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Water Groundsel
Senecio hydrophilus
About Water Groundsel (Senecio hydrophilus) 1 Nurseries Carry This Plant Senecio hydrophilus is a species of flowering plant in the aster family known by the common names water ragwort and alkali-marsh ragwort. It is native to western North America from British Columbia to California to Colorado, where it grows in swampy places such as marshes. It can grow in standing water, including alkaline and salty water. It is a biennial or perennial herb producing a single erect stem or a cluster of a few stems which may exceed one meter in maximum height, at times approaching two meters. The stem is hollow, waxy in texture, and often pale green in color, and it emerges from a small caudex. The thick leaves are lance-shaped to oval with smooth or toothed edges, the blades up to 20 centimeters long and borne on petioles. Smaller leaves occur farther up the stem. The inflorescence is one or more large, spreading clusters of many flower heads. They contain many yellowish disc florets at the center and sometimes have small yellow ray florets as well.
Plant Description
Plant Type
Plant Type
Perennial herb

3.3 - 7 ft tall

Flower Color
Flower Color

Wildlife Supported

Landscaping Information
Part Shade


Soil Drainage
Soil Drainage

Natural Setting
Site Type
Site Type
Swamps, muddy places, standing saltwater

Annual Precipitation: 4.0" - 85.5", Summer Precipitation: 0.17" - 3.80", Coldest Month: 11.1" - 57.6", Hottest Month: 34.4" - 86.9", Humidity: 0.46" - 38.60", Elevation: -253" - 14034"

Alternative Names
Common Names: Alkali-marsh Ragwort, Water Ragwort

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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