The park is known for its rich floral diversity.
It contains diverse ecosystems ranging from
tall alluvial floodplain grassland of early
successional stage to climax stage sal forest
established on uplands. A vegetation study conducted
by Dinerstein (1979) classified six major vegetation
types. Jnawali and Wegge (1993) later modified
this into seven major vegetation types. Sharma
(1999) has classified the vegetation of southwestern
section of the park into 15 different microhabitats.
Major vegetation types found in the park are
Sal Shorea robusta forest
makes above 70% of the forest cover
in the park and grows on well-drained uplands.
S. robusta, Terminalia sps., Buchanania latifolia,
Carrya arboria and Dilenia pentagyna are common
species found in this vegetation type.
is established on relatively old floodplain
and consist of Dalbergia sissoo and Acacia catechu
as dominating tree species. Other tree species
found in this association include Ehretia laevis,
Trewia nudiflora and Mallotus philippinensis.
Murraya koinigii, Callicarpa macrophylla and
Colebrookia opposotofolia are important shrub
species that form dense under story cover.
Moist riverine forest
extends along watercourses. Syzigium cumini,
Mallotus philippinensis, Ficus glomerata, Trewia
nudiflora, and Dalbergia sissoo are among commonly
found tree species in this type of vegetation.
The groung is relatively open and contains humain
soil. Climbing plam Calamus tanusi and Karot
(Teliacora sps), both climbers are indicator
species of moist riverine forest.
Mixed hardwood forest
grows in well-drained areas. Adina Cordifolia,
Casearia tomentosa, lagerstroemia parviflora
and Mitragyna parviflora are among tree species
found in this type.
are similar to Savanna type where ground vegetation
is dominated by grass species with sparsely
distributed tree species. Common grass species
found in this vegetationtype are Saccharum spontaneum,
Imperata cylindrica and Saccharum bengalensis,
Desmostachia bipinnata and Vetiveria zizanoides.
Sparsely distributed tree species include Bombax
ceiba, M. phillippensis, A. cordifolia, Largerstroemia
parviflora and Dalbergia sissoo.
Phantas are the open short grassland
area on previously cultivated fields. Imperata
cylindrica, Saccharum spontanum and Narenga
perphrocoma are the dominating grass species
in phantas. Baghaura and Lamkoili Phantas in
the southwestern section, and Guthi, Shivpur,
Sanosiri, Thulosiri and Chepang phantas are
the typical example of this type.
Tall alluvial floodplain grassland
grows on the riverbeds of Geruwa, Orai and Babai
Rivers. The dominating species of these grasslands
include Saccharum spontaneum, Saccharum bengalensis,
Phragmites karka and arundax.