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Published In: Species Plantarum 1: 446. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 8/25/2017)
Acceptance : Accepted

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5. Lythrum L. (loosestrife)

Plants terrestrial or strongly emergent aquatics, perennial (annual elsewhere), fibrous-rooted, occasionally rooting at the lower nodes, with rhizomes and/or offsets, often forming colonies. Stems more or less wandlike, erect or ascending, not arched, herbaceous or sometimes woody at the very base, glabrous or hairy, more or less 4-angled in cross-section, usually few- to many-branched, mostly well above the base. Leaves opposite or at least the upper leaves alternate (the lowermost leaves rarely in whorls of 3 in L. alatum), sessile or very short-petiolate. Leaf blades linear or more commonly narrowly to broadly lanceolate or oblong-lanceolate or triangular-lanceolate, angled or tapered to a bluntly or sharply pointed tip, sometimes the lowermost leaves more or less rounded at the tip, rounded or more commonly truncate to shallowly cordate at the base, glabrous or hairy. Inflorescences either axillary or terminal, if terminal then appearing spicate, the flowers individually sessile or with stalks to 3 mm long. Flowers actinomorphic or nearly so, the hypanthium much longer than wide, cylindrical, symmetric at the base (not pouched or spurred), not or only slightly oblique at the tip, the hypanthium plus sepals 3–7 mm long, with 8–12 longitudinal ridges. Sepals (4–)6, triangular to broadly triangular, more or less ascending, the appendages about twice as long as the sepals, thickened, narrowly conic-triangular, arched outward. Petals (4–)6, 3–12 mm long, reddish pink to purple (rarely white elsewhere), sometimes somewhat contorted, but not appearing ruffled or crinkled, not persistent at fruiting. Stamens (4–)6 or 12, those of different flowers with filaments of potentially 3 different lengths (those of an individual flower of 1 or 2 lengths), the anthers exserted or not, yellow or dark purple. Pistils sometimes with a nectary disc, the ovary completely or more commonly incompletely 2-locular, the styles of potentially 3 different lengths in different flowers, exserted or not. Fruits 4–6 mm long, narrowly ovoid to oblong-ellipsoid capsules, dehiscing longitudinally (sometimes irregularly) along the partitions between the two locules, the outer wall with a network of minute ridges (observed with magnification). Seeds numerous (often 100 or more), 0.4–1.2 mm long, ovate to somewhat tetrahedral in outline, asymmetrically 4-sided (1 side broader than the other 3) with rounded angles, the surface minutely roughened or pebbled, shiny, tan to yellowish brown. About 30 species, North America, Europe, Asia, Africa, Australia.

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