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Northern Pin Oak (Hill's Oak)
Leaves are alternate, simple, lobed. Lobes have pointed tips. Fruit is an acorn.
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The northern pin oak is also called Hills oak, yellow oak, and jack oak. It
is similar to the red oak but does not get as large and is heavier
branched. The northern pin oak can be found in northeastern Iowa on moist,
sandy soils and clay upland.
The leaf lobes are bristle tipped, with lobe sinuses reaching almost toleaf mid-vein. The leaves are leathery in texture, dark shiny green above. The twigs are bright reddish brown to dark gray-brown.
Hardiness: Varies with the species of oak tree, ranging from zone 3 to zone 9.
Growth Rate: Slow to Moderate
Mature Shape: Broad, rounded
Height: Varies with species. Often maturing between 50 to 75 feet tall. Capable of growing upwards of 100 feet.
Width: 40 to 70 feet; varies with species
Site Requirements: Best growth in moist, well-drained soils. Adaptable to adverse soil conditions.
Flowering Dates: March - May
Seed Dispersal Dates: Late August - Early December
Seed Bearing Age: 20 years
Seed Bearing Frequency: Abundant crops every 2-3 years
Seed Stratification: Prechill for 2-3 months at 34°F to 40°F
The acorn is oval with the cap covering almost one-half. The edge of the cup is not deeply fringed.
The tree has a pale yellow, thin underbark. The outer bark is rather smooth, with shallow, connected fissures. It is dark brown near the base of tree to gray brown above.