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Rayless Arnica
Arnica discoidea
About Rayless Arnica (Arnica discoidea) 0 Nurseries Carry This Plant Arnica discoidea is a species of arnica known by the common name rayless arnica. It is native to the woodlands, forests, and chaparral of the western United States. This is a rhizomatous perennial herb producing a hairy, hairy stem 20 to 60 centimeters tall. There are several pairs of toothed oval to spade-shaped leaves on long petioles around the lower half of the stem. The flower cluster contains a few to many flower heads which are coated with hairy hairs. Each head contains only disc florets, but some of the florets around the edge can be expanded and resemble ray florets, making identification of the plant by its flower difficult. The fruit is an achene about 7 millimeters long, not counting its light-colored pappus.
Plant Description
Plant Type
Plant Type
Perennial herb

0.7 - 2 ft tall

Flower Color
Flower Color

Landscaping Information
Part Shade

Sunset Zones
Sunset Zones?
1, 2, 3, 6, 7, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

Natural Setting
Annual Precipitation: 13.1" - 151.6", Summer Precipitation: 0.21" - 5.67", Coldest Month: 10.8" - 54.2", Hottest Month: 34.1" - 79.3", Humidity: 0.08" - 25.02", Elevation: 22" - 14090"

Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links:   Jepson eFlora Taxon Page  CalPhotos  Wikipedia  Calflora

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