Some people with chest pain have normal or minimal narrowing of heart arteries; in these patients, vasospasm is a more likely cause for the pain, sometimes in the context of Prinzmetal's angina and syndrome X.
You are here. Pure Live Seed. Pure live seed (PLS) is a measure used by the seed industry to describe the percentage of a quantity of seed that will germinate. PLS is obtained by multiplying the purity percentage by the percentage of total viable seed, then dividing by 100.
385 million Age, in years, of the oldest known seedlike fossils. The most ancient viable seed, from a 2,000-year-old date, was excavated from a fortress near the Dead Sea. Last June, researchers reported in Science that the seed germinated after planting and developed much like its modern counterparts.