Fig 203. [Marsh Elder. Iva xanthiifolia] (Fresen.) Nutt.

Marsh Elder. Iva xanthiifolia (Fresen.) Nutt. Achenes various shades of brown to black, flattened or rhombic in section, obovoid, 1.5–2 mm. long, longitudinally, striate with fine lines. Native to the upper peninsula of Michigan where it most likely was at one time introduced from the west. It has not been found in the lower peninsula, probably because it had no means of coming across Lake Michigan.

Fig 204. [Wild Lettuce. Lactuca Canadensis] L.

Wild Lettuce. Lactuca Canadensis L. Flowers yellow; achenes black or nearly so, flattened, oval, bearing 3 ribs, the lateral ones sometimes double, the middle one slender, surface abounding in minute transverse ridges as seen under a lens, the remains of a beak sometimes remaining. Native of this country. Other species of Lettuce are more or less troublesome.

Fig 205.[Prickly Lettuce. Lactuca virosa] L.