Flora of the Southeastern United States
2022 Edition


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Key to Sida

1 Leaves deeply palmately lobed; plants 1-2 (-4) m tall; petals white
1 Leaves unlobed; plants 0.2-1 m tall; petals yellow.
..2 Mericarps, styles, and stigmas 5; stem with a spine subtending each leaf; leaves usually truncate to subcordate at the base; [section Spinosae]
..2 Mericarps, styles, and stigmas (6-) avg. 10 (-14); stem lacking spines subtending the leaves; leaves usually cuneate to rounded (cordate to subcordate in S. cordifolia) at the base.
....3 Leaves cordate to subcordate at the base; flowers clustered into a terminal panicle; [section Cordifoliae]
....3 Leaves cuneate to rounded at the base; flowers solitary in leaf axils.
......4 Leaves elliptic-rhombic, mostly 2-3× as long as wide; [section Sidae].
........5 Leaves and branches borne distichously; stipules usually falcate, several-veined
........5 Leaves and branches borne spirally; stipules linear, 1 (-3)-veined
......4 Leaves narrowly elliptic to linear, (3-) 4-20× as long as wide; [section Ellipticifoliae].
..........6 Stipules 1.5-2× as long as the petiole, linear; leaf blade narrowly rhombo-elliptic, 4-6× as long as wide, glabrate above; seeds pubescent apically and ventro-apically; peduncles 0.5-2 (-3) cm long, 0.5-0.75× as long as the subtending leaf, articulated ca. 0.5-1 cm below the calyx; [endemic to peninsular Florida]
..........6 Stipules 0.5-1× as long as the petiole, falcate or subulate, not linear; leaf blade linear, lance-linear to narrowly elliptic, (3-) 4-21× as long as wide, but if (3-) 4-6× as long as wide then the leaves crenulate-serrate and the peduncle not articulated; seeds glabrous to apically pubescent, usually ventro-apically glabrous; peduncle 0.5-1.25× as long as the subtending leaf, but if articulated then 0.75-1.25× as long; [collectively more widespread].
............ 7 Peduncles 2-6 cm long, approximately equal or somewhat exceeding the subtending leaf, articulated 1-2 cm below the calyx with the articulation becoming most prominent on mature, fruiting peduncles; flowers strictly axillary; [of LA westwards]
............ 7 Peduncles 0.5-4.5 cm long, shorter than the subtending leaf (rarely exceeding it in S. elliottii), not articulated; flowers axillary to aggregated apically; [collectively more widespread].
............ ..8 Leaf margins crenulate-serrate, more densely so toward apex; lower surface venation prominently greenish yellow with venation inconspicuous on upper surface; calyx lobes apically acuminate to weakly caudate, tricolorous, yellowish to greenish cream at base, becoming green and then darker green distally
............ ..8 Leaf margins evenly serrate; venation not conspicuous; calyx lobes apically acute to weakly acuminate; essentially monochrome, green at base.
............ ....9 Calyx stellate-pubescent, usually villous-hirsute at base and along veins; flowers axillary to apically congested; leaves linear to narrowly elliptic, purplish along margins or not, glabrate to stellate and simple-pubescent above; plants to 1 m tall; [widespread in our area, south to ne. and Panhandle FL]
............ ....9 Calyx stellate-pubescent, villous hairs absent; flowers axillary; leaves linear, usually purplish along margins, glabrate above; plants to 0.5 m tall; [peninsular Florida]