Ancient and medieval Indian literature can be classified into different language families such as Indo-European (Sanskrit, Hindi, Marathi, etc.), Dravidian (Telgu, Tamil, Kannada, etc.), Austro- Asiatic (Santhal, Khasi, Savara, etc.), Tibeto-Burmese (Manipuri, Garo, , Tripuri, etc.) All these languages are actively involved in shaping the Indian culture incorporating agriculture. According to time of creation same literature can be divided into three groups Vedic (1500 BC – 1000 BC), Later Vedic (1000 BC - 600 BC) and Post Vedic (after 600 BC). Vedic literature is creative and poetical in form while later Vedic literature is philosophical, theological, speculative in matter and prosaic in form and Post Vedic incorporated both with practical use of it in day today life. Ancient Indian literature first evolved in oral form (Shruti and Smriti) which got written later when script was developed after around 400 BC.
This literature can be further classified, on the basis of sections of the society who will use it, as for intellectual for scholars and theological for masses. The information for intellectuals used the existing knowledge to develop specializations. For example, the Utilization and Regeneration Principles hymn from Atharva Veda (12.1.35) reads: "What of thee, O earth (bhumi), I dig out, let that quickly grow over ; let me not hit thy vitals nor thy heart, O cleansing one." Based on such understanding, the Vedas and Upanishadas disclose specializations which were beneficial for society. Classification of plants and animals into manageable categories came naturally to our ancestors. Some 740 plants and over 250 animals seem to be referred to in our ancient literature, which were classified in many different ways. For example, on the basis of their medicinal property, domestic utility or morphological features, etc. For example, Rig Veda based on growth habit classifies plants into a) Major Group : i) Vriksha (trees), ii) Oushadhi (Useful Herbs), iii) Virudh (Creepers) b) Sub Group: i) Vishakha (Shrubs) ii) Sasa (Herbs) iii) Vratarti (Climbers) iv) Patranavati ( Creepers) v) Alasala (Spreading) c) Other Groups: i) Trina (Grass) ii) Pushpavati (Flowering) iii) Phalavati (Fruiting) iv) Karira (Leaf less). While Atharva Veda based on morphological and other properties. a) Prasthanavati (Spreading), b) Sthambini (Bushy), c) Ekasugna (Single whorl of calyx), d) Amsumathi (With many shoots), e) Khandini (Jointed), f) Vishakha (with extended branches), g) Jivhala (Livlely), h) Nagharisha (harmless,) i) Madhumati (Very sweet).
Theological Base of Ancient Indian literature (on plants) Since this intellectual or scientific information had practical use in day to day life, every danger of misuse causing extinction of plant and animal species was envisaged by the scholars who provided theological base for their rational use through the literature. Literature such as Aranyakas stresses ecological knowledge pertaining to use of forests. Epic such as Ramayana and Mahabharata deal with biodiversity associated with forests. The Aranyakaparva of the Mahabharata mentions about 125 plants. The incident of Lakshagriha (house of lac) suggests the use of forest products on large scale. Similarly, to provide protection to animals, they are assigned to different gods. For example, mouse to Ganpati, Nandi (bull) and snake to Lord Shiva. The process continued and in various Puranas reference of gods associated with trees is common a feature. Even today also the use of plant parts in a pooja is common. For example, jaswand to Lord Ganpati, bilva to Lord Shiva, tulsi to Lord Krishna. Moreover, specialized texts, such as Vishnu Samhita contains some direct instructions in connection with conservation of biodiversity. According to Visnu Samhita, anybody causing any harm to a plant or animal is a sin. The sinner/criminal is liable for punishment in this life and also after death. The punishments are of diverse nature –– financial, corporal, expiatory, and donation of specific articles to a Brahmin.
The beauty of this literature is that it passes test of authenticity in this era also.