potato
薯 centers on the potato as a starchy tuber, especially in compound words for potato varieties.
薯 combines the plant radical 艹 with 署, which likely contributes the sound. The character was created to represent the potato plant.
The grass radical 艹 sits above 署, like a potato plant growing above the ground with its tubers hidden below.
For ショ, imagine a potato being thrown into a show: show -> ショ, and the potato lands on stage.
grated yam
potato (Solanum tuberosum)
Japanese yam (Dioscorea japonica)
water yam (Dioscorea alata); winged yam; purple yam
water yam (Dioscorea alata); winged yam; purple yam
water yam (Dioscorea alata); winged yam; purple yam
fish cake
sweet potato
grated yam soup
potato starch