EUCLIDIUM W. T. Aiton, Hort. Kew., ed. 2, 4: 74. 1812, nom. cons.
Ihsan A. Al-Shehbaz
Tribe: Euclidieae de Candolle, Mém. Mus. Hist. Nat. 7(1): 236. 1821.
Name derivation: Greek eu, well, and kleio, shut, in reference to the indehiscent fruits. I
Type species: Euclidium syriacum (Linnaeus) W. T. Aiton (based on Anastatica syriaca Linnaeus).
Ornithorhynchium Roehling, Deutschl. Fl. ed. 2, 2: 356. 1818. Type species: O. syriacum (Linnaeus) Roehling (based on Anastatica syriaca Linnaeus).
Herbs, annual. Trichomes minutely stalked, 2-forked submalpighiaceous, mixed with fewer simple and rarely 3-forked ones, usually in different sizes. Multicellular glands absent. Stems erect or ascending, simple or branched. Basal leaves petiolate, not rosulate, simple, entire, dentate, or rarely pinnatifid, often withered by flowering; cauline leaves similar to basal, entire or dentate, reduced in size upward. Racemes several flowered, ebracteate, corymbose, elongated in fruit; rachis straight; fruiting pedicels stout, thickened, erect, appressed to rachis. Sepals ovate to oblong, free, caducous, erect, equal, base of lateral pair not saccate. Petals white, erect, only slightly longer than sepals; blade narrowly spatulate, apex emarginate; claw slightly differentiated from blade, shorter than sepals, glabrous, unappendaged, entire. Stamens 6, included, erect, slightly tetradynamous; filaments wingless, unappendaged, glabrous, free, not dilated at base; anthers ovate, apiculate at apex. Nectar glands 4, lateral, 1 on each side of lateral stamen; median glands absent. Ovules 2 per ovary, subapical. Fruit indehiscent, nutletlike silicles, ovoid, subterete to slightly 4-angled, not inflated, not segmented; valves thickened, woody, veinless, rough pubescent, not keeled, smooth, wingless; gynophore obsolete; replum strongly expanded laterally; septum complete, thickened, not veined; style to 1.8 mm, stout, subconical, curved, persistent; stigma capitate, 2-lobed, lobes not decurrent, unappendaged. Seeds aseriate, wingless, oblong, plump; seed coat smooth, not mucilaginous when wetted; cotyledons accumbent or obliquely so.