Flora of the Southeastern United States
2022 Edition

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Key to Lobelia

1 Corolla bright red (faded in dried specimens) or very rarely white, 30-45 mm long; filament-tube (17-) 19-33 (-37) mm long
..2 Anther tubes (4.0-) 4.5-5.5 mm long; filament tubes (24-) 28-30 (-33) mm long; lower stem leaves petiolate; leaf blades mostly 3-5× as long as wide, usually coarsely toothed; [widespread in our area]
..2 Anther tubes 3.5-4.5 (-5.0) mm long; filament tubes (17-) 22-32 (-37) mm long; lower stem leaves sessile (to subsessile); leaf blades mostly 6-8× as long as wide, entire to prominently toothed; [of w. MO, e. OK, and c. TX westwards and southwards]
1 Corolla blue, purple, or white, 10-33 mm long; filament-tube 2-15 mm long.
....3 Larger leaves in a basal rosette, linear to linear-oblanceolate; [of wetlands, often growing in shallow to deeper water].
......4 Leaves fleshy, tubular, 2-9 cm long; [approaching our area from the north in NJ and PA, in permanently or semi-permanently ponded wetlands]
......4 Leaves flat, 2-30 cm long; [of the Southeastern Coastal Plain, from GA (or NC?) south to FL and west to LA, in seasonally saturated to ponded wetlands].
........5 Sinuses of calyx segments with small auricles (best seen on new flowers, often lost on old flowers and fruits); pedicels with very small bracteoles at the base (near the slender, leaf-like bract); corolla (12-) avg. 15-16 (-20) mm long; filament tube (6-) 7-9 (-11) mm long; corolla tube not fenestrate (lacking lateral slits, but older flowers may be torn); larger leaves 10-30 cm long; plants (5-) 8-10 (-15) dm tall
........5 Sinuses of calyx segments not auriculate; pedicels lacking bracteoles; corolla (10-) avg. 12-13 (-16) mm long; filament tube 3-4.5 mm long; corolla tube fenestrate (with lateral slits near the base between the calyx lobes); larger leaves 5-15 cm long; plants (4-) 5-6 (-13) dm tall
....3 Larger leaves cauline; [collectively widespread and in a range of habitats].
..........6 Plants mat-forming, the leaves basally-disposed but some stems trailing to decumbent, rooting at the nodes.
............ 7 Leaves lanceolate, sessile or subsessile; [of tidal rivers, lawns, and disturbed areas in s. NJ and adjacent PA]
............ 7 Leaves orbicular, obviously petiolate; [of n. FL southward]
..........6 Plants not mat-forming, stem leaves well-developed, stems normally erect and not rotting at the nodes.
............ ..8 Flowers smaller, 8-14 mm long (measured from base of calyx); filament tube smaller, 2.5-5 mm long; corolla usually not fenestrate (except sometimes in L. flaccidifolia).
............ ....9 Stem leaves very narrow, most less than 5 mm wide (lowest leaves may be broader).
............ ......10 Leaves subulate-filiform (narrowly linear), < 1 mm wide (leaves often deciduous); calyx glabrous; pedicels lacking bracteoles (but bracts present); stems often spongy-thickened toward the base; rhizomes present (the plants therefore forming clones, though the stems often spaced as much as a meter apart)
............ ......10 Leaves linear to linear-oblanceolate, 1-4 mm wide; calyx glabrous or pubescent; pedicel with bracteoles (as well as larger bract); stems not spongy-thickened; rhizomes absent.
............ ........11 Bracteoles borne near the middle of the pedicel; [wetlands from WV and PA northwards]
............ ........11 Bracteoles borne at the base of the pedicel; [collectively widespread in our area].
............ ..........12 Lower lip of corolla pubescent inside at the base near throat; pedicels and calyx often strongly antrorsely scabrid (with sharp upward-pointing hairs), rarely almost glabrous (but usually have a few antrorse hairs, especially on the pedicels); hypanthium oval to oblong in fruit; basal leaves linear
............ ..........12 Lower lip of the corolla glabrous; pedicels and calyx glabrous or pubescent with scattered straight hairs (they are spreading and often tooth-like with slightly broader bases); hypanthium short-hemispheric in fruit; basal leaves (when present) spatulate
............ ....9 Stem leaves broader, the largest more than 10 mm wide.
............ ............ 13 Lower leaves with distinct petioles; leaf bases truncate, rounded or subcordate; [FL and s. GA].
............ ............ ..14 Blades of lower leaves orbicular with entire to shallowly crenate margins; lower stems trailing, forming mats and usually rooting at the nodes (upper stems erect)
............ ............ ..14 Blades of lower leaves ovate with deeply crenate to incised-dentate margins; lower and upper stems erect
............ ............ 13 Lower leaves sessile or with a short petiole; leaf base narrowed, not truncate, rounded or subcordate; [collectively widespread].
