ABSTRACT

The Angiosperm Phylogeny Group (APG) system is an updated classification that is established by taking information from recent molecular studies. According to the APG classification, the basal angiosperms are represented as the Amborellales, Nymphaeales and Austrobaileyales (ANA) grade that lead to the major radiation of angiosperms and all the remaining angiosperms are together known as the mesangiosperms. Various classifications based on phylogenetic data have been proposed. But a detailed phylogenetic assessment was much needed. Hence, the APG proposed a new classification system. The basal angiosperms represent the first stage of angiosperm evolution and are popularly known as the ANA grade. The ANA grade comprises of three orders viz., Amborellales, Nymphaeales and Austrobaileyales. Mesangiosperms refers to all the angiosperms except the basal angiosperms. This group comprises of well-supported subclades of magnoliids, Chloranthales, monocots, Ceratophyllales and eudicots. Dilleniales is unclear whether this order should be part of superrosids or superasterids and hence is recognized as a distinct group.