Herbs. Stems annual, erect, unbranched, 0.5-1 m, herbaceous; prickles absent. Leaves numerous, evenly distributed, larger distally; petiole thin, equaling or longer than blade; tendrils distal, few, short; blade narrowly ovate, pubescent and not glaucous abaxially, base rounded to truncate, margins convex, apex acute to acuminate. Umbels 3-10, axillary to leaves and bracts, 10-50-flowered, semiglobose; proximalmost peduncle longer than distalmost. Flowers: tepals 3.5-4.5 mm; anthers usually shorter than filaments; ovules (1-)2 per locule. Berries blue to black, globose. 2n = 26. Flowering May--Jun. Roadside thickets, woods; 150--600 m; Ont.; Ill., Ind., Iowa, Mich., Minn., Mo., Ohio, Wis. Smilax illinoensis is intermediate between S. ecirrhata and S. lasioneura.
Perennial herb 0.5 - 1 m tall Stem: erect, unbranched, lacking prickles. Leaves: alternate, numerous, thin-stalked, narrow egg-shaped with a rounded to squared base and a pointed tip, margins convex, hairy beneath. Flowers: either male or female, found on separate plants (dioecious), borne on an inflorescence with branches radiating from a common point (umbel). The few umbels are borne axillary to the leaves and bracts, each being semi-spherical and having ten to 50 flowers with six tepals 3.5 - 4.5 mm long. Fruit: a spherical blue to black berry. Tendrils: few, borne in upper leaf axils, short.
Similar species: Smilax ecirrhata, Smilax illinoensis, Smilax herbacea, Smilax lasioneura, and Smilax pulverulenta are herbs without prickles. Smilax herbacea, S. lasioneura, and S. pulverulenta climb to more than 1 m and have many tendrils and umbels. Smilax ecirrhata differs by typically having broader leaves and fewer than 25-flowered umbels that are axillary to the bracts.
Habitat and ecology: Occasional in thickets, often near roadsides.
Occurence in the Chicago region: native
Etymology: Smilax is the ancient Greek name of an evergreen oak. Illinoensis means "from Illinois."
Found occasionally throughout most of the range of S. ecirrhata, may reflect hybridization with S. herbacea var. lasioneura. It is erect like S. ecirrhata, with the peduncles mainly below the foliage-lvs, but it averages taller, with more numerous lvs (many of them tendriliferous), and has more numerous (mostly more than 25) fls on longer peduncles.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.