Cuphea

Herbs, annual or perennial, [subshrubs], terrestrial [amphibious], 1–10 dm, [glaucous], often glandular-viscid with 1+ types of glandular/eglandular indument, trichomes colorless, white, or red-purple [glabrous]; with fibrous roots or woody xylopodium. Stems erect, decumbent, or spreading, branched or unbranched. Leaves usually opposite, rarely 3- or 4-whorled, when whorled, opposite at proximal nodes; sessile, subsessile, or petiolate; blade ovate to lanceolate, oblong, elliptic, or linear, base attenuate or rounded [cuneate, cordate], surfaces finely scabrous. Inflorescences indeterminate, terminal or axillary, leafy or bracteate racemes [thyrses], 1 flower emerging between petioles at a node, others, when present, on axillary branchlets. Flowers sessile or pedicellate, zygomorphic, monostylous; floral tube perigynous, cylindrical, rounded, or spurred basally, conspicuously 12-ribbed, inner surface villous or glabrous; epicalyx segments shorter than sepals [to longer than sepals]; sepals 6, to 1/4 floral tube length; petals caducous [persistent], [0 or](2–)6, purple, rose purple, rose, or pink, subequal or unequal, sometimes 2 upper petals larger or of different color than others; nectary present at base of ovary; stamens (5–)11, deeply included or equal to surpassing sinus of sepals, 2 stamens usually shorter, more deeply inserted than others; ovary 2-locular; placenta elongate; septa reduced to thin threads, 1 locule reduced; style slender; stigma capitate to punctiform. Fruits capsules, walls thin and dry, dehiscence by longitudinal complementary slits in wall and floral tube, placenta and seeds ultimately exserted. Seeds 3–13(–20)[–100+], orbiculate, suborbiculate, oblong, or elliptic in outline; cotyledons ± complanate.

Distribution

North America, Mexico, West Indies, Central America, South America, Pacific Islands, Australia.

Discussion

Species ca. 240 (6 in the flora).

The seeds of Cuphea store oils composed of medium-chain fatty acids that are widely used in the manufacture of soaps and detergents, in specialized food products, and in medicine. The endemic C. viscosissima is under development as a domestic source of the fatty acids that traditionally have been obtained from imported palm oils. Other species are cultivated as annual garden plants, and new hybrids and cultivars appear yearly in the nursery trade. Among the most popular cultivated species are: C. calophylla Chamisso & Schlechtendal and C. hyssopifolia Kunth, both sold under the name Mexican heather and identified by their small, tubular flowers with six purple petals; C. ignea A. de Candolle, the cigar flower or firecracker plant, a species with trailing stems and elongate, red flowers with black and white tips; and C. llavea Lexarza, marketed as ‘Tiny Mice’ or ‘Bat-Faced Cuphea,’ which has two large, red petals often with a black spot at the base, and purple trichomes filling the opening of the floral tube. The purple-petalled C. procumbens Ortega (firefly cuphea) and hybrids of C. procumbens with C. llavea are also popular flowering annuals. Garden escapes of C. procumbens account for reports in Florida, Georgia, Massachusetts, North Carolina, and South Carolina; the species does not appear to be naturalized anywhere in the flora area. All the cultivated species named above are native to Mexico.

Selected References

None.

Lower Taxa

Cuphea aspera, Cuphea carthagenensis, Cuphea glutinosa, Cuphea strigulosa, Cuphea viscosissima, Cuphea wrightii

Key

1	Leaves 3- or 4-whorled mid stem; flowers opposite or 3- or 4-whorled; pedicels 4–25 mm.	Cuphea aspera
1	Leaves opposite; flowers alternate; pedicels 0–6 mm.	> 2
2	Stamens deeply included, extending 2/3 distance to sinus of sepals; floral tube 4–6 mm.	Cuphea carthagenensis
2	Stamens reaching or surpassing sinus of sepals; floral tube 5–12 mm.	> 3
3	Sepals equal; leaves sessile or subsessile, petiole 0–2 mm; seeds 1.5–2 mm.	> 4
3	Sepals unequal, adaxialmost longer; leaves petiolate (at least proximally), petiole (1–)2–15(–20) mm; seeds 2–2.8 mm.	> 5
4	Floral tube bases rounded; seed margins rounded.	Cuphea glutinosa
4	Floral tube bases descending spurs; seed margins flattened, thin.	Cuphea strigulosa
5	Leaf blade bases attenuate; seeds 7–10; upper petals 3–6 mm.	Cuphea viscosissima
5	Leaf blade bases rounded to cuneate; seeds 3–6; upper petals 1–2 mm.	Cuphea wrightii