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Heracleum maximum

Higher Taxonomy
Family: Apiaceae (Umbelliferae)View DescriptionDichotomous Key

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
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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botanical illustration including Heracleum maximum


Citation for this treatment: Lincoln Constance & Margriet Wetherwax 2016. Heracleum maximum, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on May 01, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora,, accessed on May 01, 2016.

Heracleum maximum
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© 2014 Steve Matson
Heracleum maximum
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© 2008 Keir Morse
Heracleum maximum
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© 2010 Keir Morse
Heracleum maximum
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© 2010 Steve Matson
Heracleum maximum
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© 2008 Neal Kramer
Heracleum maximum
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© 2015 Barry Breckling

More photos of Heracleum maximum in CalPhotos

Geographic subdivisions for Heracleum maximum:
Markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
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.