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Quercus

 

Oak

KingdomPlantaePlants, but not fungi, lichens, or algae (from Stearn’s Botanical Latin)
SubkingdomTracheobiontaVascular plants—plants with a “circulatory system” for delivering water and nutrients
DivisionMagnoliophytaFlowering plants, also known as angiosperms
ClassMagnoliopsidaDicotyledons—plants with two initial seed leaves
SubclassRosidaeRoses, legumes, proteas, dogwoods, hydrangeas, mistletoes, euphorbias, grapes, many more
OrderFagalesBirch, she-oak, beech, walnut, bayberry, others
FamilyFagaceaeBeech familhy
GenusQuercusLatin for “oak”

About plant names...

The genus Quercus, Latin for “oak,” includes some 400 species worldwide, of which about 90 are found in North America.

Identification: Most species of oaks can be differentiated by examining leaf shapes, but it isn’t easy, since leaf shape in many oaks is extremely variable. Even a single tree can bear a wide range of leaf shapes. Try to assess “average” shape before making a determination based on leaf shape. If acorns are available, their shape is another important identifying characteristic. Many oaks have restricted ranges, another clue.

Following are some species comparisons:

 

Quercus (Oak)

(Quercus) · 5/29/2010 · Nashua River Rail Trail, Pepperell, MA
≈ 11 × 7" (27 × 18 cm) Species not yet identified

 
Quercus agrifolia

Quercus alba

Quercus bicolor
Common Name

Coast Live Oak

Eastern White Oak

Swamp White Oak
Plant These evergreens reach 20-82' (6-25 m), with trunks up to 4' (1.2 m) around. Trunks are short and the crowns are wide. 65-80' (19-24 m) tall, with a wide crown. 65-80' (19-24 m) tall.
Flowers Male flowers are catkins 1¾-4" (5-10 cm) long. Female flowers are ⅛" (5 mm) long, in clusters of one to three, barely noticeable.    
Leaves

Quercus (Oak) 


Dark green, thick, glossy, oval in shape, alternating, edged with sharp fibers. They are ¾-2½" (2-7 cm) × ⅜-1½" (1-4 cm).

 

Leaves 4-8" (10-20 cm) long. Leaf tips are rounded.

 

Leaves are 4-8" (10-20 cm) long, with many small rounded or slightly sharp lobes.
Stem Bark is smooth and gray-brown when the tree is young, becoming darker and somewhat furrowed later.    
Fruit Acorns are 1-1½" (2.5-3.8 cm) long and ⅜-½" (1-1.5 cm) wide, conical in shape. Acorns ¾-1" (1.9-2.5 cm) long. Bumpy cap covers about ¼ of the nut. Acorns are about 1" (2.5 cm) long, tan, with one or two on a long stalk.
Range/ Zones

Habitats Mixed evergreen forests, foothill woodlands, southern oak woodlands    
Type Wild Wild Wild
Occurrence Uncommon Common Common

 

 
Quercus coccinea

Quercus ilicifolia

Quercus macrocarpa
Common Name

Scarlet Oak

Bear Oak

Bur Oak
Plant Typically up to 80' (24 m) tall, irregular in shape. A shrub up to 15' (4.6 m) high. 70-80' (21-24 m) high.
Leaves

 

Leaves are deeply lobed, 3-7" (7.6-17 cm) long, with sharp hairlike tips. Shiny dark green.

 

Leaves are 2-5" (5-12 cm) long, shiny and dark green on top, whitish underneath.

 

About 6" (13 cm) long, sometimes up to 15" (38 cm), and very deeply divided. They are yellow-brown in the fall.
Fruit Acorns ½-1" (1.3-2.5 cm) long. The cap usually covers half of the nut. Acorns are ¼-½" (8.4-12 mm) long, dark brown, with cap covering about ⅓ of the nut.

