Ludwigia glandulosa


Fl. Carol., 88. 1788.

Treatment appears in FNA Volume 10.

Herbs slender, forming stolons 5–20 cm, 0.4–0.8 mm thick. Stems erect, slightly ridged, usually well branched, 10–80(–100) cm, glabrate or often with strigillose raised lines de­current from leaf axils. Leaves alternate; stipules ovate-triangular, 0.15–0.35 × 0.05–0.25 mm, succulent; stolons: petiole attenuate, 0.3–1 cm, blade narrowly elliptic, 1.5–3.5(–5.5) × 0.5–1.3(–2) cm; main stem: petiole 0–1.5 cm, blade usually narrowly elliptic to elliptic, sometimes linear, 3–12 × 0.3–2.1 cm, base attenuate, margins subentire with hydathodal glands often visible, apex acute to very narrowly acute, surfaces densely papillose-strigillose, abaxial veins glabrous or sparingly, minutely strigil­lose; leaves on side branches usually reduced, 0.8–4.5 ×0.2–1 cm; bracts much reduced. Inflorescences open, leafy racemes or spikes, flowers solitary in axils, often congested, especially on branches; bracteoles attached on pedicel at base of ovary or to 2 mm distal to base, narrowly lanceolate to sublinear, 0.4–1 × 0.1–0.4 mm, apex acuminate, surfaces glabrate. Flowers: sepals ascending, light green, ovate-deltate, 1.1–2.3 × 1–1.8 mm, margins entire, fringed with minute, strigillose hairs, apex short-acuminate or acute, surfaces glabrous; petals 0; filaments nearly translucent, 0.6–1.1 mm, anthers 0.3–0.5 × 0.3–0.6 mm; pollen shed in tetrads; ovary subcylindric, 2–5 × 0.8–1.9 mm; nectary disc ele­vated 0.3–0.4 mm on ovary apex, light green, 0.6–1.8 mm diam., 4-lobed, glabrous or minutely papillose; style pale green, 0.3–0.8 mm, glabrous, stigma broadly clavate to subglobose, 0.2–0.5 × 0.2–0.5 mm, not exserted beyond anthers. Capsules subcylindric, sub­terete to obscurely 4-angled with 4 shallow grooves, 2–8(–9) × 1.3–2(–3) mm, hard-walled, irregularly dehiscent, pedicel 0–0.3(–0.5) mm. Seeds light brown, kidney-shaped with slightly pointed ends, 0.5–0.8 × 0.3–0.4 mm, surface cells columnar, elongate either parallel or transversely to seed length. 2n = 32.


c, e United States.


Subspecies 2 (2 in the flora).

Ludwigia glandulosa consists of two subspecies: subsp. glandulosa is very common and widespread throughout the Atlantic and Gulf coastal plains and the Mississippi Embayment, westward to eastern Texas and southeastern Oklahoma; subsp. brachycarpa grows only in the western portion of the range of subsp. glandulosa, extending farther west in Texas and Oklahoma. The two taxa grow in similar habitats, but subsp. glandulosa prefers drier habitats farther south and west. The general distinctiveness of these subspecies is probably maintained by their modal autogamy; vegetative reproduction by means of stolons may likewise play a role in preserving favored genotypes (C. I. Peng 1989).

Selected References



1 Capsules (4–)5–8(–9) mm; cauline leaf blades 3.2–12 × 0.4–2.1 cm; seeds: surface cells elongate parallel to seed length. Ludwigia glandulosa subsp. glandulosa
1 Capsules 2–5 mm; cauline leaf blades 3–5(–7) × 0.3–0.5(–1) cm; seeds: surface cells elongate transversely to seed length. Ludwigia glandulosa subsp. brachycarpa