头花草科（又名萼角花科或萼角科），共有6属约40种，分布在南美洲南部。

本科植物为一年或多年生草本；单叶互生，叶有裂；花小，排成头状花序，花瓣5，肉质，萼管具棱；果实为瘦果。

1981年的克朗奎斯特分类法单独列出一个头花草目，放在菊亚纲下面，1998年根据基因亲缘关系分类的APG 分类法认为可以直接放到菊目下。

Calyceraceae is a plant family in the order Asterales. The natural distribution of the about sixty species belonging to this family is restricted to the southern half of South-America. The species of the family share a unique character combination of florets which are set in a flowerhead on a common flowerbase with strawlike bracts at the foot of each floret, while the flowerhead is surrounded one or two rows of leaf-like bracts which are not merged with each other though. The mostly five (but sometimes four or six) fused petals form a funnel or tube and remain on top of the fruit when the seed is ripe, while the stamens alternate with the petals and are fused with the tube of petals near the base, and finally the fruit contain one seed and two carpels.