Complex sentence: His research centered on phytopathology and on introduction of new, improved varieties of food and forage plants while his field work produced numerous herbarium collections; among them, many new species he described, or were named for him.
Split into simpler sentences: His research centered on phytopathology and on introduction of new, improved varieties of food and forage plants. His field work produced numerous herbarium collections, among them many new species he described, or were named for him.