rubra – red (Latin)

Native range: NE North America

Leaves:

• alternate
• simple
• oblong
• 4.5–8.5” by 4–6”
• 7–11 loved, about halfway to middle
• depth of sinuses fairly regular
• lobes with bristle tips
• ends of lobes pointed rather than rounded - narrow down at the end (bases wedge-shaped)
• long petiole
• dark green above
• pale or gray below

Flowers:

• monoecious
• male flowers:
  • slender pendulous catkins
  • 6 stamens surrounded by tufts of hairs
• female on short stalks, 1 per cupule (sepal cup w/ 3 styles)

Fruit:

• acorn
• ovoid
• 3/4–1” (2–2.5 cm) long
• short stalked
• involucre hardens into a flat, thick, saucer-like cup that encloses 1/3 of nut

Other characteristics:

• deciduous tree
• up to 100 ft. tall and 2–3 ft. in diameter
• bark:
  • distinct flat gray areas w/ ridges & shallow furrows
  • old trunks brown-black w/ fissures
• leaves are pink-reddish when opening and red in fall

Relevant info:

• tallest and most rapidly growing of the oaks
• one of the most important ornamental and timber trees in Quercus
• Quercus rubra—stick it to ya! (in reference to pointed lobes with bristle tips)
• first bears fruit at 25 years
• acorns eaten by Native Americans, leached with ashes to remove bitter tannins
• state tree of New Jersey

Ecology & Adaptations:

• native from Nova Scotia to Pennsylvania, west to Minnesota and Iowa
• found in dry-mesic to mesic (moderately moist) sites
• in rich, mesic woods, on sandy plains, rock outcrops, stable inter-dunes, and at the outer edges of floodplains
• most common on north- and east-facing slopes
• lower and middle slopes, in coves, ravines, and on valley floors
• pollinated by wind
• seed dispersal:
  • primarily by birds and mammals
  • scatter-hoarders such as the gray squirrel are particularly important dispersal agents in some areas because they bury seeds and fail to recover many over the winter
  • mice and chipmunks move seeds up to 98 feet
  • blue jays transport seed from several hundred yards up to 3 miles
• vegetative regeneration:
  • commonly sprouts vigorously after plants are damaged or killed by fire or mechanical injury
  • sprouts grow from roots and epicormic buds beneath the bark of older oaks
• fire adaptation:
  • older, larger individuals often survive fire
  • young, small trees typically re-sprout vigorously from the stump or root collar
  • stem density often increased as fire promotes sprouting and reduces competition
  • more susceptible to fire than many other species of oak because tight, solid bark is typically more seriously damaged than rough, corky bark of species such as white oak
  • capable of minimizing fire-caused losses due to damaged cambium by re-routing the functions of fire-killed portions within weeks after a fire
  • reduced fire frequency (government policy of fire suppression) has favored more shade-tolerant hardwoods and contributed to the decline of oak dominance in Eastern forests
  • to regenerate E. oak forests, frequent prescribed burning is needed to compensate for decades of fire exclusion
• resistance to windthrow – strongly developed taproot and a network of deep, spreading laterals
• herbivory defense – tannins in leaves and acorns inhibit digestion in herbivores by interfering with the actions of enzymes involved with breaking down proteins
• wildlife:
  • white-tailed deer, elk, hares, and moose browse leaves and young seedlings
  • mice, chipmunks and squirrels eat acorns
  • acorns are important food source for bobwhite, red-headed woodpecker, blue jay, wild turkey (which can eat >200 acorns in one “meal”) and many other birds and waterfowl
  • sprouted acorns are eaten by deer, mice, and the northern bobwhite
  • tree branches provide cover, perching and nesting sites and nesting materials for birds and small animals, and denning sites for mammals