Flora of the Southeastern United States
2022 Edition

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Key to Verbena

Click the number at the start of a key lead to highlight both that lead and its corresponding lead. Click again to show only the two highlighted leads. Click a third time to return to the full key with the selected leads still highlighted.

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 aliens 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; [aliens 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 tightly adhering in fruit, appearing as one; calyx lobes curved inward in fruit; corolla pink to pinkish lavender; [section Verbena, series Connaticarpae]
........................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