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flaxleaf seedbox, southeastern primrose-willow

Simpson's primrose-willow

Habit Herbs slender, rarely with aerenchyma, forming slender stolons 4–15(–30) cm, 0.7–1(–1.5) mm thick. Herbs sometimes creeping and rooting at nodes, new shoots arising from trailing stems or main caudex, rarely forming stolons.
Stems

erect or ascending, slightly ridged, usually well branched, 12–55(–62) cm, glabrous.

erect, ascending, decumbent, or prostrate, slightly ridged, well branched, 10–60(–75) cm, glabrous, with raised lines decurrent from leaf axils.

Leaves

alternate;

stipules narrowly ovate to narrowly lanceolate, 0.2–0.3 × 0.1–0.2 mm;

stolons: petiole narrowly attenuate, 0.05–0.5 cm, blade narrowly obovate or oblanceolate to spatulate, 0.5–2 × 0.1–0.6 cm;

stems: sessile, blade linear to linear-oblanceolate, 1.5–4 × 0.1–0.4(–0.6) cm, base very narrowly cuneate, margins entire with obscure hydathodal glands, apex acuminate to acute;

bracts linear, reduced.

alternate or proximal pairs opposite;

stipules narrowly ovate-deltate, 0.1–0.3 × 0.1–0.2 mm, succulent;

petiole winged, 0.2–1 cm, blade spatulate or oblanceolate to very narrowly oblanceolate or sublinear, 0.6–1.5(–2) × (0.1–)0.3–0.7(–1.1) cm, base attenuate, margins subentire with hydathodal glands, apex acute or mucronate;

bracts not much reduced.

Inflorescences

leafy spikes, flowers solitary in leaf axils;

bracteoles attached 0–1.5 mm distal to base of ovary, very narrowly oblanceolate to linear, (1.5–)2.5–9(–13) × 0.2–0.8 mm, margins entire, apex acute.

open, leafy spikes or racemes, flowers solitary in leaf axils;

bracteoles attached in opposite pairs near base of ovary, lanceolate-elliptic, 0.9–1.5(–2.5) × 0.4–0.9 mm, swollen at base, apex acuminate.

Flowers

sepals ascending, green, narrowly lanceolate-deltate, (3–)4–7 × 1.1–1.7 mm, margins entire, apex narrowly acute, surfaces glabrous or minutely papillose;

petals narrowly obovate-elliptic, 4–6 × 2–4 mm, base obtuse, apex obtuse or rounded;

filaments pale yellow, (1.3–)1.5–2.5(–3) mm, anthers oblong, 0.6–1.1 × 0.5–0.8 mm;

pollen shed in tetrads;

ovary subcylindric, 3–4 × 1–1.5 mm;

nectary disc elevated 0.3–0.7 mm on ovary apex, bright yellow, 0.8–1.5 mm diam., prominently 4-lobed, minutely papillose;

style yellow, 1.25–2.5 mm, glabrous, stigma subcapitate, 0.3–0.6 × 0.6–0.8 mm, shallowly 4-lobed, not exserted beyond anthers.

sepals ascending, creamy white near base adaxially, ovate-deltate, 1.2–1.8 × 1–2 mm, margins entire, apex narrowly acute or acuminate, surfaces glabrous;

petals 0 or very rare;

filaments nearly translucent, 0.5–0.8 mm, anthers 0.2–0.4 × 0.3–0.4 mm;

pollen shed singly;

ovary obconic, subterete or scarcely 4-angled, 1.2–1.8 × 1.2–2 mm;

nectary disc elevated 0.3–0.4 mm on ovary apex, green, 0.9–1.3 mm diam., distinctly 4-lobed, glabrous;

style pale green, 0.4–0.6 mm, stigma pale yellow, subglobose, 0.2–0.3 × 0.2–0.3 mm, not exserted beyond anthers.

Capsules

subcylindric, terete or slightly angled, 5–10(–12) ×1.3–2(–2.2) mm, hard-walled, irregularly dehiscent, pedicel 0 mm.

obconic, obscurely 4-angled, 1.5–2.5 × 1.5–3 mm, hard-walled, dehiscent by loculicidal slits, pedicel 0–0.4 mm.

Seeds

reddish brown, oblong-elliptic, 0.6–0.7 × 0.2–0.3 mm, surface cells nearly isodiametric.

light brown or brown, ellipsoid, 0.5–0.6 × 0.3–0.4 mm, surface cells transversely elongate, glabrous, occasionally covered by minute waxy hairs.

2n

= 16.

= 48.

Ludwigia linifolia

Ludwigia simpsonii

Phenology Flowering late Jun–Oct. Flowering Apr–Nov (year-round).
Habitat Drainage ditches, margins of creeks or swamps, open edges of cypress swamps, moist pinelands, edges of brackish lakes. Sandy, peaty ditches, open pineland swamps, edges of cypress swamps, tidal flats and nearby marshes, limestone sinks.
Elevation 0–300 m. (0–1000 ft.) 0–50 m. (0–200 ft.)
Distribution
from FNA
AL; FL; GA; MS; NC; SC; Mexico (Tabasco)
[BONAP county map]
from FNA
FL; MS; West Indies (Cuba, Jamaica)
Discussion

Ludwigia linifolia is primarily a coastal species that extends farther inland in Georgia and the Carolinas. Being one of five diploids in sect. Isnardia, it has particularly prominent nectary lobes and appears to be modally outcrossing (C. I. Peng 1989). It also is known from a disjunct population on the Yucatán Peninsula in Tabasco, Mexico.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Ludwigia simpsonii is a hexaploid species occurring primarily in Florida, with outlier populations in southern Mississippi, western Cuba, and Jamaica. The species grows frequently in close proximity to L. curtissii; it grows mainly along roadside ditches with other weeds, whereas L. curtissii grows in less disturbed habitats, and the two seldom occur side by side (C. I. Peng 1989). Peng (1988, 1989) suggested that the hexaploid (2n = 48) L. simpsonii and the diploid (2n = 16) L. microcarpa gave rise to L. curtissii, the only octoploid (2n = 64) in sect. Isnardia.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Isnardia Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Isnardia
Sibling taxa
L. alata, L. alternifolia, L. arcuata, L. bonariensis, L. brevipes, L. curtissii, L. decurrens, L. erecta, L. glandulosa, L. grandiflora, L. hexapetala, L. hirtella, L. lanceolata, L. leptocarpa, L. linearis, L. maritima, L. microcarpa, L. octovalvis, L. palustris, L. peploides, L. peruviana, L. pilosa, L. polycarpa, L. ravenii, L. repens, L. simpsonii, L. spathulata, L. sphaerocarpa, L. suffruticosa, L. virgata
L. alata, L. alternifolia, L. arcuata, L. bonariensis, L. brevipes, L. curtissii, L. decurrens, L. erecta, L. glandulosa, L. grandiflora, L. hexapetala, L. hirtella, L. lanceolata, L. leptocarpa, L. linearis, L. linifolia, L. maritima, L. microcarpa, L. octovalvis, L. palustris, L. peploides, L. peruviana, L. pilosa, L. polycarpa, L. ravenii, L. repens, L. spathulata, L. sphaerocarpa, L. suffruticosa, L. virgata
Synonyms Isnardia linifolia L. cubensis, L. curtissii var. simpsonii
Name authority Poiret in J. Lamarck et al.: Encycl., Suppl. 3: 513. (1814) Chapman: Fl. South. U.S. ed. 2 repr. 2, 685. (1892) — (as simpsoni)
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