12. Quercus shumardii Buckley (Shumard oak)
Quercus shumardii var. schneckii (Britton) Sarg.
Quercus shumardii var. stenocarpa Laughlin
Pl. 415 c, d;
Map 1850
Plants trees to
35 m tall. Bark medium to dark gray, divided into narrow persistent ridges, the
inner bark pinkish. Twigs 2.0–3.5 mm wide, yellowish brown, grayish brown, or
dark brown, glabrous. Buds 4–8 mm long, brown to grayish brown or sometimes
dark brown, glabrous. Petioles 25–72 mm long. Leaf blades 11–17 cm long, 8–18
cm wide, truncate or broadly obtuse at the base, divided (50–)60–90% of the
width, the lobes 3 or 4 per side, the largest lobes at or above the midpoint; well-developed
lobes 25–60 mm wide, obovate and broadened outward (usually strongly so),
rarely ovate, acutely angled or tapered apically, rarely rounded-obtuse, with
several teeth, 1 or 2 secondary lobes on the lower margin and 0 or 1 on the
upper margin, each with 5–12 bristles 2–5 mm long (the whole blade with 25–60
marginal bristles); the strongest secondary veins reaching the margin at the
tips of the lobes and ending in bristles, others reaching toward sinuses and
turning aside before reaching the margin; the upper surface glossy, glabrous,
the undersurface green, glabrous or rarely with inconspicuous, unbranched,
appressed hairs, smooth to the touch, the vein axils with prominent tufts of
7–15-rayed, stalked hairs. Acorn cups 5–14 mm long, 12–24 mm wide, covering
20–50% of the nut, saucer- or bowl-shaped, the inner surface smooth, glabrous
or with a few hairs near the nut scar, the outer surface with the scales mostly
distinctly convex-thickened at the base, sparsely pubescent. Nuts 14–27 mm
long, 11–19 mm wide, ovoid or almost cylindric, without concentric grooves
around the tip. April–May.
Scattered in the
southern 2/3 of the state (eastern U.S. west to Nebraska and Texas; Canada).
mesic to dry upland forests, savannas, edges of glades, tops of bluffs, banks
of streams and rivers, and rarely margins of fens.
Forms with the
acorn cup deeply bowl-shaped have been called var. schneckii. Steyermark
(1963) noted that in Missouri such plants tend to occupy sites at the dry end
of the ecological spectrum of the species. However, Hess and Stoynoff (1998)
noted that the type of var. schneckii originated from a bottomland site
in southern Illinois, and they could not distinguish trees at the type locality
of this segregate from typical var. shumardii. Similarly, Laughlin
(1969) segregated var. stenocarpa to distinguish large trees in Missouri
and Illinois having ellipsoid acorns with very shallow cups. Another variant
that most botanists currently treat as a separate species is Quercus
acerifolia (E.J. Palmer) Stoynoff & W.J. Hess (Q. shumardii var.
acerifolia E.J. Palmer), maple-leaved oak, which differs in its nearly
palmately compound leaves that are mostly wider than long. Although this taxon
currently is thought to be endemic to west-central Arkansas, some specimens of Q.
shumardii from southwestern Missouri come close to it in their leaf lobing
pattern and dimensions. Morphological variation within this species complex
requires further study before such variants can be recognized with confidence.
It seems likely that in the future new data from molecular or other sources
will result in a refinement of the taxonomy of Q. shumardii and its
variants. Potentially complicating the issue is the fact that hybrids with four
other oak species have been documented from Missouri.