22. Diplotaxis de Candolle, Mém. Mus. Hist. Nat. 7: 243. 1821.
Wall-rocket [Greek diplo-, double, and taxis, arrangement, alluding to number of seed rows in each locule of fruit]
Juan B. Martínez-Laborde
Annuals, biennials, or perennials; (sometimes suffrutescent); scapose or not; glabrous, glabrescent, or pubescent. Stems erect or ascending, branched. Leaves basal and, sometimes, cauline; petiolate or sessile; basal rosulate or not, petiolate, blade margins dentate, sinuate, or pinnatisect; cauline petiolate or sessile, blade (base not auriculate), margins entire or dentate. Racemes (corymbose, sometimes shortly bracteate basally), considerably elongated in fruit. Fruiting pedicels ascending, divaricate, or reflexed, stout to slender. Flowers: sepals ascending to spreading, oblong, lateral pair not saccate basally; petals yellow or white [purple], obovate, (apex rounded or truncate); stamens tetradynamous; filaments not dilated basally; anthers oblong to ovate, (apex obtuse); nectar glands (4): lateral cushionlike, median cylindrical. Fruits siliques, dehiscent, sessile or (long-)stipitate, segments 1 or 2, linear to linear-oblong, torulose, latiseptate or terete; (proximal segment numerous-seeded, 1-veined; terminal segment 0-2-seeded); valves glabrous; replum rounded; septum complete; ovules [12-]20-36(-46)[-276] per ovary; (style obsolete or distinct); stigma capitate or somewhat decurrent, 2-lobed. Seeds usually biseriate, rarely uniseriate, not winged, ovoid or ellipsoid; seed coat (smooth or minutely reticulate), slightly mucilaginous or not when wetted; cotyledons conduplicate. x = 7, [8, 9, 10,] 11, [13,] 21.
Species 25-30 (3 in the flora): introduced; Europe, Asia, n Africa; introduced also in n Mexico, West Indies (Bahamas), Bermuda, South America, Pacific Islands (New Zealand), Australia.
SELECTED REFERENCES Eschmann-Grupe, G., H. Hurka, and B. Neuffer. 2003. Species relationships within Diplotaxis (Brassicaceae) and the phylogenetic origin of D. muralis. Pl. Syst. Evol. 243: 13-29. Martínez-Laborde, J. B. 1988. Estudio Sistemático del Género Diplotaxis DC. (Cruciferae, Brassiceae). Ph.D. dissertation. Universidad Politécnica de Madrid. Mummenhoff, K., G. Eschmann-Grupe, and K. Zunk. 1993. Subunit polypeptide composition of rubisco indicates Diplotaxis viminea as maternal parent species of amphidiploid Diplotaxis muralis. Phytochemistry 34: 429-431. Sánchez-Yélamo, M. D. and J. B. Martínez-Laborde. 1991. Chemotaxonomic approach to Diplotaxis muralis (Cruciferae, Brassiceae) and related species. Biochem. Syst. & Ecol. 19: 477-482.
