Cacti are ornamental, perennial, succulent and slow growing plants, especially known for their drought tolerant characters (xerophyte). The wide range of forms, shapes, and sizes of their stems and flowers and certain specific characters viz., areoles, spines, glochids etc. make this group of plants unique in the indoor as well as in outdoor gardens, parks and landscapes. An experiment on assessing cacti belonging to different genera for their morphological traits was conducted at the Department of Floriculture and Landscaping, Horticultural College and Research Institute, Tamil Nadu Agricultural University, Coimbatore during 2017-2018. In the experiment for the morphological characterization of certain ornamental cacti genera viz., Hylocereus triangularis, Myrtillocactus geometrizans, Mammillaria beneckei, Hamatocactus setispinus, Ferocactus latispinus, Melocactus caesius and Gymnocalycium mihanovichii, various morphological parameters viz., growth form, characteristic features of ribs, areoles and spines, stem colour, plant height, plant girth, number of areoles have been evaluated for their suitability to be used in tropical landscaping. The morphological characterization of the above said cacti has revealed that Hylocereus triangularis and Myrtillocactus geometrizans can be used as potential rootstocks whereas Mammillaria beneckei, Hamatocactus setispinus, Ferocactus latispinus, and Gymnocalycium mihanovichii can be used as suitable scions in grafting programme.