《现代汉语大词典》defines 凉薯 as:
方言。即豆薯。有的地方也叫地瓜。藤本植物, 花色浅蓝或白色, 结荚, 种子有毒, 块根像甘薯, 可食。
It was the 方言 part that threw me off here.
Baidu Baike just calls it a
other resources also just say something like:
I figured 凉薯 was just MSM but apparently it isn't.
What dialect/topolect is 凉薯 a part of? (if not Modern Standard Mandarin.)