觀無量壽佛經義疏 2.90

2.90

「『觀寶樹者，一一觀之。』」樹相多種，故云一一。二、示行數。

"‘As for contemplating the jeweled trees, contemplate them one by one.’" The features of the trees are manifold, hence it says "one by one." Second, showing the number of rows.