1. Asparagus officinalis Linnaeus, Sp. Pl. 1: 313. 1753.
Garden asparagus, common asparagus
Herbs, erect, 1–2.5 m; rhizomes fibrous. Stems annual, densely branched distally; branches finely dissected, ascending to perpendicular, unarmed; cladophylls in clusters of (2–)4–15(–25) per node, filiform, straight or curved, 1–3 cm. Leaves scalelike, 3–4 mm; blade lanceolate, base hardened. Inflorescences in axillary racemes, 1–3-flowered. Flowers some unisexual; perianth campanulate, yellow or yellowish green; tepals connate 1–2 mm, greenish white, 3–8 × 1–2 mm; pedicel 8–12 mm, jointed at or above middle. Berries red, 6–10 mm. Seeds 2–4. 2n = 20, 40.
Flowering summer. Fields, fencerows, roadsides, disturbed areas; 0--2500 m; introduced; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que., Sask.; Ala., Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Europe; Asia; n Africa; naturalized in temperate regions worldwide.
Eaten as a vegetable, Asparagus officinalis has been widely cultivated for its young shoots since ancient Greek times. The species is naturalized in many temperate climates. Mature asparagus has caused poisoning in cattle (J. M. Kingsbury 1964). Young plants can cause dermatitis, and the red berries are suspected of poisoning humans (E. M. Schmutz and L. B. Hamilton 1979). The species is dioecious (J. E. Lazarte and B. F. Palser 1979), and homomorphic sex chromosomes have been identified (H. Loptien 1979).