Lythrum salicaria L.
purple loosestrife
Hairy, perennial herb; stems erect, ± quadrangular, 1-2 m tall, pink towards base. Lvs sessile, 20-95 × 5-27 mm (smaller just below infl.), lanceolate, oblong-lanceolate or narrow-elliptic, with short hairs beneath, especially on veins, sometimes becoming glabrous above, entire, ciliolate; base usually rounded to cordate, sometimes amplexicaul; apex usually acute, sometimes subacuminate. Infl. terminal, branched, main axis to nearly 25 cm long, densely hairy. Fls usually dense except on lower branches, usually in whorls of 3-7, sometimes 1-2 in axils of bracts, or to 15 per whorl, tristylous. Pedicels c. 0.5 mm long; bracteoles much > pedicels. Calyx 6-8 mm long, broad-cylindric, often purplish, with prominent ribs, hairy; calyx lobes ± triangular; epicalyx segments 1.5-2.5 mm long, subulate, much > lobes, densely hairy. Petals 6, 9-15 mm long, rose or rosy purple, crumpled; claw short; limb oblong-elliptic or oblong-obovate. Stamens usually 12, usually 6 exserted and 6 included, rarely all exserted. Style to 7 mm long, with stigma at varying levels in different plants. Capsule included, 3-5 mm long, ellipsoid or ovoid-ellipsoid, blackish. Seeds 0.8-1.2 mm long, narrow-ovoid to almost oblong, ± flattened and keeled on one side.
N.: several places around Lake Horowhenua (Manawatu); S.: occasional in Canterbury, Otago, and Southland, but fairly common in the Christchurch area.
Europe, N. Africa, W. Asia 1958
Escape from cultivation, usually in damp places along stream banks, ditches and lakesides, sometimes in fairly dry waste sites.
FL Dec-Feb.
Purple loosestrife is widely cultivated and is illustrated in Fig. 78. It has long been known to be tristylous, and all 3 different fl. types have been observed in N.Z. (C. J. Webb pers. comm.). A closely related sp., L. virgatum L., is commonly cultivated in some areas of the South Id but has not become wild. This is a smaller, glabrous plant with narrower lvs and the epicalyx segments = calyx lobes.
