Trees to 40m; trunk to 1.2m diam., straight; crown rounded to conic. Bark red-brown, scaly-plated, plates with evident resin pockets. Branches spreading-ascending; 2-year-old branchlets slender (ca. 5mm or less), greenish brown to red-brown, often glaucous, aging red-brown to gray, roughened and cracking below leafy portion. Buds ovoid to cylindric, red-brown, 0.5--0.7(--1)cm, resinous. Leaves 2(--3) per fascicle, spreading-ascending, persistent 3--5 years, (5--)7--11(--13)cm ´ ca. 1mm, straight, slightly twisted, gray- to yellow-green, all surfaces with fine stomatal lines, margins finely serrulate, apex abruptly acute; sheath 0.5--1(--1.5)cm, base persistent. Pollen cones cylindric, 15--20mm, yellow- to pale purple-green. Seed cones maturing in 2 years, semipersistent, solitary or clustered, spreading, symmetric, lanceoloid or narrowly ovoid before opening, ovoid-conic when open, 4--6(--7)cm, red-brown, aging gray, nearly sessile or on stalks to 1cm, scales lacking contrasting dark border on adaxial surfaces distally; umbo central, with elongate to short, stout, sharp prickle. Seeds ellipsoid; body ca. 6mm, gray to nearly black; wing 12--16mm. 2 n =24. Uplands, dry forests; 200--610m; Ala., Ark., Del., Fla., Ga., Ill., Ky., La., Md., Miss., Mo., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W.Va. Although Pinus echinata is highly valued for timber and pulpwood, it is afflicted by root rot. It hybridizes with P . taeda , the pine most commonly associated with it.
Tree to 35 m; bark at first scaly and nearly black, later becoming red-brown and scaly-plated; twigs pale and glaucous; winter buds less than 1 cm, red-brown to gray- brown, not strongly resinous; lvs in 2's or 3's, persistent 2-4 years, soft, dark green, 7-12 cm נca 1 mm; cones divergent, ovoid to ovoid-conic, 4-6 cm, opening at maturity but persisting several years; apophysis somewhat elevated, the umbo low-pyramidal, with a stout or slender, recurved or spreading spine 1-2 mm; seeds ca 2 cm. Dry, sandy or rocky soil; s. N.Y. to n. Fla., w. to s. O., s. Mo., e. Okla., and e. Tex.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.