Plants erect, not colonial, sometimes suckering, 10-50 dm; twigs green, angular to terete, usually hairy in lines. Leaves usually deciduous; blade dark green, ovate to narrowly elliptic, 15-70 × 10-25 mm, subcoriaceous, margins sharply serrate or entire, surfaces glabrous or hairy abaxially. Flowers: calyx green, glabrous; corolla white to pink, ± cylindric, 5-12 mm; filaments usually ciliate. Berries dull black to blue, glaucous, 4-12 mm diam., glabrous. Seeds 10-20(-25), ca. 1.2 mm. 2n = 24, 48, 72. Flowering spring(-early summer). Open swamps, bogs, sandy margins of lakes, ponds, and streams, flatwoods, gray-birch scrub, pine barrens, mires, bay heads, upland ericaceous meadows, upland woods, ravines, mountain summits; 0-1600 m; B.C., N.B., N.S., Ont., Que.; Ala., Conn., Del., Fla., Ga., Ill., Ind., Ky., La., Maine, Md., Mass., Mich., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Vt., Va., Wash., W.Va., Wis.; introduced in Europe (Britain, The Netherlands), e Asia (Japan), Pacific Islands (New Zealand). Every morphological variant of the high-bush blueberry has been named formally at one time or another. At least 25 such taxa have been raised to specific rank; none is distinct throughout its putative range nor has the properties normally associated with biological species, including Vaccinium atrococcum and V. elliottii. See S. P. Vander Kloet (1980) for a complete list of synonyms. Feral populations readily become established wherever cultivars have been planted, e.g., Britain, British Columbia, Japan, Missouri, The Netherlands, New Zealand, Washington, and Wisconsin.
From Flora of Indiana (1940) by Charles C. Deam
This species is restricted to the lake area where it was formerly frequent to common over large areas. It grows in boggy and swampy places in tamarack bogs, marshes, and interdunal sloughs. Before the lake area was drained it covered hundreds of acres of swamp land but there now remain only a few small blueberry marshes.
The following varieties are of questionable value [with differences based upon ciliated leaf margins and leaf color]:
[Variety amoenum:] This form has been reported from Lake County by Hill and from Montgomery County by Grimes. I have seen the Grimes specimen, which is now in the herbarium of DePauw University, and it should be referred to Vaccinium corymbosum var. pallidum.
[Variety atrococcum:] I have specimens from Lagrange, La Porte, Kosciusko, Starke, and Steuben Counties which If refer to this variety.
[Variety pallidum:] This form has been reported from Indiana but since its range is given as Virginia to South Carolina, it is doubtful whether it occurs in Indiana. There is, however, a shrub mostly 3-5 feet high in the "knobs" of the unglaciated area that I place here for want of better determination. I do not believe that these plants belong to Vaccinium corymbosum but are, of themselves, a unit, which may belong to the Vaccinium pallidum of Small's "Flora of the Southeastern United States." Of the Indiana species, they seem to be nearest related to Vaccinium vacillans. There are probably two species or varieties in this complex. The leaves are mostly oval or obovate to elliptic, acute, acuminate, or somewhat obtuse, glabrous or more or less pubescent all over, the margins ciliolate-serrulate; fruit usually black, subglobose, sweet, and one form with glaucous fruit, about 8 mm wide and 9 mm long. It is usually associated with chestnut oak. The specimens in the DePauw University herbarium collected by Grimes on the "Devil's Backbone" in Montgomery County belong here. They were reported as Vaccinium coryrnbosum var. amoenum.
Crown-forming shrubs (0.5)1-3(-5) m; lvs ovate to narrowly elliptic, deciduous, 3-8 נ1.5-4 cm, variously serrulate or often entire, hairy (rarely glandular) or glabrous and sometimes glaucous; cor white or greenish-white to pink, cylindric to urceolate cylindric, 5-10 mm; fr blue-glaucous to black, 5-12 mm; 2n=24, 48, 72, ours mostly 48. Open swamps and bogs, or sometimes in upland woods or in old fields, from the coastal plain to the mt.-tops; Me. and N.S. to Fla., w. to Mich., n. Ill., Ky., Ark., e. Okla., and e. Tex. Apr.-July. (V. atrococcum; V. australe; V. caesariense; V. constablaei; V. marianum; V. simulatum; Cyanococcus atrococcus; C. margarettae; C. s.) Highly variable, not readily sorted into recognizable taxa. V. caesariense Mack., a diploid with glabrous, glaucous, entire lvs, glabrous or subglabrous twigs, and blue-glaucous fr, is ±distinguishable from the variable remainder of the group, diploid or often polyploid, with variously entire or serrulate, glabrous or hairy lvs and twigs, and blue or often black fr.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.