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Heracleum maximum
COW PARSNIP, GIANT HOGWEED

Higher Taxonomy
Family: Apiaceae (Umbelliferae)View DescriptionDichotomous Key

Common Name: CARROT FAMILY
Habit: Annual to perennial herb [shrub, tree], generally from taproot. Stem: generally +- scapose, generally ribbed, hollow. Leaf: basal and generally cauline, generally alternate; stipules generally 0; petiole base generally sheathing stem; blade generally much dissected, occasionally compound. Inflorescence: umbel or head, simple or compound, generally peduncled; bracts present in involucres or 0; bractlets generally present in "involucels". Flower: many, small, generally bisexual (or some staminate), generally radial (or outer bilateral); calyx 0 or lobes 5, small; petals 5, free, generally ovate or spoon-shaped, generally incurved at tips, generally +- ephemeral; stamens 5; pistil 1, ovary inferior, 2-chambered, generally with a +- conic, persistent projection or platform at tip subtending 2 free styles. Fruit: 2 dry, 1-seeded halves (= mericarps), separating from each other but generally +- persistent to central axis; ribs on halves 5, 2 marginal, 3 to back; oil tubes 1--several per interval between ribs.
Genera In Family: 300 genera, 3000 species: +- worldwide, especially temperate; many cultivated for food or spice (e.g., Carum, caraway; Daucus; Petroselinum); Bupleurum lancifolium Hornem. is historical garden weed; some toxic (e.g., Conium). Note: Mature fruit generally critical in identification, shape given in outline. Hydrocotyle moved to Araliaceae. Petroselinum crispum (Mill.) A.W. Hill is a waif.
eFlora Treatment Author: Lincoln Constance & Margriet Wetherwax, except as noted
Scientific Editor: Douglas H. Goldman, Bruce G. Baldwin.
Genus: HeracleumView Description 

Common Name: HOGWEED
Habit: Perennial herb from taproot or clustered roots. Stem: stout, erect, generally branched, hollow. Leaf: blades oblong to round, ternately, pinnately, or palmately compound (simple), leaflets large, lobed or serrate; distal-most cauline generally reduced to large sheaths. Inflorescence: umbels compound, large, margins generally sterile; bracts 0--few, generally deciduous; bractlets generally present, persistent; rays, pedicels many, spreading-ascending. Flower: marginal bilateral, outer petals > others, 2-lobed; calyx lobes generally 0; petals wide, white, +- yellow. Fruit: oblong-ovate to round or obcordate, compressed front-to-back; ribs unequal, marginal thin-winged, veined near outer margin, others thread-like; oil tubes 1--2 per rib-interval, unequal in length; fruit axis divided to base. Seed: face flat.
Species In Genus: +- 80 species: Eurasia, eastern Africa, 1 in North America. Etymology: (Hercules, presumably from large stature of some species)

Heracleum maximum W. Bartram
NATIVE
Habit: Plant 1--3 m, stout, tomentose, strong-scented. Leaf: round to reniform; petioles 1--4 dm, widely sheathing, distal sheaths enlarged, bladeless; blades 2--5 dm wide, ternate, leaflets 1--4 dm wide, ovate to round, cordate, lobed, coarsely serrate. Inflorescence: tomentose or long-hairy; peduncle 5--20 cm; rays 15--30, 5--10 cm, unequal; pedicels 8--20 mm. Flower: petals obovate, white. Fruit: 8--12 mm, obovate to obcordate, +- hairy. Chromosomes: 2n=22.
Ecology: Moist places, wooded or open; Elevation: < 2900 m. Bioregional Distribution: CA-FP, GB; Distribution Outside California: to Alaska, eastern United States, Arizona. Flowering Time: Apr--Jul Note: Only native Apiaceae sp. found from eastern to western North America.
Synonyms: Heracleum lanatum Michx.
Unabridged Note: Relationship to some Eurasian taxa unclear.
eFlora Treatment Author: Lincoln Constance & Margriet Wetherwax
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Citation for this treatment: Lincoln Constance & Margriet Wetherwax 2016. Heracleum maximum, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=27996, accessed on July 27, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on July 27, 2016.


Heracleum maximum
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© 2009 John Game
Heracleum maximum
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© 2009 Keir Morse
Heracleum maximum
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© 2009 John Game
Heracleum maximum
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© 2000 Gary A. Monroe
Heracleum maximum
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© 2009 Keir Morse
Heracleum maximum
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© 2014 Steve Matson

More photos of Heracleum maximum in CalPhotos


Geographic subdivisions for Heracleum maximum:
CA-FP, GB;
Markers link to CCH specimen records. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues. Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
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map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.