This section is from the book "Harper's Guide To Wild Flowers", by Caroline A. Creevey. Also available from Amazon: Harper's Guide To Wild Flowers.
Medicago luputina - Family, Pulse. This is a yellow-flowered clover, with flowers in short spikes; and kidney-form, 1-seeded pods. Leaves, with petioles, 3-divided, the leaflets nearly round, often tipped with a small thorn. Pods, when ripe, curl and become black. March to December.
In dry fields and waste places, a weed, throughout the country. Brought originally from Europe.
 
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