 

Large 1-1½" (2.5-3.8 cm) acorns, half covered by the cap. Cap has a hairy or mossy fringe.
Range/ Zones

Type Wild Wild Wild
Occurrence      

 

 
Quercus prinus

Quercus rubra

Quercus suber
Common Name

Chestnut Oak

Northern Red Oak

Cork Oak
Plant Up to 80' (24 m) high. Up to 90' (27 m) tall. Up to 66' (20 m) tall.
Leaves

 

Leaves are 4-9" (10-22 cm) long, narrow, with many small, rounded indentations rather than lobes.

 

5-8" (12-20 cm) long, with 7-11 lobes and sharp-tipped leaves.

 

1½-2½" (3.8-6.3 cm) long, roughly oval, with a few rounded serrations. Drawing by M. Violante.
Fruit Acorns are large, 1-1½" (2.5-3.8 cm) long, dark brown, with thin, warty caps that cover about ⅓ of the nut. Acorns about 1" (2.5 cm) long, with shallow caps that cover about a fifth of the nut. Acorns are about 1" (2.5 cm) long, with large corky caps that cover about half of the nut.
Range/ Zones

Type Wild Wild Wild
Occurrence   Common  

 

 
Quercus velutina
Common Name

Eastern Black Oak
Plant 65-80' (19-24 m) tall.
Leaves

 

Leaves are 4-10" (10-25 cm) long, each with 5-7 lobes. Sun-facing leaves have deeper lobes than shade leaves.
Fruit Acorns are ½-¾" (1.3-1.9 cm) long, with caps that cover ⅓ to ½ of the nut.
Range/ Zones

USDA Zones: 3-9
Type Wild
Occurrence Common

 

Online References:

Quercus on Wikipedia

Quercus on Wikipedia

References:

Sibley, David Allen, The Sibley Guide to Trees, Alfred A. Knopf, 2009, DirrHardyTS

Little, Elbert L., National Audabon Society Field Guide to North American Trees, Eastern Region, Alfred A. Knopf, 1980

Quercus (Oak)

(Quercus) · 5/29/2010 · Nashua River Rail Trail, Pepperell, MA
≈ 14 × 9" (35 × 23 cm) Species not yet identified

Quercus (Oak)

Oak (Quercus) · 11/11/2008 · Acorn Trail, Great Brook State Park, Carlisle, MA
≈ 33 × 22" (84 × 56 cm) Species not yet identified

Quercus (Oak)

(Quercus) · 4/23/2010 · Nashua Rail Trail, Ayer, MA
≈ 6 × 4" (15 × 10 cm) Species not yet identified

Quercus description by Thomas H. Kent, last updated 16 Aug 2013.

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Quercus (Oak)

(Quercus) · 4/27/2010 · Nashua River Rail Trail, Pepperell, MA
≈ 4 × 3" (10 × 7.4 cm) Species not yet identified

Quercus (Oak)

(Quercus) · 8/8/2009 · Nashua River Rail Trail, Groton, MA
≈ 9 × 14" (23 × 35 cm) ID is dubious

Quercus (Oak)

(Quercus) · 1/8/2012 · Groton Place and Sabine Woods, Groton, MA
≈ 3 × 3½" (7.4 × 8.9 cm) Species not yet identified

Quercus (Oak)

Oak (Quercus) · 10/25/2009 · Nashua River Rail Trail, Nashua, NH
≈ 9 × 6" (22 × 14 cm) Species not yet identified

Quercus (Oak)

(Quercus) · 9/25/2010 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 6 × 9" (14 × 22 cm) Species not yet identified

Quercus (Oak)

(Quercus) · 5/31/2010 · Mt. Lebanon St., Pepperell, MA
≈ 3½ × 4" (9.8 × 9.9 cm) Species not yet identified

Quercus (Oak)

Oak (Quercus) · 10/25/2009 · Nashua River Rail Trail, Nashua, NH
≈ 8 × 5" (19 × 13 cm) Species not yet identified

Quercus (Oak)

(Quercus) · 9/29/2010 · Nashua River Rail Trail, Ayer, MA
≈ 12 × 8" (31 × 20 cm) Species not yet identified