Key to Wisconsin Lithospermum

• 1a.Corolla cylindrical, the lobes acute, inflexed to barely spreading; styles long-exserted 2

• 1b.Corolla funnelform or salverform, the lobes spreading, rounded; styles included 3

• 2a.Nutlets constricted just above the base to form a collar; plants densely and coarsely hirsute with spreading to ascending and also appressed whitish hairs (these becoming yellowish in the inflorescence), the longest ones near midstem almost always exceeding 2.3 mm; abaxial leaf pubescence between the veins clearly of two kinds, with a few long and ascending and most short and appressed L. parviflorum

• 2b.Nutlets rounded at the base, not constricted; plants canescent, both densely hirtellous with appressed hairs and finely hirsute with ascending to spreading hairs, these pure white (occasionally slightly yellowish), the longest ones near midstem never exceeding 2.2 mm; abaxial leaf pubescence between the veins typically softer, much denseer, and more uniform, mostly subascending to erect L. occidentale

• 3a.Corollas light to deep yellow, the limb 9–22 mm wide, much exceeding the calyx; leaf blades linear to narrowly oblong or narrowly lanceolate, lacking secondary veins; plants with a terminal inflorescence (elongating later in the season which makes the flowers appear axillary) 4

• 3b.Corollas white to pale yellow or greenish, the limb less than 8 mm wide, about as long as the calyx lobes; leaf blades lanceolate to narrowly ovate, with pronounced secondary veins, plants with flowers appearing mostly axillary 6

• 4a.Corolla tube (unexpanded portion) 20–35 (–40) mm long, the lobes distinctly fringed or erose; leaves narrowly linear, usually less than 4 mm wide (rarely to 5 or 6 mm); stem pubescence closely appressed L. incisum

• 4b.Corolla tube 5–14 mm long, the lobes entire; leaves usually wider than 5 mm (sometimes as narrow as 4 mm in early season plants); stem pubescence partly or all spreading 5

• 5a.Pubescence of leaves, stems, and bracts soft, usually not pustulate-based; calyx lobes 2–4 mm long (to 7 mm in fruit) L. canescens

• 5b.Pubescence stiff and rough, of slightly pustulate-based hairs; calyx lobes (5–) 6–10 (–14) mm long L. caroliniense

• 6a.Largest leaves or bracts 0.5–1.6 (–2) cm wide, lanceolate L. officinale

• 6b.Largest leaves or bracts 2–4 cm wide, narrowly ovate to ovate L. latifolium