1. Linum L. (flax)

Plants annual or perennial herbs. Stems 1 to several from the base, erect or ascending, usually branched toward the tip. Leaves opposite or alternate, sessile, the stipules absent or present as small sessile glands (in L. sulcatum). Leaf blades linear to elliptic, the margins entire, the uppermost leaves rarely with small glandular teeth, the surfaces glabrous. Inflorescences panicles or loose paniculate clusters. Flowers perfect, actinomorphic, short- to long-stalked. Calyces of 5 free sepals, these in an outer whorl of 3 and an inner whorl of 2, often appearing somewhat overlapping, ascending, sometimes some or all with glandular teeth, usually persistent at fruiting. Corollas of 5 free petals, these often shed relatively quickly after the flower opens, curved outward to spreading, narrowed to a stalklike base, yellow or blue. Stamens 5, alternate with the petals, the filaments flattened, distinct or fused toward the base, often persistent at fruiting, the anthers attached above but near their base. Pistil 1 per flower, of mostly 5 fused carpels. Ovary superior, more or less 10-locular, each carpel with an incomplete “false septum,” the placentation axile or appearing apical. Styles mostly 5, distinct or slightly to nearly entirely fused, slender, the stigmas ovoid-capitate. Ovules 1 per locule (2 per carpel). Fruits capsules, ovoid or globose to depressed-globose, dehiscing along the false septa into 5 mericarps (each 2-seeded) or along all the septa into 10 mericarps (each 1-seeded), the mericarps wedge-shaped, flat or rounded across the dorsal surface. Seeds asymmetrically elliptic or obovate in outline, flattened, the surface smooth, often somewhat shiny. One hundred and fifty to 225 species, widely distributed in temperate and subtropical zones, especially in the northern hemisphere.