Fabaceae – Legume Family
Although members can range from vines, to forbs, to shrubs, and trees, all members of the Fabaceae family display an array of physical similarities. Most noticeably, bilaterally symmetric flowers are unique and readily identifiable. Five united sepals and five petals form an upper “banner,” left and right horizontal “wings,” and a curving “keel” below. Ten stamens and a superior ovary comprise the plant’s reproductive parts.[i] Fruits mature into single chambered pods that, when dry, snap open along two seams to expose (and sometimes explosively hurl) multiple round seeds. Leaves are alternate and (usually) compound (either pinnate, palmate, or trifoliate) with stipules.[ii]
After Orchidaceae and Asteraceae, Fabaceae is the third largest family of the world’s flowering plants with 600 genera and 13,000 species and has the largest representation of genera in the coastal Pacific Northwest.[iii] Comprised of herbaceous, vining, and woody plants this diverse family includes peas, lentils, beans, soy, peanuts, alfalfa, clover, mesquite, lupines, wisteria, as well as Acacia, Red Bud, Locust, and Kentucky coffee trees. This group of plants are economically, agriculturally, culturally, and ecologically significant the world over.
As an ecosystem engineer, Fabaceae, and the symbiotic bacteria harbored in root nodes (rhizobia), increase soil fertility by absorbing and converting atmospheric Nitrogen into a chemical structure more accessible to plant life.[iv] Many members of the Fabaceae are short lived perennials, so when plant wither and decompose, Nitrogen stored in roots returns to the soil where it can be used by successional species.[v] This is what a good gardener is doing when employing “green manures” or cover crops from the in the form of beans, vetch, or clover – all members of Fabaceae – taking advantage of these plants fixing atmospheric Nitrogen, cutting back above ground vegetation, and letting the plant matter compost directly on their planting fields.
It is important to note that although many in this family are edible, the large majority are potentially poisonous, with seed coats containing toxic alkaloids.
Lupinus polyphyllus var. polyphyllus – Big Leaf LupineSpecies Code: LUPO
Habit: Fairly large perennial forb growing between 7 to 60 inches tall.[vi]
Leaves: Basal as well as alternately arranged along the upper stem, leaves are made up of whorls of 9 (or more) long, oblanceolate, elliptic leaflets radiating from a central point.[vii] Combined, these leaflets make large, round leaves measuring up to 40 to 150 millimeters across.[viii] Darker green on the smooth topside, leaves are slightly pubescent and lighter in color below.[ix]
Stems: Erect, smooth, branching and can reach 7 to 60 inches in height.[x]
Flowers: Bilabiate, bilateral, pea-like flowers arranged on elegant racemes ranging in height from 2 to 16 inches tall.[xi] Petals vary in color from violet, to lavender, to pink, to white, with a central yellow (or white) patch that sometimes turns reddish purple.[xii] Like all members of the Fabaceae, flowers have five unequal petals formed into a lower “keel” of two fused petals (which is up curved in L. polyphyllus), a lateral pair of “wings” with shiny backs, and an upright “standard.”[xiii] Ovaries inferior.
Fruits: Develops extremely hairy, two sided pods, that are 2.5 to 4 centimeters long, each holding 3 to 9 rounded, gray seeds.[xiv] Furry seed pods begin as green and turn black as they mature. One side of the seed pod faces the sun unevenly, therefore dries at a faster rate than the shaded half. When unevenly dehydrated the pod buckles, explodes open, and releasing seeds far and wide in an act of epichory, or self-dispersal.[xv] Opened seedpods remain stuck to the raceme and curl up like curled ram’s horns.[xvi]
Ecology: Facultative Species (FAC), occurs in both wetland prairies and dry habitats, tolerates soil drying out seasonally.[xvii]
Notes: May be confused with Lupinus rivularis (Riverbank lupine), which has significantly smaller leaves and redder, or more burgundy colored flowers with white tips on towards the raceme’s top.[xviii] There are hundreds of different lupines occurring across Oregon, with several different types growing in Willamette Valley Wetland Prairies. However, Lupinus polyphyllus is noticeably identifiable by being quite a large plant.[xix] Big leaf lupine is an important pollinator species providing nutrients to native bees, bumbles, and hummingbirds with its pollen-rich flowers that bloom from mid-spring into mid-summer.[xx]
Lupinus bicolor – Bicolored (Miniature) Lupine
Lupinus polycarpus – Small flower Lupine
Lupinus rivularis – Riverbank Lupine
Lupinus sulphureus ssp. Kincaidii – Kincaid’s Lupine
Lotus formosissimus – Seaside Bird’s Foot Trefoil
Lotus unifoliatus – American Bird’s Foot Trefoil
[i] Simpson, M. Plant Systematics 2nd ed. Academic Press, Burlington, MA. 2010.
[ii] Simpson, M. Plant Systematics 2nd ed. Academic Press, Burlington, MA. 2010.
[iii] Pojar, J., Mackinnon, A., Editors Plants of the Pacific Northwest Coast. Lone Pine Publishing, Vancouver, Canada. 2004. 189.
[iv] Fujita, H., Seishiro, A., Kawaguchi, M., Evolutionary Dynamics of Nitrogen Fixation in the Legume-Rhizobia Symbiosis PloS one, 2014, Vol.9 (4), pp.e 93670
[v]Zedler, J., Lindig-Cisneros, R., Restoration of Biodiversity, Overview. Encyclopedia of Biodiversity. Elsevier Inc. 2013.
[vi] Gilkey, H. Handbook of Northwestern Plants, Revised Edition. Oregon State University Press; Corvallis, OR. 2001. 234.
[vii] Guard, J. (1995). Wetland Plants of Oregon and Washington. Lone Pine Publishing, Edmonton, Alberta. 116
[viii] Guard, J. (1995). Wetland Plants of Oregon and Washington. Lone Pine Publishing, Edmonton, Alberta. 116
[ix] Gilkey, H. Handbook of Northwestern Plants, Revised Edition. Oregon State University Press; Corvallis, OR. 2001. 234.
[x] Gilkey, H. Handbook of Northwestern Plants, Revised Edition. Oregon State University Press; Corvallis, OR. 2001.
[xi] Pojar, J., Mackinnon, A., Editors Plants of the Pacific Northwest Coast. Lone Pine Publishing, Vancouver, Canada. 2004. 195.
[xii] Pojar, J., Mackinnon, A., Editors Plants of the Pacific Northwest Coast. Lone Pine Publishing, Vancouver, Canada. 2004. 195.
[xiii] Gilkey, H. Handbook of Northwestern Plants, Revised Edition. Oregon State University Press; Corvallis, OR. 2001.
[xiv] City of Eugene, Seed Collection Manual, Lupinus polyphyllus, 2009.
[xv] Simpson, M. Plant Systematics 2nd ed. Academic Press, Burlington, MA. 2010.
[xvii] USDA Plants Database: <https://plants.usda.gov/core/profile?symbol=LUPO>
[xviii] City of Eugene, Seed Collection Manual, Lupinus polyphyllus, 2009.
[xix] Turner, M., and P. Gustafson. 2006. Wildflowers of the Pacific Northwest. Timber Press, Portland.
[xx] Ley, E.L., S. Buchmann, K. McGuire, and R. Holmes. 2007. Selecting plants for pollinators: a regional guide for farmers, land managers, and gardeners in the Pacific Lowland Mixed Forest Province. Pollinator Partnership and the North American Pollinator Protection Campaign, San Francisco. <http://pollinator.org/PDFs/Guides/PacificLowlandrx9 FINAL.pdf>