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rayless arnica

Scientific Name: Arnica discoidea

Family: Asteraceae

Category: Dicot

Growth: Forb/herb

Duration: Perennial

Other Names:

       

Arnica discoidea: Rayless Arnica

Arnica discoidea, commonly known as rayless arnica, is a North American species belonging to the sunflower family (Asteraceae).

Taxonomy and Nomenclature

  • Scientific Name: Arnica discoidea Benth.
  • Family: Asteraceae (Sunflower family)
  • Synonyms:
    • Arnica discoidea var. eradiata (A. Gray) Cronquist
    • Arnica grayi
    • Arnica parviflora
    • Arnica parviflora ssp. alata
    • Arnica alata Rydberg
    • A. cordifolia Hooker var. eradiata A. Gray
    • A. discoidea var. alata
  • Related Species and Hybrids: Arnica x diversifolia Greene (pro sp.) amplexicaulis or mollis cordifolia or latifolia.

Distribution and Habitat

  • Native to the western United States, specifically California, and also found outside of California.
  • Grows in woodlands, forests, and chaparral.
  • Generally found at medium-to-high montane elevations, but rarely reaches the alpine zone.

Morphological Characteristics and Growth Habits

  • Arnica discoidea is a perennial herb.
  • Arnica diversifolia is a perennial growing to 0.3 m (1ft).

Distinguishing Features

  • The key characteristic of rayless arnica is the lack of ray (ligulate) flowers in its flower heads, hence the common name.
  • A similar species, Arnica parryi, also known as rayless arnica, has narrower leaves and nodding heads when in bud.

Ecological Role

  • The flowers of Arnica diversifolia are hermaphrodite (have both male and female organs) and are pollinated by Apomictic

Further Information

  • Oregon Flora Project: Provides information and images of Arnica discoidea.
  • Discover Life: Offers details about the biology, natural history, ecology, identification, and distribution of rayless arnica.