Perennial herb 20 - 50 cm tall Leaves: alternate, elongate, and pinnately compound. The lowermost leaves have long stalks, but the upper leaves are sometimes stalkless. Inflorescence: ascending, loose and open, minutely hairy, with slender branches ending in few-flowered, branching clusters. Flowers: deep blue, 1.2 - 1.6 cm long, radially symmetric, bell-shaped, and on stalks at least 5 - 6 mm long (at least the same length as the sepals). Sepals: five, minutely hairy, only 5 - 6 mm long overall, but fused for about half their length, then separating into broadly triangular lobes. Petals: five, but fused for up to half their length, then separating into non-toothed, oval to inversely egg-shaped lobes. Stamens: five, filaments declined and hairy at the base, attached at the top of the petal tube, but not extending beyond the petal lobes. Pistil: with a single, three-chambered, superior ovary; and three, partially fused styles, which are shorter than, or about the same length as the petals, and end in three, linear stigmas. Fruit: a short-stalked, three-chambered capsule with one to ten seeds per chamber. When wet, the seeds sometimes become sticky and gelatinous (mucilaginous). Leaflets: seven to seventeen, each 2 - 4 cm long, oblong, elliptic, or egg-shaped, and often less than twice as long as broad. Stems: several or solitary, loosely clustered or tufted, erect or low, but open branched, slender, and usually hairless.
Similar species: This is the only species of Polemonium in the Chicago Region, and as described above, we only have the typical variety. However, in southern Ohio and nearby areas of Kentucky there is P. reptans var. villosum, which can be differentiated by its smaller flowers (usually under 1.3 cm long), and the densely, long, glandular-hairy stem and inflorescence. A more western species, P. occidentale, only occurs as close as northern Minnesota and differs by having longer and more narrow inflorescences, flower stalks shorter than the sepals, and a later flowering time (summer, not spring). In the Appalachian area there is P. van-bruntiae, which differs by having the stamens extending far beyond the petals. A third species, P. caeruleum, is native to Europe and occasionally escapes cultivation. It can be distinguished by its clustered stems, stalkless fruit, a greater number of leaflets on the lower leaves (at least nineteen), the leaflets being more lance-elliptic, and two to four times longer than wide.
Flowering: mid-April to early June
Habitat and ecology: Frequent in somewhat mesic, high-quality woods, especially in regularly burned oak woods. It is also occasionally found in calcareous fens and even prairies.
Occurence in the Chicago region: native
Author: The Field Museum
From Flora of Indiana (1940) by Charles C. Deam
Our manuals call this species Greek Valerian. Frequent to common in deep humus throughout the state, although there are no specimens from Lagrange or Steuben Counties. It is more abundant when associated with beech and sugar maple and white oak and red oak. It is rarely found in springy places but sometimes it is found in low, flat woods in the southwestern part of the state. It is rarely found in the open along roadsides and railroads, although when introduced into cultivation it thrives in the open. Two old pioneers told me that the root was a diuretic and a specific for kidney disorders.
Stems loosely clustered or solitary, slender, 2-5 dm, erect to diffuse, branched above; basal lvs long-petioled, cauline less so or the upper sessile; lfls oblanceolate to oblong or elliptic, 2-4(-7) cm, those of the principal lvs 7-17; infl few-fld, loose and open, the pedicels nearly as long to longer than the cal; cal 5-6 mm, the broadly triangular lobes nearly as long as the tube; cor campanulate, lobed to about the middle, the lobes entire; stamens shorter than the cor; 2n=18. Rich, moist woods; N.Y. to Minn., s. to Va., Ala., and e. Okla., most abundant w. of the mts. Apr.-June. (P. longii, a pathological form) Var. reptans, with nearly the range of the sp., has the infl and cal minutely puberulent and the stem usually glabrous; the cor is mostly 12-16 mm. Var. villosum E. L. Braun, local in s. O. and adj. Ky., and largely replacing var. reptans there, has the infl densely glandular- villous, the stem usually glandular-villous as well, and the cor mostly 8-12(-13) mm.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.