Erysimum
Sp. Pl. 2: 660. 1753.
Gen. Pl. ed. 5, 296. 1754.
Plants not scapose; pubescent, trichomes sessile, medifixed, appressed, 2-rayed (malpighiaceous) or 3–5(–8)-rayed (stellate), rays (when 2) parallel to long axis of stems, leaves, sepals, and fruits. Stems erect or ascending [decumbent], unbranched or branched basally and/or distally. Leaves basal and cauline; petiolate or sessile; basal rosulate or not, petiolate, blade margins usually entire, dentate, sinuate-dentate, or denticulate, rarely pinnatifid or pinnatisect; cauline petiolate or sessile, blade (base cuneate or attenuate [auriculate]), margins entire, dentate, denticulate, dentate-sinuate, or repand. Racemes (densely flowered, E. pallasii bracteate basally). Fruiting pedicels erect, ascending, divaricate, reflexed, horizontal, or spreading, slender or stout (nearly as wide as fruit). Flowers: sepals oblong or linear, lateral pair saccate or not basally (pubescent); petals suborbicular, obovate, or spatulate, claw differentiated from blade (subequaling or longer than sepals, apex rounded [emarginate]); stamens (erect), tetradynamous; filaments not dilated basally; anthers oblong or linear; nectar glands (1, 2, or 4), distinct or confluent, subtending bases of stamens, median glands present or absent. Fruits usually sessile, rarely shortly stipitate (gynophore to 4 mm), usually linear or narrowly so [oblong], smooth or torulose, (keeled or not); valves each with obscure to prominent midvein, pubescent outside, usually glabrous inside; replum rounded; septum complete, (not veined); ovules [15–]20–120 per ovary; (style relatively short, rarely 1/2 as long as or subequaling fruit, often pubescent); stigma capitate. Seeds plump or flattened, winged, margined, or not winged, oblong, ovoid, obovate, or suborbicular; seed coat (minutely reticulate), mucilaginous when wetted; cotyledons incumbent, rarely accumbent. x = (6) 7, 8 (9–17).
Distribution
North America, n Mexico, Central America, Europe, Asia, n Africa, Atlantic Islands (Macaronesia), introduced in South America, Australia.
Discussion
Species ca. 150 (19 in the flora).
Erysimum is found in the northern hemisphere, primarily Asia and Europe, with eight species in northern Africa and Macaronesia, and one each endemic to Baja California (E. moranii Rollins) and Costa Rica and Guatemala (E. ghiesbreghtii J. D. Smith). Of the 21 species found in North America, four are naturalized. Most of the native species have x = 9 and are believed to represent a monophyletic group (R. A. Price 1987).
Erysimum is a taxonomically difficult genus much in need of comprehensive phylogenetic and systematic studies covering its entire range. The principal sources of difficulty are the inflation in the number of species described, the heavy reliance on vegetative morphological characters in the delimitation of species, and the inadequacy of most herbarium specimens. In order to reliably identify a given sample, one often needs a complete specimen that has basal leaves, flowers, mature fruits, and seeds. Unfortunately, plants of most species shed their basal leaves or have no flowers when at full fruit maturity. Another complicating factor in North America is that almost all of the native species readily hybridize in areas of overlap to produce wide arrays of intermediates that backcross with the parents and blur species boundaries.
