Indeterminate nodules are the only type found in Caesalpiniodeae and Mimosoideae and the most common type in Papilionoideae (Sprent, 2001; p. 32). As a result of the variety of ways the plant is infected by rhizobia, there are different types of nodules.
Vitamins are organic compounds that are needed in even smaller quantities than minerals by the horse, although no less critical. Vitamins can be divided into two groups, the fat soluble vitamins A, D, E and K and the water soluble C and B-complex vitamins.
Selenium, in conjunction with vitamin E, is necessary for proper immune system function and to protect the integrity of cell membranes. However, a delicate balance exists between too little selenium and too much. In many areas of the country, horses ingest sufficient selenium while foraging, but in other areas, selenium needs to be part of the horse's diet.