Succulent annual herb 10 cm - 0.8 m tall Leaves: alternate, 7.5 - 12.5 cm long, lance-shaped to spatula-shaped, wavy-toothed to lobed. Flowers: pale lavender to yellowish white, 5 mm wide. Petals four. Stamens six. Fruit: a pod, 8 mm - 2 cm long, with a somewhat flattened beak. The pod is divided into two dissimilar joints: a small, cylindrical lower joint and a 3 - 9 mm wide, four-angled, egg-shaped or lance- egg-shaped upper joint (see Similar Species). The pods are corky when dry. Stems: upright to spreading, giving the plant a bushy appearance.
Similar species: When the upper joint of the pod is 3 - 5 mm wide, lance- egg-shaped and long-beaked, then the plant is referred to as Cakile edentula ssp. edentula var. lacustris. When the upper joint of the pod is 5 - 9 mm wide, egg-shaped and short-beaked, then the plant is referred to as C. edentula ssp. edentula var. edentula.
Flowering: June to late November
Habitat and ecology: A species of coastal sands. In the Chicago Region, this plant is usually found on the beaches of Lake Michigan. Here it is often at the forefront of beach vegetation in areas most subject to wave disturbance.
Occurence in the Chicago region: native
Etymology: Cakile is the old Arabic name for this plant. Edentula means toothless; without teeth.
Bushy-branched, 1-8 dm; lvs spatulate and sinuately toothed, varying to pinnatilobate or subentire; fls pale purple to white, 5 mm wide; pedicels at maturity indurate, 2-8 mm; lower joint of fr turbinate-cylindric, 5-12 mm, or sterile and much-reduced, the upper joint 4- angled or obscurely 8-angled, always evidently larger than the lower, with a somewhat flattened beak, and conspicuously narrowed below to the articulation; 2n=18. Coastal sands; Atlantic coast from s. Lab. to N.C., and along the shores of the Great Lakes; intr. on the Pacific coast and in Australia. Maritime plants and some of these from the Great Lakes (especially about the s. end of Lake Michigan) have the upper segment of the fr plump, 5-9 mm wide, and short-beaked, the beak shorter than the seed-bearing part; these are var. edentula. Most of the plants from the Great Lakes have the upper segment of the fr slender, 3-5 mm wide, and long-beaked, the beak as long as or longer than the seed-bearing part; these are var. lacustris Fernald.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.