Does anyone know what plant is that. That seems like a lanceolate leaves to me.
I thought I'd send a picture of bamboo leaves. Bamboo is a monocot and monocots, grasses have parallel venation. The veins in the leaves are parallel to the mid vein and to each other. Dicots have venation similar to a bird's feather.
I am sorry, I am unable to see the venation of your leaves, really need to see the entire plant. Is this a shrub, tree or herbaceous perennial?