My dictionary (Webster's New World) says:
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1. any of a genus (Lupinus) of plants of the legume family, with palmately compound leaves, racemes of white, rose, yellow, or blue flowers, and pods containing beanlike seeds: used for forage, green manure, etc.
2. the seed of the European lupine (Lupinous albus) used in some parts of Europe as food
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Don't worry about the "palmately..." stuff. What matters is that the plant is a legume, and the seeds are what probably get ground for flour.
The Oxford Companion to Food says:
Lupin: an annual or biennial leguminous plant of the genus (Lupinus) in the pea family. Many lupins are grown for their flowers, but the seeds of a certain species, although bitter and toxic when fresh, can be treated to make them edible and then roaster for eating or for use as a coffee substitute.
Anissa Helou (1994) had described the lengthy preparatin needed to make the seeds into a snack food in the Lebanon. She believes that this food has been part of the diet there since several centuries BC.
Since the discovery in the 1920s of low-alkaloid, 'sweet' lupin plants, cultivars have been developed whose seeds can be used without preliminary preparation. The Saccharatus group of (Lupinous albus) are outstanding in this respect. The cultivar Ultra in this group has been used to produce flour for making lupin pasta.
Toasted and salted seeds, especially of L. albus and L. mutabilis (Andean lupin or tarwi) are served as a snack food or appetizer. Tarwi) seeds are remarkable for their high protein content (almost 50%) and are also the source of an oil which has culinary uses.
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There it is! At last!!
But Helen, please, try to put all your questions in one post.  | 
Need more explication about lupine flour! 
