Buddleja nivea is a vigorous shrub endemic to western China, evergreen in the wild, but deciduous in cultivation in the UK.
 The plant was discovered by Wilson in the Yangtze basin at altitudes of 700 – 3,600 m. Introduced to cultivation in 1901, it was named by Duthie in 1905.
 Several plants similar to the species but originally treated as species and varieties in their own right have now been sunk as "B. nivea" (see Synonyms).
Buddleja × wardii is a naturally occurring hybrid of "Buddleja alternifolia" and "Buddleja crispa" discovered and collected by Frank Kingdon-Ward in 1924 from the mountain riverbanks of south-eastern Xizang (formerly Tibet) at altitudes of 3000–3600 m; "B. alternifolia" and "B. crispa" are the only other Buddleja species found in the area.
 The shrub was named for Ward by Cecil Marquand in 1929.
 White-flowering plants under this name were collected in Tibet by Keith Rushforth and introduced to commerce in the UK in 2013.
Cleyera is a plant genus consisting of 18 species of tender, evergreen shrubs to small trees, mostly native to Mexico and Central America, and one from Eastern Asia.
 In the APG III system it is placed in the family Pentaphylacaceae.
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.
Buddleja colvilei is endemic to the eastern Himalaya; discovered by Hooker in 1849, he declared it 'the handsomest of all Himalayan shrubs.'
 In 1896 the species was awarded the RHS First Class Certificate (FCC), given to plants 'of outstanding excellence for exhibition'.
Buddleja (or "Buddleia") species are used as food plants by the larvae (caterpillars) of a number of Lepidoptera species, including the following.
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.
Buddleja curviflora is a deciduous shrub native to southern Japan and Taiwan, where it grows in thickets on stony slopes at elevations of 100–300 m. "B. curviflora" was named and described Hooker & Arnott in 1838.
 Plants in Taiwan have been described as a separate species "Buddleja formosana" and assessed as Critically Endangered by IUCN, but the distinction is not recognized by Li and Leeuwenberg, who sank "formosana" as a synonym.
Lamprocephalus is a genus plants in the groundsel tribe within the sunflower family.

Question: Between the Buddleja and Cleyera genus plants, which is comprised to the most number of species?
Answer: Buddleja