The recognition of the Lupinus montanus complex by morphological traits is discussed. Ecological modification of traits is discussed and the island nature of distribution from mountain peak to mountain peak produces semi-isolated gene pools. Long range dispersal and introgression from other lupines has occurred at the northern end of the distribution in San Luis Potosi, Mexico, developing L. cacuminus. A similar situation occurred in Costa Rica, with L. valerioi the product of introgression from, as yet, an unknown taxon. In Guatemala var. austrovolcanicus represents local introgression from L. kellermanianus, into L. montanus. Both of the Peruvian (L. praestabilis and L. proculaustrinus) taxa are, likewise the result of long range dispersal and introgression. The geographic range of each of the taxa of the complex is plotted and the interrelationship is discussed. The alkaloids have been plotted from random samples of each of the taxa and the data supports the taxonomic treatment and interpretation of their interrelationship. The lupines of Mexico have never been studied monographically. Previous studies have been floristic for states or regions or miscellaneous descriptions, as contributions to the flora of Mexico. To avoid further nomenclatural complications, the earliest named taxa should be identified first. In this sense, the first taxon named for Mexico was Lupinus mexicanus Cerv. ex. Lag. (1816), which has been identified (Dunn, 1972). Lupinus montanus H.B.K. (1823) was the second epithet published for Mexico, concurrently with L. elegans H.B.K. (Humboldt et al., 1823: 478). Both of the types of these taxa are available at Paris, France, with microfiche illustrations now widely distributed. The topotype material was studied and dissections of 50 collections, representing the geographic range of L. montanus were made, and the mean measurements were used to prepare the illustrations of L. montanus and allies presented in this paper. The illustration of L. montanus was sent to Paris and the curator of the herbarium kindly varified that the illustration accurately represents the species by matching it with the type specimen. Since L. elegans H.B.K. is the first epithet in a different complex of lupines, it will be treated, as soon as the rest of the complex is understood. With this approach it is believed, after ten years of study of the Mexican lupines and dissection of over 100 types for Mexico, that the taxonomic treatment of the L. montanus complex for Mexico and Central America can be presented. C. P. Smith (1948: 608) reported two South Ameri