Arnica chamissonis, the Chamisso arnica, is a North American species of plants in the sunflower family.
 It is very similar to "Arnica montana".
 "Arnica chamissonis" is native to the United States and Canada and naturalized in parts of Europe while "A. montana" is indigenous to Europe.
Arnica longifolia is a North American species of arnica in the sunflower family, known by the common names seep-spring arnica, longleaf arnica and spearleaf arnica.
 This flowering perennial is native to the forests of western Canada (British Columbia + Alberta) and the western United States (Rocky Mountains, Cascades, Coast Ranges, Sierra Nevada and other mountains of California, Oregon, Washington, Idaho, Nevada, Utah, Wyoming, Colorado, and Montana).
Arnica rydbergii is a North American species of arnica in the sunflower family, known by the common name Rydberg’s arnica or subalpine arnica or subalpine leopardbane.
 It is native to western Canada (Alberta, British Columbia), and the western United States (Alaska, Washington, Oregon, Utah, Idaho, Montana, Utah, Wyoming, Colorado, South Dakota).
Arnica latifolia is a species of arnica in the sunflower family, known by the common names broadleaf arnica, broad leaved arnica, mountain arnica, and daffodil leopardbane.
 It is native to western North America from Alaska east to Northwest Territories and south to Mono County, California and Taos County, New Mexico.
 It grows in mountain habitat such as forest and meadows.
Arnica venosa is an rare California species of arnica in the sunflower family known by the common name Shasta County arnica.
 It should not be confused with the Mt. Shasta arnica, "A. viscosa."
Nothoscordum is a genus of New World plants in the onion tribe within the Amaryllis family.
 It is probably paraphyletic.
 The genus is native to North and South America, though a few species have become naturalized in various parts of the Old World.
Arnica mollis is a North American species of arnica in the sunflower family, known by the common name soft arnica, or hairy arnica.
 It is native to Canada (British Columbia, Alberta, Quebec, and all 3 Arctic territories) and the United States (Alaska and the western mountains as far south as San Bernardino County, California and Rio Arriba County, New Mexico.
 There are also isolated populations in the White Mountains of Coos County, New Hampshire.
 The species grows in subalpine mountain habitat such as meadows and streambanks.
Arnica nevadensis is a North American species of arnica in the sunflower family, known by the common names Nevada arnica and Sierra arnica.
 It is native to the coniferous forests of the western United States, primarily the Cascades and Sierra Nevada (Washington, Oregon, California, Nevada).
Arnica is a genus of perennial, herbaceous plants in the sunflower family (Asteraceae).
 The genus name "Arnica" may be derived from the Greek "arni", "lamb", in reference to the plants' soft, hairy leaves.
 "Arnica" is also known by the names "Mountain Tobacco" and, confusingly, "Leopard's bane" and "Wolfsbane"—two names that it shares with the entirely unrelated genus "Aconitum".
Arnica viscosa is an uncommon North American species of arnica in the sunflower family, known by the common name Mount Shasta arnica (not to be confused with the Shasta County arnica, A. venosa).

Question: Are Arnica and Nothoscordum both from the sunflower family?
Answer: no