The ancient Hinduism scriptures , namely in Vedas our Rishies identified and classified plants according to various charastics , form , size etc. In Rig-Veda 7.4.5 plants are divided into two categories - Ausadhi (herbs) and Vanaspati (trees).
आ यो योनिं देवकृतं ससाद क्रत्वा हय 1 ग्निमृतां अतारीत |
तमोषधीश्च वनिनश्च गर्भं भूमिश्च विश्वधायसं बिभर्ति ||RV 7.4.5 ||
The herbs and the trees , and the earth , contain as a germ that all
supporting Agni , who occupies a place provided by the gods , that by
his function he may convey (the offerings) to immortals.
In Atharvaveda according to scholars , we find again plants are divided into sub-categories and we find more classification of plants. In Atharvaveda they have been classified according to color , character, habitats and use.
As mentioned in the book - Plant Biology and Biotechnology: Volume I: Plant Diversity, Organization, Function and Improvement Bir Bahadur, Manchikatla Venkat Rajam, Leela Sahijram, K.V. Krishnamurthy. In Atharvaveda planta are classified in 8 classes. (Page 4-5)
The Atharvaveda in particular classified plants into eight classes :
Sasa(herbs) , Visakha (plant with spreading branches) , Manjari
(Plants with long clusters), Sthambini (bushy plants ) ,Prastanavati
(those which extend on the ground , i.e. creepers , Anshumati ( with
many branches ) , Ekashringa ( with monpodial growth) and Kandani
(plants with knotty joints) .
प्रस्त्रुणती स्तम्बिनीरेकशृङ्गा प्रतन्वतीरोषधीरा वदामि |
काण्डीनीर्या विशाखा र्ह्यमि ते वीरुधो वैश्वदेवीरुग्रा: पुरुषजीवनी: ||
AV 8.7.4 ||
The spreading , the bushy , the one-spathed , the extending herbs do i
address ; those rich in shoots , jointed (kandin) , that have
spreading branches (Vishakha) ; i call for thee plants that belongs to
all the gods formidable , giving life to men.
Similarly we find the classification based on leaves and fruits bearing plants in mantra no. 27 of same sukta.
पुष्पवती: प्रसुमती : फ़लिनिरफ़ला उत |
संमातर इव दुर्हामस्मा
अरिष्टतातये ||AV 8.7.27 ||
Rich in flowers , rich in shoots (prasu) , rich in fruits , also those
lacking fruits - like joint mothers , let them milk unto this man in
order to his freedom from harm.
Here in below mantras plants are classified according to sweetness in their parts.
मधुमन्मूलं मधुमदग्रमासां मधुमन्मध्यं वीरुधां बभूव |
मधुमत् पर्णं मधुमत
पुष्पमासां मधो: संभक्ता
अमृतस्य भक्षो घृतमन्नं दुर्हतां गोपुरोगवम्
||AV 8.7.12 ||
Rich in sweets the root , rich in sweets the tip of them , rich in the
sweets the middle of the plants ; rich in sweets the leaf , rich in
the sweet the flower of them ; partaking of sweet a drink of nectar
(amrita) , let them milk out ghee , food , with milk (go) as chief