Elymus is a genus of perennial plants with approximately 150 species in the grass family, related to rye, wheat, and other widely grown cereal grains.
Elymus scribneri is a species of wild rye known by the common names spreading wheatgrass and Scribner's wheatgrass.
 It is native to much of the western United States and parts of central Canada where it grows in several types of habitat including alpine mountain peaks.
Elymus canadensis is a species of wild rye known by the common name Canada wild rye.
 This grass is native to much of North America, being most abundant in the central plains and Great Plains.
 It grows in a number of ecosystems, including riparian woodlands, many types of forest, lakeside sand dunes, and tallgrass prairie.
Nicandra is a monotypic genus of flowering plants in the nightshade family containing the single species Nicandra physalodes.
 It is known by the common names apple-of-Peru and shoo-fly plant.
 It is thought originally to have been native to Peru (known elsewhere as an introduced species and sometimes as a weed) and is found nowadays as a ruderal species in tropical, subtropical and, to a lesser extent, temperate areas all over the world.
 It has also long been cultivated as an ornamental plant for its attractive flowers and curious fruits (the latter sometimes dried for use in floral design) and has been adopted into the traditional medicine of countries far-removed from its original home.

Question: Elymus and Nicandra, are types of what?
Answer: plants