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Key to families | Table of families and genera

Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.

 

LUDWIGIA FALSE LOOSESTRIFE, WATER PRIMROSE

Peter C. Hoch & Brenda J. Grewell


Annual to subshrub or emergent aquatic, often floating, rooting at nodes. Leaf: alternate to opposite. Inflorescence: spike; flowers 1 per bract. Flower: radial; hypanthium 0; sepals 4–5(7), persistent; petals (0)4–5(7), white to yellow; stamens 4 or 10(12), pollen generally shed singly (in California); stigma club-shaped to spheric. Fruit: irregularly dehiscing; wall thick or thin. Seed: free or embedded in woody piece of fruit wall.
82 species: ± worldwide. (C.G. Ludwig, German botanist, physician, 1709–1773) [Raven 1963 Reinwardtia 6:327–427] Many polyploids.

Key to Ludwigia

1. Leaves opposite; sepals 4; petals 0 or 4, 1–3 mm; stamens 4; fruit 1–10 mm, erect; seed free from fruit wall (sect. Isnardia)

2. Petals 0; sepals 1.1–2 mm; fruit 1.5–5 mm; pedicels 0–0.5 mm; ovary with 4 green stripes ..... L. palustris

2' Petals 4; sepals 1.8–5 mm; fruit 4–10 mm; pedicels 0–3 mm; ovary not striped ..... L. repens

1' Leaves alternate; sepals (4)5(6); petals (4)5(6), 9–29 mm; stamens (8)10(12) in 2 unequal sets; fruit 10–32 mm, generally reflexed; seeds embedded in woody inner fruit wall (sect. Oligospermum)

3. Bracts lanceolate to lance-ovate; sepals 8–19 mm; petals 15–29 mm

4. Stem generally ± glabrous; pedicels 13–25(47) mm; sepals 8–12(15) mm; petals 15–18(20) mm; fruit 13–25(27) mm, ± glabrous ..... L. grandiflora

4' Stem glabrous to spreading-hairy; pedicels (9)13–25(85) mm; sepals 12–19 mm; petals 18–29 mm; fruit 14–26 mm, ± spreading-hairy ..... L. hexapetala

3' Bracts deltate; sepals 6–14 mm; petals 9–22 mm ..... L. peploides

5. Plant ± spreading-hairy (except stem base); leaf tip generally mucronate; sepals spreading-hairy; petals 10–16(22) mm; fruit (20)24–32 mm ..... subsp. montevidensis

5' Plant generally glabrous to ± glabrous; leaf tip generally not mucronate; sepals ± glabrous; petals 9–13 mm; fruit 10–17(20) mm ..... subsp. peploides

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Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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