1 Spikes short and stout, the flowers or fruits overlapping and completely obscuring all of the rachis (except in V. montevidensis, the fruits spaced toward the base of the spike); [weedy exotics usually of disturbed areas]

  2 Plant procumbent or decumbent; leaves pinnately lobed or dissected; [section Verbena, series Bracteatae]

  2 Plant erect; leaves coarsely serrate.

    3 Leaves basally attenuate to short-petiolate; corolla tubes 2.5-5 mm long.

      4 Central spikes sessile to subsessile, spikes compact, 3-5 mm wide, fruits remaining densely overlapping at maturity; [section Verbenaca, series Pachystachyae]

      4 Central spikes pedunculate, spikes loose, 2-3 mm wide, with fruits becoming remote at least in the proximal portion at maturity; [section Verbenaca, series Litorales]

    3 Leaves basally clasping to subclasping; corolla tubes 2.5-9 (-11) mm long; [section Verbenaca, series Pachystachyae].

        5 Corolla tube (5-) 6.5-9 (-11) mm long

        5 Corolla tube 2.5-6 (-7) mm long.

          6 Corolla tube 4-6 (-7) mm, 1.5-2 mm longer than the calyx; distal stems, peduncles, and calyces stipitate-glandular; spikes 8-30 mm long in fruit; floral bracts 2.1-2.8 mm; nutlets 1.5-1.9 mm; basal and midstem leaves oblong-lanceolate to oblong-oblanceolate

          6 Corolla tube 2.5-4 mm, 0-0.5 mm longer than the calyx; stems, peduncles, and calyces eglandular; spikes (6-) 35-55 mm long in fruit; floral bracts 3-4 mm; nutlets 1-1.2 (-1.4) mm; basal and midstem leaves ovate to ovate-lanceolate, oblong-elliptic, or obovate

1 Spikes elongate, the flowers or fruits well-spaced and not obscuring the rachis; [exotics and natives, collectively of a range of habitats].

             7 Leaves mostly lobed or dissected.

               8 Plants much branched at base, stems decumbent to ascending; leaves 1-5 cm long; [section Verbena, series Tricesimae]

               8 Plants little branched, stems erect; leaves 3-12 cm long.

                 9 Bractlets about as long as the calyx; [AL westward]; [section Verbena, series Candelabrae]

                 9 Bractlets about ½ as long as the calyx; [collectively widespread].

                   10 Basal and lower cauline leaves persistent, relatively thick, large and spatulate, margins revolute, cauline leaves quickly reduced in size distally and becoming linear-entire; rachis and calyces eglandular; [section Verbena, series Haleae]

                   10 Basal leaves usually deciduous, relatively thin, margins not revolute, cauline leaves relatively even-sized upward or largest near midstem; rachis and calyces stipitate-glandular, sometimes sparsely so; [section Verbena, series Verbena]

             7 Leaves not lobed or dissected, or some of the leaves lower on the stem 3-lobed.

                     11 Stem leaves sessile or subsessile, cuneate to base.

                       12 Leaves linear to narrowly oblancolate, < 1.5 cm wide, > 6× as long as wide; [section Verbena, series Simplices]

                       12 Leaves ovate, 2-4 cm wide, < 4× as long as wide

                          13 Mericarps separate in fruit; calyx lobes erect to divergent in fruit; corolla blue to violet; [section Verbena, series Candelabrae]

                     11 Stem leaves with well-developed petioles.

                            14 Flowers and fruits distinctly overlapping in the upper part of the spikes; [section Verbena, series Candelabrae]

                            14 Flowers and fruits well-spaced throughout the inflorescence; [section Verbena, series Leptostachyae].

                              15 Upper leaf surfaces densely scabrous or hispidulous to hispid or hispid-hirsute; calyx lobes triangular, connivent; corollas mostly pinkish to bluish, lavender, or purple; nutlet outer surfaces deeply ridged and grooved, often with prominent cross-ridges, commisural faces consistently densely silver-white minutely papillate-bullate; fibrous-rooted

                              15 Upper leaf surfaces hirsutulous to hirsute or strigose-hirsute; calyx lobes deltate-subulate, not connivent or subconnivent; corollas white, rarely pinkish; nutlet outer surfaces smooth to longitudinally ridged, sometimes with cross-ridges distally, commisural faces smooth or rarely with slight development of minutely bullate ornamentation; taprooted