Vogel's great legacy: The oil flower and oil-collecting bee syndrome

- The oil flower/oil bee pollination syndrome was described by Vogel in 1969.
- Over 34 years, Vogel's work documented many aspects of this syndrome.
- This pollination system has arisen many times in flowering plants and bees.
- How oil collecting and oil secretion arose remains unexplored.
- Oil chemistry, its uses, and secretory mechanism are still poorly known.

Ranking with the great 18th and 19th century botanists, Kölreuter, Sprengel, and Müller, Stefan Vogel was the 20th century plant biologist who discovered and explored an entirely new pollination syndrome - oil flowers and oil-collecting bees. His work inspired us to work on oil flowers and their associated bees in regions he did not visit. Throughout our work we were continually impressed with the creativity and thoroughness with which he explored this novel plant-pollinator system. Yet, time and subsequent explorations have elaborated and expanded on his work. Here we summarize his contributions and bring up to date the story of the oil flower pollination system focusing primarily on oil bees. Specifically we point out: our increased knowledge about the numbers of plants and bees partnering in this syndrome, the unrealized flexibility in the system; new findings of the chemistry of the floral oils, the use of the oils among various oil-collecting bees and the chemical signals used by at least some oil bees for floral host recognition. We also discuss what is known of the pollen and nectar hosts of oil-collecting bees.