  Let $f$ be a proper $k$-coloring of a connected graph $G$ and
$\Pi=(V_1,V_2,\ldots,V_k)$ be an ordered partition of $V(G)$ into the resulting
color classes. For a vertex $v$ of $G$, the color code of $v$ with respect to
$\Pi$ is defined to be the ordered $k$-tuple
$c_{{}_\Pi}(v)=(d(v,V_1),d(v,V_2),\ldots,d(v,V_k)),$ where
$d(v,V_i)=\min\{d(v,x): x\in V_i\}, 1\leq i\leq k$. If distinct vertices have
distinct color codes, then $f$ is called a locating coloring. The minimum
number of colors needed in a locating coloring of $G$ is the locating chromatic
number of $G$, denoted by $\Cchi_{{}_L}(G)$. In this paper, we study the
locating chromatic numbers of trees. We provide a counter example to a theorem
of Gary Chartrand et al. [G. Chartrand, D. Erwin, M.A. Henning, P.J. Slater, P.
Zhang, The locating-chromatic number of a graph, Bull. Inst. Combin. Appl. 36
(2002) 89-101] about the locating chromatic numbers of trees. Also, we offer a
new bound for the locating chromatic number of trees. Then, by constructing a
special family of trees, we show that this bound is best possible.
