Lythrum alatum

Herbs perennial, or subshrubs, slender or robust, 5–15 dm, green or slightly gray glaucous, glabrous. Stems erect, much-branched distally. Leaves oppo­site to subopposite proximally, alternate distally, branch leaves gradually smaller than those on main stem; sessile; blade ovate to oblong and base subcordate to rounded, or lanceolate to linear-lanceolate and base attenuate, 10–76 × 2–14 mm. Inflorescences racemes. Flowers alternate, sub­sessile, pedicel stout, distylous; floral tube cylindrical, 3–7 mm × 1 mm; epicalyx segments 2 times length of sepals; petals purple, obovate or oblong, 2–6.5 × 1.5–3 mm; nectary encircling base of ovary; stamens 6. Capsules septicidal or septifragal. Seeds ca. 30, obovoid to fusiform.

Distribution

North America, intro­duced in Mexico, West Indies.

Discussion

Varieties 2 (2 in the flora).

Taxonomic judgement has varied as to limits of Lythrum alatum and closely related taxa centered around it (L. californicum, L. flagellare, and L. ovalifolium). Identification of species from sympat­ric areas is often difficult and morphology suggests that hybridization occurs where ranges overlap. Lythrum californicum apparently hybridizes with L. alatum var. alatum in Kansas and Oklahoma, and with L. alatum var. lanceolatum in Oklahoma and eastern Texas. Variety lanceolatum may also hybridize with L. curtissiiin Calhoun County, Georgia, where they co-occur. A specimen combining features of L. alatum and L. flagellare is known from Hernando County, Florida.

Selected References

None.

Lower Taxa

Lythrum alatum var. alatum, Lythrum alatum var. lanceolatum

Key

1	Leaf blades ovate to oblong, bases subcordate to rounded; stems mostly less than 10 dm.	Lythrum alatum var. alatum
1	Leaf blades lanceolate to linear-lanceolate, bases attenuate; stems mostly greater than 10 dm.	Lythrum alatum var. lanceolatum