Question: Which genus has more species in it, Dipteronia or Syringa?

Context paragraphs:
Syringa oblata: Syringa oblata is a species in the genus "Syringa", in the family Oleaceae.  It is also known as early blooming lilac or broadleaf lilac.

Dipteronia sinensis: Dipteronia sinensis is a plant species in the genus "Dipteronia", endemic to mainland China, and regarded in the soapberry family Sapindaceae "sensu lato" after Angiosperm Phylogeny Group (APG I 1998, APG II 2003) and more recently (Harrington "et al." 2005) ), or traditionally by several authors in Aceraceae, related to the maples.

Syringa oblata subsp. dilatata: Syringa oblata subsp.  dilatata, also known as Korean early lilac, is a subspecies of the species "Syringa oblata" in the genus "Syringa", in the family Oleaceae.

Syringa pinetorum: Syringa pinetorum is a species in the genus "Syringa", in the family Oleaceae.

Syringa tomentella: Syringa tomentella is a species in the genus "Syringa", in the family Oleaceae.

Philadelphus lewisii: Philadelphus lewisii (Lewis' mock-orange)—also known as Gordon's mockorange, Indian arrowwood, wild mockorange (though this can apply to any species in the genus) and syringa—a name that usually refers to the unrelated lilacs.—is a deciduous shrub native to western North America, from northwestern California in the Sierra Nevada, north to southern British Columbia, and east to Idaho and Montana.  It is widespread but not very common, usually appearing as an individual plant amongst other species.  It was first collected by scientist and explorer Meriwether Lewis in 1806 during the Lewis and Clark expedition and the "Philadelphus lewisii" is named after him.

Syringa: Syringa (lilac) is a genus of 12 currently recognized species of flowering woody plants in the olive family (Oleaceae), native to woodland and scrub from southeastern Europe to eastern Asia, and widely and commonly cultivated in temperate areas elsewhere.

Syringa pubescens: Syringa pubescens is a species of flowering plant in the lilac genus of the family Oleaceae, native to Korea and China (Gansu, Hebei, Henan, Hubei, Jilin, Liaoning, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan).

Syringa emodi: Syringa emodi is a species in the genus "Syringa", in the family Oleaceae.  It is also known as Himalayan lilac.

Dipteronia: Dipteronia is a genus of two living and one extinct species, regarded in the soapberry family Sapindaceae "sensu lato" after Angiosperm Phylogeny Group (APG I 1998, APG II 2003) and more recently (Harrington "et al." 2005) )or traditionally by several authors in Aceraceae, related to the maples.

Supporting paragraphs: Dipteronia Syringa
Answer: Syringa