Q.(a) Write the simplified version of Angiosperm phylogeny group classification (APG IV). OR

APG IV (2016) is a phylogenetic classification of flowering plants built from DNA sequence data, organising angiosperms into monophyletic clades (basal angiosperms, Magnoliids, Monocots, Eudicots) rather than the older artificial Dicot/Monocot division.

The Angiosperm Phylogeny Group (APG) is an informal international collaboration of plant systematists that has produced a series of classifications of flowering plants (APG I in 1998, APG II, APG III, and APG IV in 2016) based primarily on molecular phylogenetic evidence rather than purely on visible morphology.

Basis of APG IV:

• Uses DNA sequence data — mainly from chloroplast genes (such as rbcL, atpB) and nuclear ribosomal genes (such as 18S rDNA) — combined with careful morphological study, analysed using cladistic (phylogenetic) methods.
• Groups organisms strictly by monophyly — only groups that consist of a common ancestor and ALL of its descendants (monophyletic clades) are recognised as formal taxa; this is a major departure from earlier classifications (e.g. Bentham & Hooker, or even Cronquist), which included paraphyletic groupings not fully supported by evolutionary relationships.

Simplified structure of APG IV:

1. Basal angiosperms (the 'ANITA grade') — the earliest-diverging lineages of flowering plants, including orders such as Amborellales, Nymphaeales (water lilies) and Austrobaileyales.
2. Magnoliids — a large clade including families like Magnoliaceae, Lauraceae, Piperaceae, sharing some features with both monocots and eudicots.
3. Monocots (Monocotyledoneae) — plants with a single embryonic cotyledon, parallel venation, fibrous roots (e.g. grasses, palms, orchids, lilies). …