Federal and State Listed Species of Texas:
Hinckley's oak

Distribution

Current

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Distribution map of Hinckley's oak (Quercus hinckleyi).

Scientific Name
Quercus hinckleyi
Other Scientific Names
None
Other Common Names
chaparro
Status
Federally and State Threatened
Global Rank
G2
State Rank
S2

Global Location

Earth fruit is known from Anderson, Gregg, Harrison and Panola counties in Texas, and in the neighboring states of Arkansas, Louisiana, and Missouri.

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Description

Hinckley’s oak is an evergreen shrub (to 1 m tall), which forms thick stands with its interwoven, intricate branches. Although twigs and leaves emerge red, they mature to a light brown and blue-green, respectively. Twigs have microscopic, star-shaped hairs, and twigs and leaves are covered with a whitish, wax-like coating. Mostly round in outline, the leaves are 0.5-1.5 cm long and wide, leathery, waxy, and hairless. Leaf edges have four to six spine-tipped teeth. Clusters of male flowers hang downward from a sparsely hair-covered 3-5 mm long stalk while the female flowers occur singly almost directly on the stem. The saucer-shaped acorn caps are 1-3 mm tall and 10-15 mm wide, only enclosing the base of the nut. The egg-shaped nuts are 10-20 mm long and 8-12 mm wide, and hairless.

Hinckley’s oak twigs and leaves emerge red, but twigs change to a light brown and leaves to a blue-green. Leaf edges have four to six spine-tipped teeth. Clusters of male flowers hang downward from a stalk.

Credit: Mark Lockwood - Texas Parks & Wildlife Dept.

Hinckley’s oak leaves are covered with a whitish, wax-like coating. The saucer-shaped acorn caps only enclose the base of the egg-shaped nuts.

Credit: Jackie Poole - Texas Parks & Wildlife Dept.

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Similar Species

Hinckley’s oak can usually be identified by its shrubby stature, very small, round, hairless leaves, and the four to six spine-tipped leaf edges. However, Hinckley’s oak’s range overlaps with the more common pungent oak (Quercus pungens). Pungent oak is generally taller (1-2+ m), and has dense star-shaped hairs on the lower leaf surface. Also, pungent oak’s oval leaves are larger (1-4 cm long and 1-2 cm wide), and the leaf edges are wavy with spine-tipped lobes or sharp tooth-like projections.

Pungent oak has dense hairs on the lower surface of its oval leaves.

Credit: Roy Morey

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Floral Characters

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Leaf Characters

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Habitat

Hinckley’s oak occurs in Chihuahuan desert shrublands on rocky slopes at low to moderate elevations.

Habitat of Quercus hinckleyi (plants in foreground).

Credit: Jackie Poole - Texas Parks & Wildlife Dept.

Life Cycle Events

Flowering occurs in the spring. Acorns are produced every year and mature in August and September.

Survey Season

Hinckley’s oak can be recognized year-round.

Comments

Woodrats create large middens, or nests, from many found objects in their environment (plant materials, animal remains, and other debris). In the dry climate of the desert Southwest, these nests preserve the objects in them. Excavation of West Texas woodrat middens has revealed that Hinckley’s oak was much more common 15,000 years ago. When the area started to dry out around 11,000 years ago, Hinckley’s oak range contracted to the scattered, smaller areas it inhabits today (Van Devender et al. 1978).