Lupinus arboreus
Lupinus perennis
coastal bush lupine, tree lupine, yellow bush lupine
sundial lupine
ascending or erect, branched, woody.
erect, unbranched or sparsely branched distally, usually hollow.
cauline;
stipules 8–12 mm;
petiole 2–3(–6) cm;
leaflets 5–12, blades 20–60 × 3–10 mm, adaxial surface glabrous.
cauline;
stipules 4–12 mm, longer proximally becoming smaller distally;
petiole (2–)5–10(–15) cm;
leaflets 7–11, blades (15–)20–45(–50) × 4–15 mm, abaxial surface appressed to spreading hairy, strigose, adaxial surface green, glabrous.
10–30 cm;
flowers whorled or not.
8–20(–30) cm;
flowers spirally arranged or whorled.
4–10 cm;
bracts deciduous, 8–10 mm.
(2.5–)4–9 cm;
bracts tardily deciduous, 3–6 mm.
4–10 mm.
(3–)5–7(–10) mm.
14–18 mm;
calyx bulge or spur 0–1 mm, abaxial lobe entire, 5–7 mm, adaxial lobe 2-toothed, 5–9 mm;
corolla usually yellow, rarely lilac to purple, banner patch darker or not or white, banner glabrous abaxially, lower keel margins glabrous, adaxial margin ciliate from claw to tip.
(8–)12–16 mm;
calyx abaxial lobe slightly 3-dentate, 5–6 mm, adaxial lobe notched, 4–5 mm;
corolla usually blue, sometimes pink or white, banner glabrous abaxially, upper keel margins ciliate.
4–7 cm, hairy.
3–5 cm, villous.
deciduous, petiolate.
deciduous, petiolate.
8–12, black to tan, often striped lighter, 4–5 mm.
5 or 6.
= 48.
= 48, 96.
Lupinus arboreus
Lupinus perennis
Lupinus arboreus is known from the central California coast southward to northern Baja California; it was introduced as a sand binder and has become naturalized in northern California, Oregon, Washington, and southern British Columbia.
Lupinus arboreus grades into L. rivularis in the North Coast of California. Plants with yellow petals and sweet-smelling flowers are widely cultivated as a sand binder. Hairier plants from the western San Francisco Bay area with yellow banners and blue wings have been called var. eximius; plants with glabrous leaflets and purple petals have been called L. propinquus. Lupinus arboreus hybridizes with L. littoralis and probably other species. Seeds of L. arboreus species are toxic.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Shorter plants with more basal leaves have been recognized as subsp. gracilis; intermediates between the named varieties are abundant. Variety occidentalis was described from Michigan and Wisconsin as differing by its dense pubescence, which is a variable trait.
In the northern part of its range, Lupinus perennis is sympatric with L. polyphyllus and can be differentiated because the latter has more leaflets and a glabrous keel. Lupinus perennis is of conservation concern in some states and is an important host plant for lepidopterans; the federally endangered Karner Blue butterfly relies on L. perennis as a larval host plant and sundial lupine also is a larval host plant for Frosted Elfin (Callophrys irus) and Wild Indigo Duskywing (Erynnis baptisiae) butterflies and several species of moths.
Lupinus perennis is toxic and potentially fatal to livestock, due to the alkaloid D-lupaine (M. Wink et al. 1995).
Lupinus gracilis Nuttall (1834, not Kunth 1824) is an illegitimate name that pertains here.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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