菊薯（学名：Smallanthus sonchifolius）又名雪莲薯或雪莲果，在中国四川被称作“万根苕”，是一种菊科多年生草本植物，原产于南美洲的安地斯山脉。安地斯山脉的居民栽种这种植物做为根茎类蔬菜食用，菊薯的块根含有丰富的水份与果寡糖，尝起来即甜又脆，也可以当做水果食用。在**的市场里，商贩以「地下水果」或「天山雪莲」的名称，来贩卖菊薯的块根，实际上，菊薯和雪莲花是两种不同的植物。

虽然有时候会将豆科的豆薯和同是菊科的菊芋（洋姜）误认为是菊薯，不过它们的块根茎的形状完全不同，豆薯的块根为扁球形，形状似洋葱，菊芋的块茎短圆桶形，形状似芋头，而菊薯的块根为长圆柱形，形状比较像萝卜。菊薯生有两种不同类型的根，一为繁殖根，一为储藏根。繁殖根生长在接近地表的位置下，在根的顶端会形成新的生长点，明年的枝叶会由这个生长点长出，繁殖根的形状和菊芋的块茎很像；储藏根可以生长的比较大且长，可以食用，储藏根中含有菊糖，菊糖是一种很难消化的糖类，这意味着菊薯的根吃起来虽然很甜，可是它所含的卡路里却是非常低。

The yacón (Smallanthus sonchifolius, syn.: Polymnia e****s, P. sonchifolia) is a species of perennial daisy traditionally grown in the northern and central Andes from Colombia to northern Argentina for its crisp, sweet-tasting, tuberous roots. Their texture and flavour are very similar to jicama, mainly differing in that yacón has some slightly sweet, resinous, and floral (similar to violet) undertones to its flavour, probably due to the presence of inulin, which produces the sweet taste of the roots of elecampane, as well. Another name for yacón is Peruvian ground apple, possibly from the French name of potato, pomme de terre (ground apple). The tuber is composed mostly of water and fructooligosaccharide.