Halophytum ameghinoi is a species of herbaceous plant endemic to Patagonia. It is a succulent annual plant, with simple, fleshy, alternate leaves. The plants are monoecious, with solitary female flowers and inflorescences of male flowers on the same plant .
Halophytum has sometimes been placed in its own family, Halophytaceae. For instance, the 2003 APG II system does recognise such a family and assigns it to the order Caryophyllales in the clade core eudicots, although the 1998 APG system had not recognised such a family, placing its members in the family Chenopodiaceae instead.