Perennial, erect to suberect herb up to 50 cm tall. Stem generally solitary flaccid branched, with ascending branches, sparsely hairy with short appressed hairs Middle lower cauline leaves similar but larger, uppermost ones gradually reduced size. Inflorescence ebracteate, in flower scorpiod and compact, later elongating a lax, bearing flowers at regular intervals of 5-12 mm. Pedicels short in flower longer than calyx length, becoming ± horizontal and up to 10 mm in fruit. c. 2 mm long, c. ½ divided into ± obtuse lobes, up to 4 mm In fruit, sparsely with appressed hairs. Corolla blue; tube about calyx length, limb ± 3.5mm lobes ± ovate, spreading. Style shorter than calyx. Nutlets ovate; 1.5 x 1 mm, shiny, straw brown with a narrow margin, areola 0.5 mm broad.
Herbs perennial, with dense fibrous adventitious roots. Stems unbranched, sometimes branched, 15-50(-70) cm tall, sparsely strigose. Lower stem leaves petiolate, oblong to oblanceolate, 2-3 cm × 3-8 mm, sparsely strigose, base attenuate, margin entire, apex obtuse; upper stem leaves sessile, oblanceolate to linear-lanceolate, 3-7 cm × 5-13 mm. Inflorescences elongated after anthesis, to 10-20 cm in fruit, ebracteate, or lower several flowers from axils of linear bracts. Pedicel divaricate, 6-8 mm in fruit, usually longer than calyx. Calyx campanulate, cuneate at base, 5-lobed nearly to middle, ca. 2 mm, to 3-4 mm in fruit; lobes triangular, stiff, sparsely strigose outside, apex obtuse. Corolla light blue, 2-3 mm; tube ca. as long as calyx; throat yellow, with 5 appendages; limb 3-4 mm wide; lobes divaricate, ovate, ca. 1.5 mm. Anthers elliptic, ca. 0.6 mm, upper appendages rounded, ca. 3 × as long as anthers. Nutlets dark brown, ovoid, 1.5-2 mm, smooth, narrowly marginate above, apex obtuse. 2n = 22, 44, 48, 86, 88.
Lehmann; M. scorpioides
Linnaeus subsp. caespitosa
(C. F. Schultz) Hermann; M. uliginosa