............ ............ ....15 Stems long hirsute; fruiting capsules strongly inflated; lower flowers with ovate-leafy bracts; inflorescence usually much branched
............ ............ ....15 Stems glabrous or short-pubescent (base sometimes densely pubescent); fruiting capsules not inflated; flowers with smaller bracts; inflorescence branched or unbranched.
............ ............ ......16 Bracteoles conspicuous (somewhat foliaceous) and borne just below the middle of the pedicel (well above larger bract); calyx lobes toothed (some segments may be remotely toothed); flowers 14-20 mm long (measured from base of calyx)
............ ............ ......16 Bracteoles inconspicuous and borne at the base of the pedicel (adjacent to larger bract); calyx lobes mostly entire, rarely with a few teeth, though sometimes ciliate (ignore the leafy bract at the base of pedicel); flowers <15 mm long.
............ ............ ........17 Upper stem leaves oblong or obovate with narrowed bases; leaf margins often entire with tiny glandular teeth or occasionally undulate, crenulate to shallowly dentate; base of stem usually densely puberulent; plants rarely branched (if branched, then from lower two nodes, unless injured or late in season after main inflorescence has fruited); inflorescence spike-like with flowers 7-12 mm long that are borne on all sides; flowering mostly Jun-Aug
............ ............ ........17 Upper stem leaves short-ovate with broad, rounded bases (often partially clasping stem); leaf margins usually irregularly toothed with rounded teeth; plants often branched from lower and upper nodes (occasionally unbranched); inflorescence a raceme with flowers 10-15 mm long that are often borne partly on one side (partially secund); flowering mostly May-Jun.
............ ............ ..........18 Calyx lobes ciliate-margined with thick, sharp hairs (at least near apex); sinuses of calyx with auricles; [chalk prairies and other open areas on the Coastal Plain of e. AL west to TX]
............ ............ ..........18 Calyx lobes with glabrous margins; sinuses of calyx lacking auricles; [limestone glades on the Interior Low Plateau of TN and KY]
............ ..8 Flowers relatively large, the corolla (including the hypanthium) 18-33 mm long, fenestrate (with a slit or window on each side of the tube near the base) (or often not fenestrate in L. flaccidifolia).
............ ............ ............ 19 Leaves mostly < 3 cm long and very numerous, usually > 20 (leaves also < 7 mm wide); leaf margins prominently denticulate and apex rounded; sinuses of calyx with distinct auricles that overlap and often completely cover the calyx tube (hypanthium); calyx lobes pectinately toothed
............ ............ ............ 19 Leaves 4-15 cm and not as numerous, usually < 20; leaf margins variously toothed or entire and tips acute or rounded; sinuses of calyx with or without auricles; calyx lobes toothed or entire.
............ ............ ............ ..20 Stem leaves linear, lanceolate or oblanceolate (< 1.5 cm wide); lower lip of corolla either densely pubescent (on the upper portion near the opening of throat) or glabrous (glabrescent in the tube) (in L. species 1); calyx segments usually toothed (occasionally entire).
............ ............ ............ ....21 Pedicel with two conspicuous bracteoles borne above the base of pedicel (they are linear, somewhat foliaceous, and have acute tips); calyx tube short-pubescent or glabrous (pedicel short-pubescent or glabrous); corolla tube usually not fenestrate (lacking lateral slits); lower leaves usually < 7 mm long, with blunt or acute tips; upper stem leaves usually not strongly denticulate (but gland-tipped teeth are usually present); internodes not geniculate or only slightly so; plants often drying a lighter green
............ ............ ............ ....21 Pedicel with inconspicuous bracteoles borne at base and often hidden by bract (bracteoles are oval to oblong with blunt tips and look similar to glandular teeth of bract, except a little smaller); calyx tube either pustular (with wart-like bumps), long-hirsute, or glabrous (the pedicel short to long hirsute or glabrous); corolla tube fenestrate; lower leaves often > 7 mm long, often with sharp tips (but not always); upper stem leaves prominently denticulate (margins with numerous sharp, gland-tipped teeth); internodes often geniculate (zigzag); plants often drying darker.
............ ............ ............ ......22 Corolla lip densely pubescent basally, corolla tube relatively densely pubescent within; corolla 19-27 (-29) mm long; [middle and outer Coastal Plain, mostly in wet savannas, flatwoods, pitcher-plant bogs]
............ ............ ............ ......22 Corolla lip glabrous basally, corolla tube glabrate within; corolla 17-23 mm long; [NC-SC Sandhills region, mostly in wet streamheads and adjacent seepage slopes]
............ ............ ............ ..20 Stem leaves ovate, elliptic, obovate, oblong or lanceolate and corolla lip glabrous, or corolla lip pubescent basally, but leaves > 1.5 cm wide; calyx lobes toothed or entire.
