Flora of the Southeastern United States

1 Fruits 12-30 mm long, yellow, orange, or brown at maturity; petals unlobed (or with vestigial lateral lobes); petioles 14-51 mm long; leaf margins usually slightly to very obviously undulate; [peninsular FL (from Volusia and Manatee counties southwards)]

1 Fruits 4-15 mm long, purplish or black at maturity; petals 3-lobed (the lateral lobes comparable in size to the terminal lobe); petioles < 3 cm long; leaf margins planar or revolute; [collectively widespread in our region, including peninsular FL].

  2 Branches undifferentiated into short shoots and long shoots; branches unarmed; ovary glabrous; large trees to 25 m tall (though often smaller); [tropical s. FL (from Martin and Collier counties southwards)].

  2 Branches differentiated into short shoots (bearing most leaves, with very short internodes) along long shoots; branches armed with thorns; ovary pubescent at anthesis (becoming glabrous in fruit); small trees or shrubs, less typically medium trees to 20 m tall; [collectively widespread in our region, including tropical s. FL].

    3 Leaves, twigs, pedicels, and sepals glabrous even when young (or with a very few and inconspicuous white strigose hairs); leaf blades not conspicuously reticulate on the lower surface; styles 2.2-2.8 mm long; [se. and s. TX southwards, FL peninsula (Brevard and Levy counties southwards)].

    3 Leaves, twigs, pedicels, and sepals with densely to sparsely hairy surfaces (at least when young); leaf blades conspicuously reticulate on the lower surface (the secondary, tertiary, and finer veins impressed or flush to the lower leaf surface when fresh, slightly to strongly raised when dry (the reticulum is hard to observe in species with dense and persistent vestiture); styles 0.9-1.8 mm long; [section Frigoricola].

      4 Lower leaf surfaces hairy only when leaves are very young, quickly sloughing all or most hairs to become entirely glabrous or with hairs only on the midvein.

        5 Petioles densely shaggy-strigose, the hairs white to gray; [dry habitats, c. OK, c. TX, s. TX westwards and southwards]

        5 Petioles glabrous or sparsely pubescent with blonde to light brown hairs; [collectively widespread, from e. TX eastwards].

          6 Berries (7-) 9-16 mm long; central corolla lobe 1.8-2.0 mm long; leaf trichomes transparent and colorless, often flattened in ×-section (use at least 20× magnification); stomatal chamber openings closed to a narrow slit, the guard cells not visible through the opening; [widespread in our region]

          6 Berries 4-9 mm long; central corolla lobe 1.1-1.3 mm long; leaf trichomes opaque, light brown to gray, mostly terete in ×-section; stomatal chamber openings wide and elliptic, the guard cells visible through the opening; [moist to wet habitats, SC, GA, and FL west to sw. LA]

      4 Lower leaf surfaces persistently (through the season) hairy (on the surface and not just on the midvein, either slightly to densely sericeous to woolly.

             7 Leaf pubescence dense, sericeous to sericeous-tomentulose, the trichomes appressed and co-oriented, leaf surface obscured by pubescence.

               8 Young twigs glabrous or with a few scattered, quickly deciduous pale trichomes; twig surface green to cream-white, becoming light grey; leaf pubescence silvery-white to very slightly golden

               8 Young twigs densely pubescent; twig surface dark brown to red-brown; leaf pubescence golden to rusty brown.

                 9 Mean pedicel length (2-) mean 4.8 (-11) mm long; largest leaves on short shoots almost all < 4.5 cm long; leaf undersurface typically tawny to very dark brown, and appears dull and finely woolly, rarely silky-sericeous; plants usually clonal shrubs; [c. FL ridges]

                 9 Mean pedicel length (4-) mean 9.3 (-15) mm long; largest leaves on short shoots to 8 cm long (usually some at least on a plant > 5 cm long); leaf undersurface tawny to light golden to even silvery-white, most often appearing silky and lustrous, when dull and woolly, with most trichomes straight, appressed, multi-layered, and co-oriented, completely obscuring the leaf surface, but with a large proportion of trichomes that are curled and ascending, dulling the luster; plants usually many-stemmed, clumped shrubs to single-trunked trees; [e. NC south to s. FL, mainly in maritime situations]

             7 Leaf pubescence moderate to sparse, wooly, the trichomes ascending to appressed, not co-oriented, leaf surface visible, not obscured by pubescence.

                   10 Plants strongly stoloniferous; mature plants usually < 1 m tall; fruit > 1 cm long.

                     11 Pubescence on young twigs moderate to dense, blonde to light brown, rarely persisting past the first season; abaxial leaf pubescence blonde to light brown, sparse; staminodes only to 1/3 to 1/2 the length of the median corolla lobes; ovary glabrous or with a few trichomes medially; seed uniformly brown; stomatal chamber openings atop ellipsoidal domes neatly bordered by one or more concentric cuticular ridges

                     11 Pubescence on young twigs dense, rusty dark red-brown, often persisting well past the first season; abaxial leaf pubescence rusty red-brown, sparse to moderately dense, often giving surface a distinctly reddish hue; staminodes nearly as long as median corolla lobes; ovary densely pubescent; seed variegated; stomatal chamber openings located on raised, donut-shaped platforms

                   10 Plants not strongly stoloniferous; mature plants often > 1 m tall; fruit usually < 1 cm long.

                       12 Leaf vein reticulum evident but not boldly conspicuous, highest-order veins quaternary; stomatal chamber openings closed to a narrow slit, guard cells not visible through opening

                       12 Leaf vein reticulum conspicuous, highest-order veins quinternary; stomatal chamber openings wide and elliptic, guard cells visible through opening.

                          13 Young twigs glabrous or nearly so, and abaxial leaf pubescence finely wooly; s. peninsular FL]

                          13 Young twigs densely pubescent, and abaxial leaf pubescence woolly; [c. FL north and west to OK, TX, and ne. Mexico].

                            14 Pubescence of leaves white, dense, woolly but matted, many of the trichomes straight and appressed; [se. to c. TX south to ne. Mexico]