Anthonius Josephus Maria "Toon" Leeuwenberg (11 August 1930 in Amsterdam – 2010) was a Dutch botanist and taxonomist best known for his research into the genus "Buddleja" at the Laboratory of Plant Taxonomy and Plant Geography, Wageningen.
 He was responsible for sinking many Asiatic species as varieties, notably within "Buddleja crispa".
 In 1962, he worked with Jan de Wilde on the flora of the Ivory Coast.
Buddleja delavayi is a Chinese species discovered by Forrest in the Tali Range above Dali (2000 – 2500 m elevation), Yunnan, in 1910; it is also found in Xizang (Tibet).
 The species was named for l'Abbé Delavay, the French missionary and plant collector, by Gagnepain in 1912.
 The shrub is of interest to the botanist because of its unique (within the genus) resting buds and the different types of inflorescence produced through the year.
Koelreuteria is a genus of three species of flowering plants in the family Sapindaceae, native to southern and eastern Asia.
Buddleja, or Buddleia (also historically given as "Buddlea"), commonly known as the butterfly bush, is a genus comprising over 140 species of flowering plants endemic to Asia, Africa, and the Americas.
 The generic name bestowed by Linnaeus posthumously honoured the Reverend Adam Buddle (1662–1715), an English botanist and rector, at the suggestion of Dr. William Houstoun.
 Houstoun sent the first plants to become known to science as buddleja ("B. americana") to England from the Caribbean about 15 years after Buddle's death.

Question: Which genus has more species, Buddleja or Koelreuteria?
Answer: Buddleja