38. Armoracia P. Gaertner, B. Meyer & Scherbius, Oekon. Fl. Wetterau. 2: 426. 1800.
[name conserved]
Horseradish [Ancient Greek name for horseradish, or perhaps Celtic ar, near, mor, sea, and rich, against, alluding to habitat]
Ihsan A. Al-Shehbaz
Perennials; (aquatic or of mesic habitats, with rootstocks); not scapose; glabrous. Stems erect, branched distally. Leaves basal and cauline; petiolate and sessile; basal rosulate, long-petiolate, blade margins crenate or pinnatifid [entire]; cauline petiolate or sessile distally, blade margins crenate, serrate, pinnatifid, pinnatisect [laciniate]. Racemes ([often corymbose-paniculate], several-flowered), considerably elongated in fruit. Fruiting pedicels ascending, divaricate, or slightly reflexed, slender. Flowers: sepals spreading or ascending, ovate or oblong, lateral pair not saccate basally, (glabrous); petals white, obovate, or oblanceolate [spatulate, oblong], claw somewhat differentiated from blade (relatively short, apex obtuse); stamens slightly tetradynamous; filaments slightly dilated basally; anthers ovate [oblong or linear], (apex obtuse); nectar glands confluent, subtending bases of stamens, median glands present. Fruits: silicles, sessile, oblong, ovate, elliptic, or orbicular, angustiseptate; valves each not veined; replum rounded; septum perforated or reduced to a rim; ovules 8-12[-20] per ovary; style obsolete or distinct; stigma capitate, (sometimes 2-lobed). Seeds biseriate, plump, not winged, ovate [oblong]; seed coat (punctate) not mucilaginous when wetted; cotyledons accumbent.
Species 3 (1 in the flora): introduced; c, s Europe, Asia (Russian Far East, Siberia).
SELECTED REFERENCES Fosberg, F. R. 1965. Nomenclature of the horseradish (Cruciferae). Baileya 13: 1-4. Lawrence, G. H. M. 1971. The horseradish Armoracia rusticana. Herbarist 37: 17-19.
