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Perideridia howellii

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: PerideridiaView DescriptionDichotomous Key

Common Name: YAMPAH
Habit: Perennial herb, glabrous, generally glaucous; roots tuberous, single or clustered, or clustered-fibrous. Stem: erect, branched. Leaf: blade lanceolate to triangular-ovate, generally 1--2-ternate-pinnate or 1--2-pinnately or ternate-pinnately dissected, leaflets or segments generally linear to lance-linear. Inflorescence: umbels compound; bracts 0--many, conspicuous and reflexed or not; bractlets several to many, narrow, +- scarious; rays, pedicels few to many, generally spreading-ascending; 2° umbels generally convex distally. Flower: calyx lobes evident; petals generally obovate, white, tips narrowed. Fruit: linear-oblong, +- compressed side-to-side or not at all, glabrous; ribs +- equal, thread-like to prominent, not winged; oil tubes 1--several per rib-interval; fruit axis divided to base. Seed: face flat to grooved.
Species In Genus: +- 12 species: generally western America. Etymology: (Greek: around the neck, from involucre) Note: Roots, basal leaves needed for identification.

Perideridia howellii (J.M. Coult. & Rose) Mathias
Habit: Plant 8--16 dm; roots fibrous, +- thickened, > 15-clustered, 4--15 cm. Leaf: basal petiole 10--20 cm; basal blade 30--50 cm, +- lanceolate, 2-pinnate, leaflets 2--7 cm, 1--4 cm wide, +- ovate, deeply toothed or lobed; cauline leaves like basal. Inflorescence: peduncle 5--25 cm; bracts 8--12, 0.5--2 cm, linear-spoon-shaped, scarious-margined, reflexed; bractlets +- 10, 5--12 mm, lanceolate; rays generally 17--20, 2--7 cm, generally +- equal, spreading-ascending; pedicels 5--15 mm; 2° umbels 25--30-flowered. Flower: calyx lobes prominent; petals 5--7-veined; styles < 0.5 mm. Fruit: 4--6 mm, oblong; ribs conspicuously corky; oil tube 1 per rib-interval. Chromosomes: 2n=40.
Ecology: Moist meadows, ravines, streambanks; Elevation: 100--1500 m. Bioregional Distribution: KR, NCoRO, CaR, n SN, c SNF; Distribution Outside California: Oregon. Flowering Time: Jul--Aug
eFlora Treatment Author: Lincoln Constance & Margriet Wetherwax
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botanical illustration including Perideridia howellii


Citation for this treatment: Lincoln Constance & Margriet Wetherwax 2016. Perideridia howellii, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on April 30, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora,, accessed on April 30, 2016.

Perideridia howellii
click for enlargement
© 2010 Barry Breckling
Perideridia howellii
click for enlargement
© 2010 Barry Breckling
Perideridia howellii
click for enlargement
© 2010 Barry Breckling
Perideridia howellii
click for enlargement
© 2010 Barry Breckling

More photos of Perideridia howellii in CalPhotos

Geographic subdivisions for Perideridia howellii:
KR, NCoRO, CaR, n SN, c SNF;
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.