Arborescent habit and secondary growth amongst the monocotyledons apart from asymmetric bimodal Yucca-Agave type of karyotype attracted much attention of the botanists worldwide. Moreover, prolific change in employing taxonomic parameter reaction on relative position of ovary and acquisition of typology of inflorescence aroused more interest in this alliance of petaloid monocytolodons. The present monograph:(i) Seeks attention of the researchers towards after-effects of the aforesaid applications in this alliance.(ii) Reveals evolutionary trends amongst this alliance and related taxa, besides basic tenets of plant morphology and systematics.(iii) Focuses sharply the taxonomic limits at various levels of hierarchy.(iv) Explains importance of multidisciplinary approach particular in case of disputed taxa.(v) Proves that exomorphic and endomorphic features still hold good in the arena of modern trends and technologies.(vi) Benefits students, teachers and researchers worldwide in plant systematics.