Convolvulus arvensis L.
NOTE: This species is actionable only when found in field or vegetable seed for planting; tolerance applies.
Common names: bindweed, field bindweed
Fruit a capsule with 2–4 seeds. Seeds wedge-shaped, obovate to broadly obovate in outline, (2.5)3.0–4.5 mm long, 2.0–3.0(3.5) mm wide, 2–3 mm thick. Dorsal side strongly arched toward the apex and sloping downward to a bluntly pointed base, two ventral sides flat or slightly concave and forming a blunt ridge (keel) where they join; cross section sector-shaped. Testa dull, light to dark grey- or orange-brown, with numerous whitish, blunt tubercles or wavy ridges. Hilum oval, +/– sunken, terminal, lying perpendicular to long axis of seed, reddish or same color as testa, 0.3 mm x 0.5 mm, lacking surrounding ridge, with small dome-like elevation at base of hilum. Embryo folded; endosperm hard and clear.
Useful characters for seed identification within Convolvulaceae are size, shape, color, texture, and hilum type, size and color.
Calystegia sepium (L.) R. Br.
Widely distributed in temperate and tropical regions throughout the world.
Native to Europe, North Africa, and temperate Asia.
Temperate, Mediterranean and tropical climates; open areas, arable land, orchards, gardens; also roadsides, neglected areas in both urban and rural environments. Thrives in a wide variety of conditions but does not grow on wet soils.
Convolvulus arvensis is a trailing or twining perennial, to 1.5 m long, with an extensive system of deep roots and fleshy rhizomes. It is one of the most serious weeds of agricultural fields in temperate regions of the world. This species is difficult to eradicate because its seeds remain viable in soil for up to 20 years, and because new shoots can arise from its rhizomes or from rhizome fragments. One plant can produce up to 500 seeds. Convolvulus arvensis is one of ten species covered under the Federal Seed Act for which tolerance is applicable to its introduction (7 CFR 361.6(a)(2)).