Most wicker furniture is made from natural materials that are flammable, which is why you need to check if the wicker lamp shade you are purchasing has been treated for fire resistance.
However, wicker refers to the technique for weaving the lampshade rather than the materials used, so some wicker lamp shades may be made from synthetic materials that are fireproof or at least heat resistant to withstand the heat emitted from the light bulb.
If your wicker light brown lamp shades are made from willow, vines, or palm fibers, they pose a greater fire risk than those made from polyester or PVC.
It is not enough to assume there shouldn’t be an issue as long as the bulb isn’t directly touching the wicker. For safety, it’s ideal to seek a wicker lamp shade that is lined with a fire retardant material like plastic styrene or has been treated with a fireproofing spray.
Always ensure your lightbulb wattage is appropriate for the lamp and the circuit in your home to reduce fire hazards.