on distal ˝...17.
16. Terminal buds glabrous...18.
17. Leaf sinuses extending less than ˝ distance to midrib; acorn cup shallow, saucer-shaped...Quercus rubra
17. Leaf sinuses extending more than ˝ distance to midrib; acorn cup turbinate...Quercus coccinea
18. Leaf sinuses extending less than ˝ distance to midrib, underside glabrous...Quercus rubra
18. Leaf sinuses extending more than ˝ distance to midrib, underside with distinct tufts of hairs in the vein axils...Quercus palustris
List of Quercus Species
- Quercus alba
- Quercus bicolor
- Quercus cerris - excluded species
- Quercus coccinea
- Quercus falcata
- Quercus ilicifolia
- Quercus imbricaria - excluded species
- Quercus macrocarpa
- Quercus margaretta - excluded species
- Quercus marilandica
- Quercus montana
- Quercus muehlenbergii
- Quercus palustris
- Quercus phellos
- Quercus prinoides
- Quercus robur
- Quercus rubra
- Quercus stellata
- Quercus velutina
- Quercus x brittonii (Q. ilicifolia × Q. marilandica)
- Quercus x bushii (Q. marilandica × Q. velutina)
- Quercus x faxonii (Q. alba × Q. prinoides)
- Quercus x filialis (Q. phellos x Q. velutina)
- Quercus x giffordii (Q. ilicifolia x Q. phellos)
- Quercus x hawkinsii (Q. rubra x Q. velutina)
- Quercus x heterophylla (Q. phellos × Q. rubra)
- Quercus x jackiana (Q. alba × Q. bicolor)
- Quercus x rehderi (Q. ilicifolia × Q. velutina)
- Quercus x robbinsii (Q. coccinea x Q. ilicifolia)
- Quercus x rudkinii (Q. marilandica × Q. phellos)
- Quercus x saulei (Q. alba × Q. montana)
A large world-wide genus of approximately 400 species of deciduous or evergreen trees and shrubs.