Lower leaves crowded to form a rosette and their opposite arrangement obscured § Euplagiobothrys
Racemes bractless; nutlets 2.5–3 mm. long , with an excavated annulate carunculate scar; plant 1.5–5 dm. tall, dyestained only on root and on midribs and bases of lower leaves ...... P. fulvus
Racemes bracted; nutlets 1-2 mm. long, with solid scar; plant 0.5–2 dm. tall, dye-stained throughout
Plant prostrate or spreading; nutlets 1.3–2 mm. long, with low rounded ridges; Argentina and Chile ...... P. verrucosus
Plant erect or strictly ascending; nutlets 1–1.5 mm. long, with sharp well developed ridges or papillae; Crule and Peru ...................................... P. tinctorius = P. myosotoides
Lower leaves not crowded to form a rosette, loose, with the lowermost evidently opposite
Ventral keel drawn out below the middle into a short stipe bearing the areola. § Echidiocarya ...... P. collinus
Ventral keel not at all drawn out into a stipe, the areola sessile. § Allocarya
Corolla much surpassed by calyx; plant ca. 5 cm. tall; leaves filiform1 0.5-2 cm. long, 1 mm. broad; calyx cylindrical, subse sile, strict, 2.7-3 mm. long;
a very poorly understood species of central Chile ...... P. armeriifolius
Corolla at length equalling and usually clearly surpassing the calyx
Plant perennial, mostly of high altitudes
Plants densely strigose; stems ascending; southern Chile.
Stems with only a single pair of opposite leaves; leaves 2–5 cm. long, 1–2.5 mm. broad ...... P. germaini
Stems with 4-6 pairs of opposite leaves; leaves 1–2.5 cm. long, 0.6-1 mm. broad ...... P. foliosus
Plants sparsely villous or glabrescent; stems prostrate or long-trailing; northern Argentina to Colombia.
Style very much surpassing the mature fruit; flowers in axils of cauline leaves or in subacaulescent forms from a leafy tuft and seemingly scapose;
corolla 4-6 mm. broad; pedicels 3–6 mm. long, slender; Lake Titicaca Region ...... P. kunthii
Style short, shorter than or at most reaching to the tips of the nutlets
Flowers racemose, in axils of alternately disposed bract; Peru, Bolivia and northern Argentina.
Tips of calyx-lobes darkly tawny; racemes usually elongate and loose; foliage very sparsely strigose or glabrescent ...... P. humilis
Tips of calyx-lobes at most pale straw -colored; racemes usually glomerate; foliage cinerescent, hispid-villous ...... P. congestus
Flowers solitary in the axil of the opposite cauline leaves; Ecuador and Colombia
Corolla 2.5-3.3 mm. broad; mature calyx with short obscure pedicels 0.3-0.9 mm. long; leaves narrowly oblance-linear, 0. 1.5 cm. long, 0.8-1.1 mm. broad ...... P. pygmaeus
Corolla 4-6 mm. broad; mature calyx with evident pedicels 1-1.5 mm. long; leaves narrowly oblanceolate or linear-oblanceolate, 1-2.5 cm. long, 1.5-3 mm. broad ...... P. linifolius
Plant annual, mostly from low altitudes
Corolla inconspicuous or small, 1–3 mm. broad.
Nutlets not rugose, merely tuberculate or papillate; scar large, concave or somewhat excavated; Peru ...... P. macbridei
Nutlets always somewhat transversely rugose, frequently also more or less tuberculate or papillate; Chile.
Nutlets with an excavated or decidedly concave scar, reticulate-rugose, all somewhat tuberculate or papillate or subulate-appendaged or commonly only the more or less
heteromorphous axial one so, appendages frequently glochidiate ...... P. procumbems
Nutlets with a solid scar, not papillate or subulate-appendaged, definitely homomorphous; appendages never glochidiate.
Nutlets narrowly reticulate-rugose, ovate, ca. 1 mm. long ...... P. polycaulis
Nutlets broadly transverse-rugose, usually narrowly ovate, 1.5-2.3 mm. long
Nutlets decidedly compressed, with a convex or very broadly (obtuse-)angled anterior face ...... P. calandrinioides
Nutlets weakly compressed, with a prominently (right-)angled anterior face ...... P. oppositifolius
Corolla evident to large, (3–)4–6 mm. broad
Nutlets sparsely but prominently papillate, transverse rugae obscure or none ...... P. pulchellus
Nutlets reticulate-rugose
Reticulate ridging of nutlets prominent and narrow ...... P. uliginosus
Reticulate ridging of nutlets low and broad
Lower pedicels elongating, very slender, 4-8 mm. long ...... P. pedicellaris
Lower pedicels, 0.5-3 mm. long
Herbage sparsely and inconspicuously strigose; style surpassing the nutlets ...... P. corymbosus
Herbage densely strigose; style reaching to the tips of the outlets ...... P. pratensis
Note: Not including: P. gracilis.
