Evergreen forests are characterised by the profusion of species, particularly trees and woody climbers and the canopy is closed. The secondary species and exotic weeds are absent. The lower shrubby layer is composed mostly of seedlings and saplings of tree species. The evergreen forests are found between 400 - 1,200 m altitude. It has been observed that there is difference in the physiognomy and composition of species with respect to altitude. The evergreen forests below 700 m are occurring in patches and mostly confined to the sides of water courses where the soil is rather deep. Though there is no marked dominance of any group of trees in evergreen forests below 700 m elevation, there is dominance of certain species in the upper stratum above 700 m forming associations. The important associations are: (i) Vateria - Calophyllum - Cullenia, (ii) Mesua - Cullenia - Palaquium and (iii) Mesua - Palaquium. In the forests above 1,100 m there is dominance of Lauraceae and Heritiera papilio. Epiphytes and mosses tend to increase with altitude while woody climbers decrease.

Species composition below 700 m altitude

The upper stratum trees are Antiaris toxicaria, Artocarpus heterophyllus, Bischofia javanica, Canarium strictum, Chrysophyllum roxburghii, Cynometra travancorica, Diospyros buxifolia, Dipterocarpus indicus, Drypetes elata, Dysoxylum beddomei, Elaeocarpus tuberculatus, Hopea parviflora, Kingiodendron pinnatum, Mangifera indica, Mastixia arborea ssp. meziana, Ormosia travancorica, Persea macrantha, Syzygium chavaran, S. gardneri, Terminalia travancorensis, Vateria indica, etc.

The middle stratum trees are Aglaia lawii, A. malabarica, A. perviridis, Alseodaphne semecarpi-folia var. parvifolia, Aphanamixis polystachya, Beilschmiedia bourdillonii, Cinnamomum mala-batrum, Diospyros spp., Elaeocarpus glandulosus, E. serratus, Garcinia gummi-gutta, G. morella, G. spicata, Gymnacranthera farquhariana, Holigarna arnottiana, Hydnocarpus alpina, Knema attenuata, Lepisanthes tetraphylla, Madhuca neriifolia, Myristica beddomei, M. malabarica, Otonephelium stipulaceum, Reinwardtiodendron anamalaiense, Sageraea dalzellii, Strombosia ceylanica, Syzygium laetum, Vepris bilocularis, Walsura trifolia, etc.

The lower stratum trees are Agrostistachys indica, Atalantia racemosa, Baccaurea courtallensis, Casearia ovata, Isonandra lanceolata, Leptonychia caudata, Meiogyne ramarowii, Nothopegia racemosa, Orophea erythrocarpa, O. uniflora, Psydrax dicoccos, P. travancorica, Turraea villosa and pole crops of upper and middle stratum trees.

The woody climbers are Acacia concinna, Aganope thyrsiflora, Artabotrys zeylanicus, Bauhinia phoenicea, Caesalpinia cucullata, Combretum latifolium, Derris brevipes, Desmos lawii, Entada rheedei, Sarcostigma kleinii, Spatholobus purpureus, Strychnos lenticellata, Tetracera akara, Ventilago bombaiensis, etc.

The main undergrowth are Alpinia malaccensis, Barleria courtallica, Blachia denudata, Ixora nigricans, Munronia pinnata, Psychotria spp., Strobilanthes spp., etc.

Species composition above 700 m altitude

The upper stratum trees are Artocarpus heterophyllus, Calophyllum polyanthum, Chryso-phyllum roxburghii, Cullenia exarillata, Dysoxylum malabaricum, Elaeocarpus tuberculatus, Fahrenheitia zeylanica, Holigarna ferruginea, Mesua ferrea, Palaquium ellipticum, Persea macrantha, Poeciloneuron indicum, Prunus ceylanica, Toona ciliata, Vateria indica, etc.

The middle stratum trees include Actinodaphne malabarica, Agrostistachys borneensis, Beilschmiedia wightii, Bhesa indica, Dimorpho-calyx lawianus, Diospyros paniculata, D. sylvatica, Drypetes malabarica, Melicope lunu-ankenda, Glochidion ellipticum, Gordonia obtusa, Hydnocarpus macrocarpus, Litsea bourdillonii, L. floribunda, L. oleoides, Mallotus tetracoccus, Meliosma pinnata, M. simplicifolia, Trichilia connaroides, Turpinia malabarica, etc.

Aglaia tomentosa, Aporusa acuminata, Ardisia pauciflora, Casearia ovata, Dendrocnide sinuata, Gomphandra coriacea, Lepisanthes erectus, Ligustrum robustum ssp. walkeri, Meiogyne pannosa, Oreocnide integrifolia, Orophea uniflora, Psychotria anamallayana, Sarcococca coriacea, Symplocos cochinchinensis ssp. laurina, Symplocos macrophylla spp. rosea, Syzygium munronii, etc. are common in the lower stratum.

The climbers are Aganosma cymosa, Calamus gamblei, C. pseudotenuis, C. vattayila, Carissa spinarum, Embelia ribes, Kunstleria keralense, Millettia rubiginosa, Pseudaidia speciosa, Rourea minor, Sabia malabarica, Strychnos lenticellata, Toddalia asiatica, etc.

The undergrowth is mainly composed of Amomum canniaecarpum, A. muricatum, Aralia malabarica, Elettaria cardamomum, Lasianthus rostratus, Lepianthes umbellata, Munronia pinnata, Mycetia acuminata, Pandanus thwaitesii, Pavetta calophylla, Psychotria flavida, P. nigra, P. nudiflora, Rhynchotechum permolle, Tarenna monosperma, etc.

In the forests above 1,200 m the trees are pre-dominantly of Lauraceae. The other trees are Calophyllum austroindicum, Heritiera papilio, Mesua thwaitesii, etc.