Longflower tobacco

Nicotiana acuta Grisebach; N. acutiflora A. Saint-Hilaire

Herbs, annual or biennial, from basal rosette. Stems single or with few spreading lateral branches, 5–8(–10) dm, sparsely pubescent, usually not viscid, tuberculate. Rosette leaves sessile; blade elliptic to oblan­ceolate, 10–30(–50) cm, base narrowed and winged, surfaces coarsely viscid-pubescent. Cauline leaves ses­sile; blade ovate to lanceolate or linear, 1–5 cm, progressively smaller and more linear towards inflo­rescence, base auriculate, apex acute to attenuate, surfaces coarsely viscid-pubescent. Inflorescences false racemes, occasionally with few weak branches, not leafy; flowering crepuscular. Pedicels 0.5–1.3 cm. Flowers: calyx green or occasionally somewhat pur­plish-tinged, 1.5–2.5 cm, tube elliptic, 10-ribbed, sinus membranes long and transparent, minutely pubescent, sometimes viscid, lobes usually spreading, subulate, ± equal, equaling tube; corolla straight, 4–12 cm (excluding limb), puberulent externally, tube and throat not well differentiated, straight, white or often grayish white, 2 mm diam. at base, gradually widening and somewhat broader in distal 1/4, abruptly swollen to 6 mm diam. just below constricted mouth, glabrous or minutely puberulent internally, limb spreading, sometimes with purplish-gray veins abaxially, adaxially white or ivory, stellate, 2–5 cm diam., lobes triangular to deltate, acute; stamens inserted in upper part of tube just below mouth, included; filaments unequal, free for at least some of their length (anthers not sessile),four 0.1–0.8 cm (2 of these slightly longer), 1 shorter, ca. 0.1 cm, glabrous; style straight, just exceeding stamens, exserted from corolla mouth. Capsules ovoid, 1.1–1.6 cm. Fruiting calyces not tearing at scarious sinuses, nearly covering capsule, lobe tips spreading. Seeds 0.5 mm. 2n = 20.

Flowering Apr–Aug. Open fields, stream banks, wet places, ballast sites near ports; 0–200 m; introduced; Ont., Que.; Ala., Fla., Ga., Ill., Ind., La., Mass., Miss., Mo., Tex., W.Va.; South America (Argentina, Bolivia, Paraguay); introduced also in Europe (Germany, Sweden), Africa (South Africa).

Nicotiana longiflora is a relatively rare weed along rivers and in waste places. It could be confused with N. plumbaginifolia, with which it is sympatric along the Gulf Coast, but differs from that species in its much larger flowers and its strongly 10-ribbed calyx. In a vegetative state, the two species are very difficult to distinguish.