刺苋（学名：Amaranthus spinosus），又名竻苋菜（岭南采药录）、勒苋菜（广东），是一种野生苋菜，属苋科苋属，可以食用，但在许多地区都是入侵物种。

一年生草本，茎有棱，常带有紫红色。叶卵型，叶基深入叶柄，彷如叶柄有翼，叶柄基部有两根锐刺， 针刺的基部扁平。穗状花序，上为长穗状，下为团块状，很是特殊，喜生长在干燥荒地。

Amaranthus spinosus, commonly known as the spiny amaranth, spiny pigweed, prickly amaranth or thorny amaranth. It is native to the tropical Americas, but it is present on most continents as an introduced species and sometimes a noxious weed. It can be a serious weed of rice cultivation in Asia.