Phylogeny The oldest fossils attributed to
Carya are
Cretaceous pollen grains from
Mexico and
New Mexico. Fossil and molecular data suggest the genus
Carya may have diversified during the
Miocene. Modern
Carya first appeared in
Oligocene strata 34 million years ago. Recent discoveries of
Carya fruit fossils further support the hypothesis that the genus has long been a member of Eastern North American landscapes, however, its range has contracted, and Carya is no longer extant west of the
Rocky Mountains. Fossils of early
hickory nuts show simpler, thinner shells than modern species, with the exception of
pecans, suggesting that the trees gradually developed defenses to
rodent seed predation. During this time, the genus had a distribution across the Northern Hemisphere, but the
Pleistocene Ice Age, beginning 2 million years ago, obliterated it from Europe. In Anatolia, the genus appears to have disappeared only in the early
Holocene, probably related to human disturbance. The distribution of
Carya in North America also contracted, and it completely disappeared from the continent west of the
Rocky Mountains. It is likely that the genus originated in North America, and later spread to Europe and Asia.
C. sinensis has sometimes been split out in a separate genus as
Annamocarya sinensis, but not by
Plants of the World Online, as genetic data support it being embedded within the other Asian
Carya.
North American hickories '''
Carya sect.
Carya''' – typical hickories '' (black hickory) •
Carya floridana Sarg. – scrub hickory •
Carya glabra (Mill.) Sweet – pignut hickory, pignut, sweet pignut, coast pignut hickory, smoothbark hickory, swamp hickory, broom hickory •
Carya laciniosa (Mill.) K.Koch – shellbark hickory, shagbark hickory, bigleaf shagbark hickory, kingnut, big shellbark, bottom shellbark, thick shellbark, western shellbark •
Carya myristiciformis (
F.Michx.) Nutt. – nutmeg hickory, swamp hickory, bitter water hickory •
Carya ovalis (Wangenh.) Sarg. – red hickory, spicebark hickory, sweet pignut hickory (treated as a variety of
C. glabra by
Flora N. Amer. and
Plants of the World Online) •
Carya ovata (Mill.) K.Koch – shagbark hickory •
C. o. var.
ovata – northern shagbark hickory •
C. o. var.
australis – southern shagbark hickory, Carolina hickory (syn.
C. carolinae-septentrionalis) •
Carya pallida (Ashe) Engl. & Graebn. – sand hickory •
Carya texana Buckley – black hickory •
Carya tomentosa (Poir.) Nutt. – mockernut hickory (syn.
C. alba) •
†Carya washingtonensis Manchester – Miocene of
Kittitas County, Washington '''
Carya sect.
Apocarya''' – pecans '' (bitternut hickory) •
Carya aquatica (F.Michx.) Nutt. – bitter pecan or water hickory •
Carya cordiformis (Wangenh.) K.Koch – bitternut hickory •
Carya illinoinensis (Wangenh.) K.Koch – pecan •
Carya palmeri W.E. Manning – Mexican hickory == Distribution and habitat ==