Distribution: Moist places, especially where disturbed, in North America from Newfoundland to Alaska, south to Baja California, Sonora, New Mexico, and Virginia. Widely naturalized in Europe, especially in the north-west, and also in the Hawaiian Islands (Raven 1967a). In Australasia, it occurs in waste places, especially where moist, and in swamps, along rivers, and about ponds, and also as a garden weed. In Australia itself, it grows as a weed in commercial nurseries in several centres and is commonly naturalized in the Southern Tablelands of New South Wales, in eastern Victoria, and in Tasmania; mostly in tableland areas, to c. 1 700 m elevation. In New Zealand, it occurs throughout the North and South islands and Stewart Island; from sea level to 900 m elevation (once collected at 1 400 m on Maungapohatu). One plant was collected on Campbell Island in 1961, two small but apparently healthy plants about three-quarters of a mile away in 1970; both were in prepared garden soil. The introduction and spread of this species in Australasia were discussed on pp. 63-4.
Habit: Erect perennial herb (3-)10-120(-190) cm tall, well-branched or simple, perennating from leafy basal rosettes or large fleshy condensed underground shoots; stems terete, often thick, light-colored to reddish, covered on at least the apical portion with short subappressed eglandular and /or gland-tipped hairs, with raised lines of strigulose hairs decurrent from the margins of the petioles, or the whole plant covered with dense sericeous pubescence.
Leaves: Leaves basal and cauline, (0.5-) 3-12 (-12) cm long, (0.2-) 0.6-5.5 cm wide, at least lower cauline leaves opposite, very narrowly lanceolate or ovate to elliptic, basal leaves commonly obovate, subglabrous except for strigillose margins, or sometimes densely strigillose throughout, serrulate, with 15-40 irregular teeth on each side, lateral veins conspicuous, 4-10 on each side of midrib, base obtuse to abruptly rounded, apex subacute to acuminate, serrulate, mostly longer than internodes they subtend, petiole 0-0.5 (-1) cm long.
Flowers: Inflorescence nodding. Flowers erect, ovaries covered with a mixture of strigulose and glandular hairs, 8-40 mm long, on pedicles 2-14 mm long, floral tube 0,5-2.6 mm deep, 0.9-3.5 mm across, a ring of long villous hair inside, sepals often reddish, 2-7.5 mm long, 0.7-2.5 mm wide, sometimes keeled, strigulose and glandular pubescent, petals white to rose purple, 2-14 mm long, 1.3-6.3 mm wide, the notch 0.4-2.5 mm deep, staminal filaments white or cream to purple, those of the longer stamens 1.4-7 mm long, those of shorter ones 0.6-5.2 mm long, anthers cream or yellow to white, 0.4-1.8 mm long, 0.26-0.9 mm wide, those of at least the longer stamens often shedding pollen directly onto the stigma, style cream to yellow, 1.1-8.5 mm long, stigma cream to orange-yellow, narrowly to broadly clavate or subcapitate, 0.8-2.8 mm long. 0.4-1.2 mm across, rarely exerted beyond the anthers.
Fruit: Capsule loculicidal, (15-) 30-100 mm long, 1.1-2.5 mm in diameter, strigulose and glandular-pubescent, on pedicels 2-15 (-40) mm long, rarely subsessile.
Seeds: Seeds many, in 1 row per locule, (0.6-)0.8-1.6(-1.9) mm long, (0.26-)0.3-0.64 mm wide, narrowly obovoid, the chalazal collar pellucid, 0.02-0.32 long, 0.08-0.38 in diameter, grey-brown, the abaxial surface marked with conspicuous parallel longitudinal ridges of laterally flattened papillae, tuft of hairs white, 6-7 mm long.
Chromosomes: Gametic chromosome number: n = 18.
Notes: FNA, Flowers November to March, occasionally in other months in protected sites.