1、Asterids comprise roughly 80, 000 known species, which is roughly equal to the number of species of ferns, gymnosperms, bryophytes, and gentianaceous dicots combined.
紫草植物目约有8万种，大致与蕨类、裸子植物、苔藓植物和龙胆科双子叶植物所合计的物种数相等。

2、Systematic studies remain relatively limited but suggest that the closest relatives of the Gentianaceae are the families Loganiaceae, Rubiaceae, and Apocynaceae (Gentianales), in that order, plus the Menyanthaceae (Asterales), and that the order Rubiales, which contains the Rubiaceae, the Loganiaceae, and the small family Theligonaceae, is derived from within the gentianaceous order.
系统学研究依然相当受限，但表明龙胆科亲缘关系最近的科是马钱科、茜草科以及夹竹桃科（龙胆目），再加上胡脂叶科（菊目），而鸡饭藤科（茜草亚目）是龙胆目之内的演化枝。