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.