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..2 Flowers yellow; bracteoles 2 on the pedicel; pedicels 1-3 mm long, shorter than the calyx; glandular hairs dense on the leaves and on the stems (and extending on the stems to the base)
....3 Flowers white or yellow; leaves gradually reduced in size upwards
....3 Flowers purple; leaves abruptly reduced in size in the upper half of the stem
......4 Inflorescence generally simple (sometimes with 1-several small branches from near the inflorescence base), dense and spike-like (at least initially); leaves moderately to densely tomentose above (or glabrescent in V. nigrum ssp. nigrum); upper 3 filaments bearing white hairs (or all 5 bearing violet hairs in V. nigrum ssp. nigrum).
........5 Basal and lower stem leaves with blades basally cordate to nearly truncate; leaves sparsely tomentose to glabrate, quickly glabrescent abaxially, sometimes glabrate on both surfaces, thinly tomentose on abaxial leaf surface but not completely obscuring epidermis; all filaments villous with purple to violet hairs
..........6 Middle to upper stem leaves sessile to auriculate-clasping, slightly or not at all decurrent on the stem; stigma patulate, decurrent on the style; corollas white or yellow
............ 7 Corollas 30-55 mm in diameter; pellucid glands of the corolla absent or very few; anthers orange; pedicels adnate to the rachis or often free
............ 7 Corollas 14-20 (-30) mm in diameter, pellucid glands of the corolla numerous; anthers yellow; pedicels all or nearly all adnate to the rachis
............ ..8 Basal leaves lobed; upper leaf surface loosely to densely tomentose; filaments bearing violet hairs
............ ....9 Mid-stem leaves sessile to subsessile; filaments villous with white to yellow hairs
............ ....9 Mid-stem leaves distinctly petiolate, filaments villous with purple to violet hairs