The genus Lupinus, commonly known as lupine, is a diverse group of plants belonging to the pea family, Fabaceae. Lupines are recognized for their distinctive palmately-divided leaves and colorful, spire-like flowers. Lupine species have a complex and widespread native distribution across multiple continents. This broad geographic range has led to a remarkable number of species, each uniquely adapted to its environment, from arid plains to high mountain slopes.
Global Centers of Origin
The native range of lupines is characterized by two primary and geographically distinct centers of diversity. Lupines are indigenous to the Western Hemisphere (North and South America) and the Old World (primarily the Mediterranean region and parts of Africa). These two groups evolved in isolation and are genetically dissimilar. The New World harbors the vast majority of the genus, with estimates of species ranging from 200 to over 400. In contrast, the Old World is home to a much smaller number, approximately 12 to 13 species.
Diversity in the Western Hemisphere
The Americas represent the major center of lupine speciation and diversity, spanning a vast range from Alaska down to Patagonia. In North America, the greatest concentration of species is found in the western United States, particularly in the mountain ranges and coastal regions of California and Oregon. This area is home to numerous ornamental and wild species, including the iconic Texas Bluebonnet (Lupinus texensis) and the Blue-Pod Lupine (Lupinus polyphyllus) from the Pacific Northwest. The varied habitats of the Western Cordillera have fostered rapid diversification.
South America’s Andes Mountains host another significant center of diversity, where species have adapted to challenging high-altitude conditions. One historically important species is the Andean lupin, or tarwi (Lupinus mutabilis), native to the highlands of Ecuador, Peru, and Bolivia. This species has been cultivated for over 1,500 years by ancient civilizations like the pre-Inca and Inca for its highly nutritious, protein-rich seeds. The Andean region’s unique geography has resulted in one of the highest known rates of species diversification for plants.
Distinct European and African Species
The Old World distribution of lupines is concentrated primarily around the Mediterranean Basin, extending into North and East Africa. Although this area contains far fewer species—only about a dozen—they are historically and agriculturally significant. These Old World species are exclusively annuals, distinguishing them from the perennial varieties found in the Americas. They include the traditional pulse crops: White Lupine (Lupinus albus), Yellow Lupine (Lupinus luteus), and Blue Lupine (Lupinus angustifolius).
These species were domesticated in antiquity and have long been cultivated across the Mediterranean for their seeds, which served as a source of food and animal fodder. They were also historically utilized as green manure, a practice that capitalized on their ability to enrich the soil. This agricultural focus contrasts with the American species, many of which are known primarily for their ornamental value or as wild components of the ecosystem. The Old World group represents a distinct evolutionary lineage that specialized in annual life cycles, surviving the dry Mediterranean summers as seeds.
Ecological Significance in Native Habitats
Across their diverse native ranges, lupines share a crucial ecological role as pioneer species capable of colonizing disturbed or nutrient-poor ground. Their success stems from a symbiotic relationship with specific soil bacteria, primarily Bradyrhizobium species. These bacteria reside in specialized root nodules where they perform nitrogen fixation, converting atmospheric nitrogen into a form usable by the plant. This process allows lupines to thrive in soils that are low in nitrogen, such as sandy dunes or volcanic ash. By fixing nitrogen, lupines act as natural soil enrichers, increasing the fertility of their immediate environment for other plants.