The phenological behaviour of two herb species, Cassia tora and Argemone maxicana, were studied in Shivtarai Achanakmar regions of Chhattisgarh state, India, from January 2020 to December 2022. Both these species showed marked variations in their phenological behavior studied, such as new foliage, Leaf fall, Flowering and Fruiting, by showing significant variation (P value ˂ 0.05). In the present study, it was revealed that, in Cassia tora, the mean ± SD values of new foliage, leaf fall, flowering and fruiting days were 40±5, 27±5, 127±5, and 102±18 respectively, whereas, in Argemone maxicana, these are 42±6, 36±5, 103±17, 87±2 respectively. In the present study, it was observed that in Cassia tora, the leaf bud busting initiation occurred in July-August, and in Argemone maxicana, it was observed at the end of August. In Cassia tora, the appearance of minimum total mature leaves was observed to occur in September, whereas, in Argemone maxicana, it was in December-January. Moreover, in Cassia tora, the appearance of a maximum number of mature leaves was found in the month of November, whereas in Argemone mexicana, it was in March-May. The length of the reproductive stage was observed to occur in Cassia tora for 3 to 4 months, whereas in Argemone maxicana it was 7-8 months. The Appearance of mature flowers was observed to occur in the month of October for Cassia tora and April-May for Argemone maxicana. The fruit formation was found in Dec-Jan in Cassia tora and in Argemone maxicana in May. The last fruit/fruit fall was initiated in February in Cassia tora and in Argemone mexicana in May to June. The phenological behavior plays a significant role in the study of vegetation patterns in the studied regions, in the field of biochemistry and the field of pharmacology. The plant has evolved in varied phenological phages to attain maximum beneficial phytoconstituents for medicinal purposes in different phenophases and must be studied for future prospects.