The vegetation in the Mount Elgon National Park is a mosaic of montane forest, bushland and grassland communities:
(a) Grassland: <10 cm in height; The park is dominated by Adropogan amethystinus, Pennisetum clandestinumand Digitaria scalarum (Graminae); grass species accounting for 15-60% species composition; occasional shrub and herb species over 10 cm occurring with increasing frequency towards forest edge; grazed intensively by cattle and occasionally by donkeys.
(b) Bushland: dominated by woody herbs and shrub species forming a closed layer between 1-2m above the ground, with occasional tree saplings; tree canopy absent or below 5 % cover; Erica trimera ssp. elgonenis (Ericaceae) abundant in shrub layer and canopy layer (where present) with Artemesia afra (Compositae), Dichrocephella integrifolia (Compositae) and Senacio lyratus (Compositae) particularly abundant in shrub layer; sparse understorey of forbs, pteridophytes and grasses beneath shrub layer; sporadic grazing by cattle in grassy patches; previously cleared for grazing and left to regenerate for six or 15-20 years.
(c) Forest: tallest trees reaching 15-25 m; 50% canopy cover with an overstorey dominated by Afrocrania volkensii (Cornaceae), sometimes forming an association with Podocarpus milanjianus (Podocarpaceae), and no tree understorey; Dicliptera laxata (Acanthaceae) and Impatiens meruensis (Balsaminaceae) particularly abundant in the field layer, with Mimulopsis alpina (Acanthaceae) more abundant in less grazed plots (where its growth form became increasingly shrubby forming a closed layer in patches (< 40 % cover)), and with occasional shrubs occurring in this layer; grazed intensively until either 1983 or 1990 when the human populations in the area were evicted and grazed by cattle with varying intensity since that time.
(d) Forest edge: within 100 m of closed canopy forest and either grassland or bushland communities; tallest trees reaching 10-15 m; <50% canopy cover; shrubs, herbs and tree saplings
forming a patchy layer (<40% cover) sharing species from each community.
(e) Formerly cultivated: abandoned for three or six years; dominated by Rumex ruwensoriensis (Polygonaceae), Plectranthus laxiflorus (Labiatae) and Pilea tetraphylla (Urticaceae), with Urtica massaica (Urticaceae) more common in plots where grazing by cattle was most intense; plots near to Piswa Patrol Hut had been protected from grazing by rangers since abandonment.