Orobanche uniflora

Plants simple or few-branched basally, sometimes forked medially, 3.5–18(–25) cm (including pedicels), stem portion 1–5(–7) cm, slender, base not enlarged. Roots inconspicuous, slender or stout, unbranched or few-branched. Leaves relatively few, loosely imbricate or more remote, loosely ascending to spreading; blade oblong-lanceolate to awl-shaped, 2–10 mm, margins entire, often inrolled, apex acuminate, surfaces glabrous. Inflorescences of solitary flowers or fascicles of 2(–4) at stem or branch tips, white to cream, sometimes purple tinged, simple, glabrous; bracts loosely ascending and erect, oblanceolate to broadly ovate, obovate, rhombic, or awl-shaped, 5–12 mm, apex acute to acuminate, glabrous, rarely glandular-pubescent distally. Pedicels (8–)20–110(–170) mm, much longer than plant axis; bracteoles 0. Flowers: calyx white to straw colored or light yellow, or pale to dark, dull purple, sometimes brownish, ± radially symmetric, 4–12(–15) mm, divided into 5 subequal lobes, lobes slightly shorter than to 2 times as long as tube, ± triangular or subulate-triangular, sparsely to moderately glandular-pubescent; corolla (11–)15–30(–35) mm, tube white to purple, blue, or yellow, sometimes lighter proximally or with light or darker purple or blue veins, slightly to moderately constricted above ovary, ± bent forward, glandular-pubescent; palatal folds ± prominent, bright yellow, glandular- and/or eglandular-pubescent, sometimes glabrescent; lips white, yellow, purple, or blue, sometimes with light or darker purple or blue veins, abaxial lip slightly to moderately spreading, sometimes ± recurved distally, (1–)2–6(–9) mm, lobes oblong-obovate to nearly round, apex rounded to bluntly pointed or shallowly emarginate (sometimes with 2 notches), adaxial lip slightly to moderately spreading, sometimes recurved, 2–6(–9) mm, lobes broadly oblong-ovate to oblong-semiorbiculate, apex rounded, rarely bluntly pointed or shallowly emarginate; filaments glabrous, anthers included, glabrous or villous-tomentose. Capsules ovoid to oblong-ovoid, 4–8(–11) mm. Seeds 0.1–0.4 mm.

Distribution

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Alta., B.C., Man., N.B., N.S., Nfld. and Labr. (Nfld.), Ont., P.E.I., Que., Sask., Alaska, Ariz., Ark., Calif., Colo., Conn., D.C., Del., Fla., Idaho, Ill., Ind., Iowa, Kans., Ky., Maine, Mass., Md., Mich., Minn., Miss., Mo., Mont., N.C., N.Dak., N.H., N.J., N.Mex., N.Y., Nebr., Nev., Ohio, Okla., Oreg., Pa., R.I., S.C., Tenn., Tex., Utah, Va., Vt., W.Va., Wash., Wis., Wyo., Mexico.

Discussion

Subspecies 2 (2 in the flora).

Orobanche uniflora forms a polymorphic complex that requires more detailed study. The detection of broad-scale patterns of morphological variation is confounded by the differentiation among local races. D. M. Achey (1933) recognized five varieties, and K. C. Watson (1975), in her unpublished thesis, revised the classification to three subspecies. The present treatment, which accepts only the two major infraspecific variants as subspecies, should be considered highly tentative.

Selected References

None.

Lower Taxa

Orobanche uniflora subsp. occidentalis, Orobanche uniflora subsp. uniflora

Key

1	Calyx lobes slightly shorter than to only slightly longer than tubes, narrowly to broadly lanceolate-triangular; corollas white to pale yellow, sometimes pale purplish tinged and/or with light purple veins.	Orobanche uniflora subsp. uniflora
1	Calyx lobes ca. 2 times as long as tubes, subulate-triangular; corollas purple to blue (often with a white throat), yellow, or white, often with darker purple or blue veins.	Orobanche uniflora subsp. occidentalis