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    Vascular Plants of California
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Armoracia rusticana

Higher Taxonomy
Family: Brassicaceae (Cruciferae)View DescriptionDichotomous Key

Habit: Annual to shrub; sap pungent, watery. Leaf: generally simple, alternate; generally both basal, cauline; stipules 0. Inflorescence: generally raceme, generally not bracted. Flower: bisexual, generally radial; sepals 4, generally free; petals (0)4, forming a cross, generally white or yellow to purple; stamens generally 6 (2 or 4), 4 long, 2 short (3 pairs of unequal length); ovary 1, superior, generally 2-chambered with septum connecting 2 parietal placentas; style 1, stigma entire or 2-lobed. Fruit: capsule, generally 2-valved, "silique" (length >= 3 × width) or "silicle" (length < 3 × width), dehiscent by 2 valves or indehiscent, cylindric or flat parallel or perpendicular to septum, segmented or not. Seed: 1--many, in 1 or 2 rows per chamber, winged or wingless; embryo strongly curved.
Genera In Family: +- 330 genera, 3780 species: worldwide, especially temperate. Note: Highest diversity in Mediterranean area, mountains of southwestern Asia, adjacent central Asia, western North America; some Brassica species are oil or vegetable crops; Arabidopsis thaliana used in experimental molecular biology; many species are ornamentals, weeds. Aurinia saxatilis (L.) Desvaux in cultivation only. Aubrieta occasional waif in central NCoR, Carrichtera annua (L.) DC. in SCo, Iberis sempervirens L., Iberis umbellata L. in PR, Teesdalia coronopifolia (Bergeret) Thell., Teesdalia nudicaulis (L.) W.T. Aiton in southern NCoRO, CCo. Cardaria, Coronopus moved to Lepidium; Caulostramina to Hesperidanthus; Guillenia to Caulanthus; Heterodraba to Athysanus; California taxa of Lesquerella to Physaria; Malcolmia africana to Strigosella.
eFlora Treatment Author: Ihsan A. Al-Shehbaz, except as noted
Scientific Editor: Douglas H. Goldman, Bruce G. Baldwin.
Genus: ArmoraciaView Description 

Habit: Perennial herb, glabrous; roots fleshy. Leaf: basal long petioled, simple, entire or crenate; cauline entire to pinnately lobed, generally not basally lobed. Inflorescence: panicle. Flower: sepal spreading to ascending, base not sac-like; petals short-clawed, white. Fruit: silicle, dehiscent, unsegmented, ovate to oblong or +- round, flat perpendicular to septum; stigma entire or +- 2-lobed. Seed: in 2 rows per chamber; wing 0.
Species In Genus: 3 species: Eurasia. Etymology: (Greek: horse radish)
eFlora Treatment Author: Ihsan A. Al-Shehbaz

Armoracia rusticana G. Gaertn., B. Mey., & Scherb.
Habit: Generally erect; roots deep. Stem: branched distally, 5--12(20) dm. Leaf: basal 1.5--12 dm, wide-oblong to ovate, crenate; proximal cauline petioled, distal sessile, pinnately lobed or occasionally entire. Flower: sepals 2--4 mm; petals obovate, 5--7(8) mm. Fruit: 4--6 mm, generally aborted; style <= 0.5 mm; pedicel ascending, 0.8--2 cm. Seed: 8--12, ovate; rare. Chromosomes: 2n=32.
Ecology: Ditches, roadsides, moist places, fields; Elevation: < 1100 m. Bioregional Distribution: GV, CCo, SnFrB; Distribution Outside California: temperate North America; native to Eurasia. Flowering Time: Mar--Jul Note: Cult over 2000 years for roots.
eFlora Treatment Author: Ihsan A. Al-Shehbaz
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botanical illustration including Armoracia rusticana


Citation for this treatment: Ihsan A. Al-Shehbaz 2012, Armoracia rusticana, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on October 19, 2018.

Citation for the whole project: Jepson Flora Project (eds.) 2018, Jepson eFlora,, accessed on October 19, 2018.

Geographic subdivisions for Armoracia rusticana:
GV, CCo, SnFrB;
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.
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, if there are more than 1 infraspecific taxon in CA.
Blue line denotes eFlora flowering time.