............ ............ ............ ........23 Underside of corolla longitudinally striped with white (looks pinstriped with narrow blue/violet lines with broader white stripes); bracteoles borne above the middle of pedicels just below calyx tube (bracteoles are much smaller than leafy bract that is found at base of the petiole); calyx lobes entire and usually with some long, chaffy hairs on the margins; sinuses of calyx with small to large auricles; filament tube 12-15 mm long
............ ............ ............ ........23 Undersurface of corolla not noticeably striped with white; bracteoles located below middle of pedicels, often near base of leafy bract; calyx lobes toothed or entire and margins glabrous or ciliate with sharp-pointed hairs; sinuses of calyx lobes with or without auricles; filament tube 6-11 mm long.
............ ............ ............ ..........24 Calyx lobes distinctly toothed (leafy bract at base of pedicel also toothed).
............ ............ ............ ............ 25 Sinuses of calyx with prominent drooping auricles (resembling elongated ear lobes); calyx tube (hypanthium) typically densely long-hirsute (occasionally glabrous); stems densely pubescent, sparsely pubescent or sometimes almost glabrous
............ ............ ............ ............ 25 Sinuses of calyx lacking auricles or with very small and inconspicuous ones; calyx tube long-hirsute, smooth or glabrous with a warty texture (the bumps are often dark green to whitish); stems sparsely pubescent to glabrous.
............ ............ ............ ............ ..26 Lower lip of corolla completely glabrous; calyx tube mostly glabrous, occasionally with a few chaffy hairs or with a warty texture; [VA south to AL]
............ ............ ............ ............ ..26 Lower lip of corolla pubescent on upper surface near throat; calyx tube often conspicuously long-hirsute or occasionally glabrous with a warty texture (two forms often mixed in the same population); [endemic to the Apalachicola region of the FL Panhandle]
............ ............ ............ ..........24 Calyx lobes mostly entire or with a few lobes that are sparingly toothed (ignore leafy bract at the base of pedicel, which is often glandular-toothed).
............ ............ ............ ............ ....27 Auricles very large and conspicuous, covering almost half of calyx tube (resembling drooping ear lobes); lower corolla lip sometimes puberulent on the inside
............ ............ ............ ............ ....27 Auricles absent or smaller, less than 1/4 length of calyx tube; lower lip of corolla mostly glabrous on the inside.
............ ............ ............ ............ ......28 Stems usually densely pubescent throughout (also within inflorescence) with short or long hairs, but occasionally sparsely pubescent to almost glabrous; calyx lobes lanceolate and mostly erect, typically not flexuous or widely spreading; margins of calyx lobes often ciliate, occasionally smooth; calyx tube densely hirsute, sparsely hirsute to glabrous; auricles present or absent; corolla often pubescent on the outside, rarely glabrous.
............ ............ ............ ............ ........29 Stems puberulent to pubescent with short hairs; flowers many, spaced ca. 1 cm apart; calyx lobes narrowly triangular-lanceolate, not pilose at the base; [widespread in our area]
............ ............ ............ ............ ........29 Stems pilose with hairs to 1.5 mm long; flowers few, more widely spaced; calyx lobes ovate-cordate, abruptly tapered upwards, and with a dense tuft of pilose hairs at the base; [West Gulf Coastal Plain of w. LA and e. TX]
............ ............ ............ ............ ......28 Stems sparsely pubescent to glabrous, usually more hairy at the base and mostly glabrous within inflorescence (with only a few scattered hairs); calyx lobes linear or lanceolate and often spreading or flexuous (especially the tip, which are sometimes twisted); margins of calyx lobes glabrous (lacking cilia); calyx tube smooth to warty in texture, rarely sparsely hirsute; auricles absent to almost obsolete; corolla mostly glabrous on the outside.
............ ............ ............ ............ ..........30 Some calyx segments usually with slender, flexuous teeth (a few lobes occasionally not toothed or only remotely toothed near base, so check several flowers); leaves usually thick with a parchmentlike texture and often with a bluish to gray-green sheen when dried (typically strongly glaucous underneath); uppermost leaves distinctly sender-toothed with callus or gland-tipped teeth
............ ............ ............ ............ ..........30 All calyx segments entire, not toothed (ignore leafy bract at the base of pedicel, which is often glandular-toothed); leaves thick or thin, whitish to greenish underneath; uppermost leaves entire or toothed (with or without callus or gland-tipped teeth).
............ ............ ............ ............ ............ 31 Leaves usually thin and flexuous; leaf edges thin, not thickened; leaf shape elliptic, ovate or broadly lanceolate, mostly 1.5−4.5 cm broad; leaf margins toothed, shallowly crenate or almost entire; leaf apex rounded, obtuse or short acute; flowers loosely arranged; anther tube 2.5−3.5 mm; filament tube 5−7 mm long; [Mountains and Piedmont, rarely adjacent Coastal Plain]
............ ............ ............ ............ ............ 31 Leaves thick and stiff; leaf edges with an obvious thickened lip; leaf shape lanceolate to broadly lanceolate, usually less than 2.5 cm broad; leaf margins often distinctly toothed; leaf apex usually long-acute to acuminate; flowers usually densely arranged; anther tube close to 4 mm long; filament tube 8−11 mm long; [Atlantic Coastal Plain, rarely adjacent Piedmont]