(N/A) No,it is not correct to say that photosynthesis occurs only in the leaves. While leaves are the primary sites,other green parts of the plant can also perform photosynthesis.
$1$. Photosynthesis by roots: When roots possess chloroplasts and perform photosynthesis,they are called assimilatory roots. Example: $Tinospora$.
$2$. Photosynthesis by stems: In plants like $Opuntia$ (cactus),the stem is modified to act like a leaf. It is green-colored,flat,thick,and fleshy,and it performs photosynthesis. This structure is called a phylloclade.
$3$. Photosynthesis by petioles: In some plants like Australian Acacia,the leaflets fall off very quickly,and the petiole becomes green,flat,and leaf-like to perform photosynthesis. This modified petiole is called a phyllode (often referred to as a cladode in specific contexts).
$4$. Other structures: In plants like $Ruscus$,the stem branches are modified into leaf-like structures called cladodes,which perform photosynthesis.