Of critical importance to plants is the ability to secure adequate photosynthetically active radiation (PAR) for functioning, growth and reproduction. The Opuntia genus represents plants that produce new cladodes (=pads, the primary photosynthetic surface) annually and whose orientation is a response to PAR. Because of the great variability in orientation, I assess pad orientation and tilt at highly local scales to quantify plant response to variations in PAR receipt, using three datasets collected over two field seasons. Several species and putative hybrids were sampled in the West Coyote Hills in Southern California. Data for orientation, shade direction, surface temperatures on differently oriented cladode faces, and cladode tilt were collected. Following normalization of variables, a variety of parametric and non-parametric tests show that the pattern of pad orientation is not unique to species, but is unique to the microsite, where even shade from another pad 5 cm away strongly affects PAR receipt and orientation response. Orientation is not constrained by position on plant. Pads tilt to increase S and E exposure (at the expense of N and W) in response to local shade. Pad face temperatures are higher on sun-facing sides, but the temperature differences are generally small in winter. I observe that pad orientation is best predicted by shade but at the scale of the areole, pad or plant. Results confirm that the high variability observed in orientation in many populations is due to the lack of consideration of shade at highly local scales (plant- or pad-scale), and that even in environments with seemingly ample PAR (sunny, open environments), plants benefit from orienting photosynthetic surfaces to maximize PAR receipt.