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Heracleum maximum
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Cow Parsnip
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Heracleum maximum

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About Cow Parsnip (Heracleum maximum) Cow Parsnip (Heracleum maximum) is a member of the Apiaceae (Carrot) family and the only member of this genus native to North America. Cow Parsnip is distributed throughout the continental United States and Alaska except the Gulf Coast and a few neighboring states. It is the only native member of this family to occur throughout the U.S. In California it occurs primarily in the northern half of the state. It is relatively large for an herb and features a large flower head consisting of the typical flat-topped umbels of the Carrot family. Chemicals in the plant may cause dermatitis in some individuals. It may be weedy or invasive in portions of its range.
Plant Description
Plant Type
Perennial herb

Max. Height
4 - 8 ft (1.2 - 2.4 m)


Growth Rate

Flower Color

Flowering Season

Native Status

Natural Setting
Site Type
Meadows, moist places, wooded or open

Part Shade

Elevation ?
6' - 10562'

Annual Precip. ?
11.3" - 131.3"

Summer Precip. ?
0.23" - 4.41"

Coldest Month ?
23.1° F - 52.0° F

Hottest Month ?
47.6° F - 79.3° F

Humidity ?
0.12 vpd - 21.76 vpd

Soil Description
Tolerant of a variety of soils as long as sufficient moisture is provided

Soil PH
5.2 - 6.7

Fast, Medium, Slow

Cold Tolerance(° F)
Tolerates cold to -10° F

Sunset Zones ?
4*, 5*, 6, 7, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

Landscaping Information
Ease of Care
Very Easy

Water Requirement ?
Extremely Low
Very Low
Moderate - High

Seldom Used

Common uses
Deer Resistant, Butterfly Gardens, Butterfly Gardens

Nursery Availability
Commonly Available

Other Names
Botanical Names
Heracleum lanatum

Common Names
Common Cowparsnip

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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