7. Lepidium latifolium L. (perennial pepper grass, broad-leaved pepper grass)

Pl. 323 g–i; Map 1366

Plants perennial herbs, with rhizomes. Stems (20–)35–120(–150) cm long, erect or ascending, mostly unbranched below the inflorescence, glabrous or nearly so. Leaves 1–30 cm long, linear to oblanceolate or elliptic in outline, the base not clasping, glabrous, the margins entire to finely toothed, the lower and middle ones petiolate, the upper leaves progressively reduced and sessile. Sepals 0.8–1.5 mm long, broadly elliptic to ovate. Petals 1.5–2.5 mm long, white. Stamens 6. Styles absent. Fruits 1.8–2.2(–2.7) mm long, broadly ovate to nearly circular in outline, the tip rounded, not notched or winged, flattened, sparsely hairy or glabrous. Seeds (0.8–)1.0–1.3 mm long, oblong-elliptic in outline, not winged, the surface with a very fine, netlike or honeycomb-like pattern of ridges and pits, brownish orange. 2n=24, 48. June–August.

Introduced, known only from a single collection from Jackson County (native of Europe and Asia, widely naturalized in the U.S. and adjacent Canada). Railroads.

This species was first collected in Missouri in 1975 from an area between a road and a railroad in the Kansas City area (Henderson, 1980). Its distribution in the United States is sporadic, but it may be expected to appear along other railroads in Missouri in the future.