Pale Yellow Lupine

Annual, Herbs, Taproot present, Nodules present, Stems erect or ascending, Stems less than 1 m tall, Stems solid, Stems or young twigs glabrous or sparsely glabrate, Stems or young twigs sparsely to densely hairy, Leaves alternate, Leaves petiolate, Stipules conspicuous, Stipules seti form, subulate or acicular, Stipules persistent, Stipules adnate to petiole, Leaves compound, Leaves palmately 5-11 foliate, Leaf or leaflet margins entire, Leaflets 5-9, Leaves hairy on one or both surfaces, Inflorescences racemes, Inflorescence terminal, Bracts conspicuously present, Bracts very small, absent or caducous, Bracteoles present, Flowers zygomorphic, Calyx 5-lobed, Calyx 2-lipped or 2-lobed, Calyx hairy, Petals separate, Corolla papilionaceous, Petals clawed, Petals reddish brown, maroon, Petals blue, lavander to purple, or violet, Banner petal ovoid or obovate, Wing petals narrow, oblanceolate to oblong, Wing tips obtuse or rounded, Keel petals auriculate, spurred, or gibbous, Stamens 9-10, Stamens or anthers dimorphic, alternating large and small, Stamens monadelphous, united below, Filaments glabrous, Style terete, Fruit a legume, Fruit unilocular, Fruit freely dehiscent, Fruit elongate, straight, Fruit oblong or ellipsoidal, Fruit exserted from calyx, Fruit internally septate between the seeds, Fruit hairy, Fruit 1-seeded, Fruit 2-seeded, Seeds ovoid to rounded in outline, Seed surface smooth, Seeds olive, brown, or black, Seed surface mottled or patchy.

Lupinus luteolus is a species of lupine known by the common names pale yellow lupine and butter lupine. It is native to the coastal mountain ranges of Oregon and California as far south as the Transverse Ranges, where it grows in open habitat such as clearings and sometimes disturbed areas. It is an annual herb with a rigid stem growing to maximum heights anywhere between 30 centimeters and 1.5 meters, and known to exceed that at times. Each palmate leaf is made up of 7 to 9 hairy leaflets 1 to 3 centimeters long. The inflorescence is a raceme of crowded whorls of flowers each just over a centimeter long. The flower is often pale to bright yellow, but can be blue or pinkish. The fruit is a hairy, rounded or oval legume pod generally containing 2 seeds.