Medicago sativa, commonly called alfalfa, is a forage crop legume. It is a member of the Trifolieae tribe, and a close relative of the reference legume Medicago truncatula.

Genetic data available at LegumeInfo for Medicago sativa
Genetic maps
Data available to download at Data Store

More information and data available at:
Alfalfa newsletter, Medicago Genetic Reports (MGR)
Alfalfa Gene Index & Expression Atlas Database: Web-accessbile database with the MSGI 1.2 transcriptome sequences, annotations, expression profiles, and SNPs identified in this study.
Wikipedia

Image Source: http://www.mdidea.com/products/new/alfalfa_photo05.jpg