Selected References
Lower Taxa
Key
| 1 | Petals 3-10(-15) × 1.5-3 mm; median filaments 2-7(-10) mm | > 2 |
| 1 | Petals (10-)13-30(-35) × 3-10(-15) mm; median filaments (6-)7-15 mm | > 6 |
| 2 | Fruit valves densely pubescent inside; sepals 1.8-3.2 mm; petal claws 1.5-3.5 mm. | Erysimum cheiranthoides |
| 2 | Fruit valves usually glabrous inside, rarely sparsely pubescent; sepals 4-7(-8) mm; petal claws 3-8 mm | > 3 |
| 3 | Annuals; fruiting pedicels as wide as fruit. | Erysimum repandum |
| 3 | Biennials or perennials (short-lived); fruiting pedicels narrower than fruit | > 4 |
| 4 | Stigmas entire; fruits appressed to rachises; leaf blade surfaces and fruit valves with 3- and 4-rayed trichomes. | Erysimum hieraciifolium |
| 4 | Stigmas strongly 2-lobed; fruits not appressed or subappressed to rachises; leaf blade surfaces and fruit valves with 2- or 3-rayed trichomes | > 5 |
| 5 | Petals narrowly obovate to spatulate, (8-)10-15 × (2-)2.5-4 mm; fruits 1.8-2.5 mm wide; seeds 1.5-2 mm. | Erysimum coarctatum |
| 5 | Petals oblanceolate, 6-9(-11) × 1-2 mm; fruits 1.2-1.7 mm wide; seeds 1.2-1.7 × 0.8-1 mm. | Erysimum inconspicuum |
| 6 | Subshrubs (stems woody at base) | > 7 |
| 6 | Biennials or perennials (stems not woody at base) | > 10 |
| 7 | Fruit valve trichomes 2-rayed; stigmas strongly 2-lobed, lobes much longer than wide; petals orange, yellow, brown, red, purple, violet, or white. | Erysimum cheiri |
| 7 | Fruit valve trichomes 2-4-rayed; stigmas not strongly 2-lobed, lobes as long as wide; petals yellow or cream | > 8 |
| 8 | Fruits angustiseptate; leaf trichomes 2- or 3-rayed. | Erysimum insulare |
| 8 | Fruits latispetate or 4-angled; leaf trichomes 2-5-rayed | > 9 |
| 9 | Distal cauline leaves petiolate; fruits latiseptate, not 4-angled; fruiting pedicels stout, 5-17(-22) mm. | Erysimum franciscanum |
| 9 | Distal cauline leaves sessile; fruits slightly latiseptate or 4-angled; fruiting pedicels slender, (3-)5-10 mm. | Erysimum suffrutescens |
| 10 | Petals purple or lilac; leaf trichomes 2-rayed; sepals 5-9 mm; anthers 1-1.5 mm. | Erysimum pallasii |
| 10 | Petals usually yellow or orange, rarely lavender or purplish; leaf trichomes (at least some) 3-7-rayed; sepals 7-14 mm; anthers 2-4 mm | > 11 |
| 11 | Basal leaf blades filiform to narrowly linear, (somewhat revolute, appearing terete). | Erysimum teretifolium |
| 11 | Basal leaf blades not filiform or narrowly linear | > 12 |
| 12 | Fruits 4-angled, longitudinally 4-striped; valves densely pubescent between midvein and replum with 2-rayed trichomes; ovules 72-120 per ovary. | Erysimum asperum |
| 12 | Fruits latiseptate, rarely 4-angled, not longitudinally striped; valves pubescent with 2-6-rayed trichomes; ovules 24-86 per ovary | > 13 |
| 13 | Leaf blades: surfaces with 2 (or 3)-rayed trichomes | > 14 |
| 13 | Leaf blades: surfaces with 2-5(-7)-rayed trichomes | > 16 |
| 14 | Fruits usually 4-angled, rarely latiseptate; ovules (40-)54-82 per ovary; seeds not winged, 1.5-2(-2.4) mm. | Erysimum capitatum |
| 14 | Fruits strongly latiseptate; ovules 24-46 per ovary; seeds usually broadly winged all around or apically, rarely not winged, 2-3.5 mm | > 15 |
| 15 | Perennials; seeds not winged or winged distally; fruits 1.5-2.7 mm wide. | Erysimum arenicola |
| 15 | Biennials; seeds winged all around; fruits (2-)2.4-3.7 mm wide. | Erysimum occidentale |
| 16 | Fruits torulose; ovules 26-44 per ovary; petals 3.5-6 mm wide. | Erysimum perenne |
| 16 | Fruits not torulose; ovules (32-)42-86 per ovary; petals (5-)6-16 mm wide | > 17 |
| 17 | Fruiting pedicels 2-4(-6) mm; seeds broadly obovate to suborbicular, 1.5-3 mm wide. | Erysimum concinnum |
| 17 | Fruiting pedicels 4-17(-25) mm; seeds oblong, 1-2 mm wide | > 18 |
| 18 | Fruits divaricate, ascending, or erect; petals orange or orange-yellow to yellow; seeds winged distally; Midwestern, Mountain, Pacific states. | Erysimum capitatum |
| 18 | Fruits spreading; petals yellow; seeds winged all around; California (Humboldt, Mendocino, Monterrey, Santa Cruz counties) | > 19 |
| 19 | Basal leaf blades linear-oblanceolate, 2-9 mm wide; stems 0.4-9(-13) dm; fruit valves each with prominent midvein; ovules 50-86 per ovary. | Erysimum ammophilum |
| 19 | Basal leaf blades spatulate, 5-15 mm wide; stems 0.2-2.5(-3.5) dm; fruit valves each with obscure midvein; ovules 32-74 per ovary. | Erysimum menziesii |