Herbs, usually annual, sometimes perennial. Stems prostrate to decumbent or ascending, diffusely branched, terete, becoming ridged on drying, to 1(–1.5) m, somewhat succulent, densely hairy to glabrate. Leaves opposite, even-pinnate, one of each pair alternately smaller or sometimes abortive; stipules persistent, herbaceous, falcate, apex acuminate; petiolules very short to absent, less than 1 mm; leaflets 6–16(–20), opposite, distinct, elliptic to broadly oblong, ovate, or obovate, ± unequal in size, those on one side of rachis slightly smaller, base oblique, apex acute to obtuse, mucronate to apiculate, surfaces hairy to glabrate, terminal pair pointed forward. Pedicels emerging from axils of alternately smaller leaves, erect, usually reflexed in fruit. Flowers solitary, regular; sepals usually persistent, rarely deciduous, 5, distinct, green, equal, margins scarious, apex acute to obtuse, hairy; petals fugacious, usually marcescent, 5, convolute, spreading hemispherically, not twisted, white to bright orange, base white to bright orange or green to red, obovate, base not clawed, apex rounded to truncate, sometimes irregularly notched; nectary 5 2-lobed glands at bases of filaments opposite sepals; stamens 10, 5 opposite petals somewhat longer; filaments adnate at base to petals, filiform, subulate, or rarely basally winged, unappendaged; anthers usually ovoid to oblong [or globose], rarely linear, those opposite sepals rarely aborting; ovary sessile, 10-lobed, 10-locular, glabrous or hairy; ovules 1 per locule, sometimes 1 or more aborting; style persisting, forming beak on fruit; stigma terminal, rarely extending down distal 1/3 [almost to base] of style, 10-ridged or obscurely 10-lobed, capitate, oblong, or clavate, papillose, rarely coarsely canescent. Fruits schizocarps, ovoid [pyramidal or conic], 10-lobed, at maturity dividing septicidally and separating from persistent styliferous axis into 10, or sometimes fewer, mericarps; mericarps obliquely triangular, wedge-shaped, tuberculate, rugose, cross-ridged, or ± keeled abaxially, not spiny. Seeds 1 per mericarp, white, oblong-ovoid.
Habitat: Open, disturbed, dry habitats.
United States, Mexico, West Indies, Central America, South America.
Species 17 (6 in the flora).
Kallstroemia is the largest New World genus of the family. Kallstroemia pubescens (D. Don) Dandy, native to the Caribbean, was collected in the United States at least six times in four states (Arizona, Florida, Georgia, and Texas) between 1833 and 1898, but apparently has not become naturalized. It most closely resembles K. hirsutissima and K. maxima, and is to be expected in sandy, coastal areas from Georgia to Florida and along the Gulf Coast to Texas. Kallstroemia pubescens can be distinguished from K. hirsutissima by having leaflets that are appressed-hairy to glabrate (versus densely hirsute) and sepals that are lanceolate and spreading in fruit with sharply involute margins (versus subulate, clasping the fruit, and with only the scarious margins involute). It can be distinguished from K. maxima by having ovaries and fruits that are densely hairy (versus glabrous or sometimes basally strigose) and styles that are densely short-pilose at the base (versus glabrous).
|1||Leaves obovate in outline, terminal pairs of leaflets largest.||> 2|
|2||Sepals usually deciduous; mericarps tuberculate, 4–5 tubercles oblong, 1–1.5 mm, other tubercles rounded, much less than 1 mm.||Kallstroemia californica|
|2||Sepals persistent; mericarps tuberculate, cross-ridged, or slightly keeled, tubercles if present all rounded, to 1 mm.||> 3|
|3||Schizocarps strigillose; styles hairy.||Kallstroemia hirsutissima|
|3||Schizocarps usually glabrous, sometimes strigose at base, or rarely to base of beak; styles glabrous.||Kallstroemia maxima|
|1||Leaves elliptic in outline, middle pairs of leaflets largest.||> 4|
|4||Plants perennial; stigmas extending along distal 1/3 of style.||Kallstroemia perennans|
|4||Plants annual; stigmas terminal.||> 5|
|5||Flowers 20–60 mm diam.; petals 10–34 × 7–22 mm, 2-colored; pedicels in fruit 30–105 mm.||Kallstroemia grandiflora|
|5||Flowers 8–25 mm diam.; petals 3–12 × 2.5–5 mm, 1-colored; pedicels in fruit 8–40 mm.||> 6|
|6||Pedicels shorter than subtending leaves; sepals usually deciduous; petals yellow, 3–6 × 2.5–3 mm.||Kallstroemia californica|
|6||Pedicels usually longer than, sometimes equaling, subtending leaves; sepals persistent; petals orange, 5–12 × 3.5–5 mm.||Kallstroemia parviflora|