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Simpson's primrose-willow

creeping seedbox, cylindricfruit primrose-willow

Habit Herbs sometimes creeping and rooting at nodes, new shoots arising from trailing stems or main caudex, rarely forming stolons. Herbs slender, forming stolons 5–20 cm, 0.4–0.8 mm thick.
Stems

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

erect, slightly ridged, usually well branched, 10–80(–100) cm, glabrate or often with strigillose raised lines decurrent from leaf axils.

Leaves

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.

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 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.

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, 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.

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

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

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

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

= 48.

= 32.

Ludwigia simpsonii

Ludwigia glandulosa

Phenology Flowering Apr–Nov (year-round).
Habitat Sandy, peaty ditches, open pineland swamps, edges of cypress swamps, tidal flats and nearby marshes, limestone sinks.
Elevation 0–50 m. (0–200 ft.)
Distribution
from FNA
FL; MS; West Indies (Cuba, Jamaica)
from USDA
c United States; e United States
[WildflowerSearch map]
[BONAP county map]
Discussion

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.)

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).

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

Key
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.
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.
subsp. brachycarpa
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. 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
L. alata, L. alternifolia, L. arcuata, L. bonariensis, L. brevipes, L. curtissii, L. decurrens, L. erecta, 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. simpsonii, L. spathulata, L. sphaerocarpa, L. suffruticosa, L. virgata
Subordinate taxa
L. glandulosa subsp. brachycarpa, L. glandulosa subsp. glandulosa
Synonyms L. cubensis, L. curtissii var. simpsonii
Name authority Chapman: Fl. South. U.S. ed. 2 repr. 2, 685. (1892) — (as simpsoni) Walter: Fl. Carol., 88. (1788)
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