Species
Introduction
The hickories are members of
the walnut family, Juglandaceae. They constitute the genus Carya,
which is a genus in the subtribe Caryinae of the tribe Juglandeae
(Manos and Stone, 2001). Authorities disagree on the number of
species recognized within the genus, with much of the disagreement
centering on inherent ambiguities in the concept of "species".
The taxa presented here fulfill the following criteria of species
status; 1) they are morphologically distinct (although at times
only obscurely); 2) they each have ecological adaptations which
reduce competition with related, neighboring species; and 3) they
have some level of reproductive isolation which limits gene exchange
with other species (see Grant 1957). Grant (1980) has suggested
that the ultimate criterion of species status is reproductive
isolation. The genus Carya is characterized by numerous interspecific
hybrids, some of which (e.g. C. X lecontei Little) are commonly
encountered when the two parent populations overlap. Detailed
evaluation of the level of reproductive isolation has not been
conducted. After more critical evaluation, some of these taxa
may be placed at other taxonomic levels.
LJ Grauke ,
Research Horticulturist & Curator
USDA-ARS Pecan Genetics
10200 FM 50
Somerville, TX 77879
tele: 979-272-1402
fax: 979-272-1401
e-mail:ljg@tamu.edu
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