The Hungarian lilac belongs to the genus
Syringa, which is distributed across Eurasia, with its centre of diversity in East Asia. The Hungarian lilac is one of only two species of the genus in Europe, the other being the
common lilac (
Syringa vulgaris) with a more southerly distribution on the
Balkan Peninsula and the southern part of the Carpathians. Despite this geographical proximity, the Hungarian and the common lilac are only distant relatives within the genus. Instead, the Hungarian lilac's closest relatives are
Syringa villosa and
S. wolfii (under its synonym
Syringa villosa subsp. wolfii) both of which are native to East Asia. These two taxa together form the sister group of the Hungarian lilac, whereby the split is estimated to have taken place during the
Gelasian period in the
early Pleistocene, about 1.88
Mya. This is consistent with a climatic trend of cooling and desiccation during the Eurasian
Pliocene and
Pleistocene, which is thought to have caused the east-west
disjunctions seen in many Eurasian
taxa. Plant fossils highly similar to the Hungarian lilac have been recovered from
Miocene travertine deposits in
Hungary as well as
Pleistocene interglacial deposits in Hungary and
eastern Germany. For example, the species is known from quarries in
Bilzingsleben (400
kya) and
Weimar-Ehringsdorf (approx. 200 kya), both in
Thuringia. This indicates that the species used to be much more widespread in Central Europe during warm
Quaternary interglacial periods, and was only restricted to its current distribution area in the Carpathians during the
last glacial maximum (LGM). This in turn suggests that the Carpathians served as a
glacial refugium for plant species during the LGM. == Distribution and threats ==