Sunday, April 27, 2008
Sunday, April 06, 2008
Sunday Nature Photos ~ Special Science Edition
The Bluebonnet (Lupinus texensis) is the state flower of Texas. Most persons around these part equate the plant as such. For me, though, the genera is more interesting. There are different species of lupines in most ecosystems in North America, from the Arctic to the tropics. What evolutionary mechanisms have allowed this group to be so abundant? One answer lies in their ability to fix atmospheric nitrogen. Actually, the culprit are bacteria called Rhizobium which form symbionic relationship with root tissue upon plant germination. The plants utilize the N for protein that is fixed by the bacteria and in turn provide carbohydrates to the Rhizobium for energy and making cell 'stuff'. Only bacteria can fix atmospheric N, thus the N in much of the protein needed for life on this rock originated from such a relationship. Indeed, human life span and health greatly increased when legumes were added to our diet. Not all legumes have this symbiotic relationship, but many do, including the Texas bluebonnet.