The western park forest belongs to the Pannonian floristic region (Pannonicum), more specifically the Zala floristic district (Saladiense) of the Transdanubian floristic zone. The composition of tree species deviates significantly from the natural forest types of the area, shaped by the local climate and soil conditions. Its natural vegetation cover would be an Illyrian type hornbeam-oak forest (Helleboro odoro-Carpinetum) (Á-NÉR code: K4). In the shrub and herb layers of the forest, we find species characteristic of this association: common privet (Ligustrum vulgare), striped spindle (Euonymus europaeus), red-twig dogwood (Cornus sanguinea), wild garlic (Allium ursinum), snowdrop (Galantus nivalis), etc. In reality, the upper canopy is dominated by groups of black pine (Pinus nigra), Norway spruce (Picea abies), and European larch (Larix decidua), which were planted by Festetics for park landscaping purposes. The lower canopy is dominated by black locust (Robinia pseudo-acacia), tree of heaven (Ailanthus altissima), boxelder (Acer negundo), mountain maple (Acer pseudo-platanus), and Norway maple (Acer platanoides). In the forest herb layer, ivy (Hedera helix), wood meadow-grass (Poa nemoralis), fragrant violet (Viola odorata), and lesser periwinkle (Vinca minor) are common. The 100-year-old hornbeam individuals in the stock evoke the past. The trunk forms of hornbeam (Carpinus betulus) are evidence of past pastoral farming.
The Hévíz swamp basin belongs to the Pannonian floristic region (Pannonicum) and the southwestern Transdanubian floristic zone (Praeillyricum), within the Zala floristic district (Saladiense).
Lake Hévíz, along with its surrounding swamp and marshland, forms an organic hydrogeological, ecological, and phytogeographical unit. Human influences are now predominant over the original natural components.
The lake and its drainage still host many original aquatic, marsh, and swamp species (Butomus umbellatus, Carex ellata, C. oederi, C. paniculata, C. pseudocyperus, Cirsium oleraceum, C. palustre, C. rivulare, Eriophorum angustifolium, Filipendula ulmaria, Galium uliginosum, Hydrocotyle vulgaris, Lathyrus palustris, Nymphaea alba, Peucedanum palustre, Potentilla erecta, Salix cinerea, Scyrpus silvaticus, Schoenus nigricans, Taraxacum palustre, Thelipteris palustris, Triglochin palustre, Veronica scardia). The presence of numerous weed species (Carex hirta, Chelidonium maius, Galium aparine, Sambucus ebulus, Urtica dioica) is also striking.
The most notable wild species in the lake is the warm-climate relic, the coastal bulrush (Schoenoplectus litoralis).
The swamp once extended from Dobogó all the way to the villages of Komárváros and Csákány. On the accumulated thick peat layer, varying water levels led to the formation of reeds (Myriophyllo-Potametum, Hydrochari-Stratiotetum), reedbeds (Scirpo-Phragmitetum), marsh meadows (white-tipped Agrostetum albae, brushy Alopecuretum pratensis), sedge meadows, peat meadows (Schoenetum nigricantis, Juncetum subnodulosi), willow carr (Salicetum cinereae), and scrub-willow forest ecosystems. The initial vegetation of the northern and eastern protective forests was a softwood forest (Salici-populetum) (Á-NÉR code: J4). Over time, ash (Fraxinus angustifolia ssp. pannonica) dominated, likely a narrow-leaved form of the Hungarian ash. This area still belongs to the wet or semi-wet softwood forest (Dryopteridy-Alnetum) (Á-NÉR code: J2) type, with the Hungarian ash as its main tree species. Its characteristic indicator plant is marsh sedge (Carex acutiformis).
Since 1910, artificial afforestation has replaced the natural forest communities. The flat well-paved well in the eastern protective forest and the former drinking trough are reminders of past pastoral activities. In the late 1950s, a poplar (Populus alba) stand was planted, followed by a larch (Alnus glutinosa) plantation after the 1992 final cut. The larch was mixed with Hungarian ash (Fraxinus angustifolia ssp. pannonica) and native species of poplar and willow. In the shrub layer, the dominant species are bird cherry (Padus avium) and black elder (Sambucus nigra). In the herb layer, in semi-wet locations, species like giant goldenrod (Solidago gigantea), hemp (Cannabis sativa), black nightshade (Solanum nigrum), Canadian fleabane (Erigeron canadensis), broadleaf plantain (Plantago major), pigweed (Chenopodium hybridum), white goosefoot (Ch. album), water pepper (Polygonum hydropiper), hemp-nettle (Galeobsis speciosa), tansy (Tanacetum vulgare), aquatic mint (Mentha aquatica), and meadow fescue (Deschampsia caespitosa) can be found. Ivy (Hedera helix) is widespread in both areas. Today, except for the renovated areas, the site is mainly dominated by an old, artificially created, non-diverse larch (Alnus glutinosa) monoculture in significant portions of the land.
Climatic factors, combined with the hydrogeological features of the surrounding area, are the most influential factors shaping the character of the park's plant stock. Similar to botanical gardens and arboretums, this enables the maintenance of a distinctive plant population. The park partially exploits this advantage, primarily through water lilies in the lake and the unique plant species found in the park’s mature tree stock (Metasequoia glyptostroboides, Taxodium distichum).
The park does not possess natural vegetation, and its significance comes primarily from its plant collection, the uniqueness of its vegetation, and its historical background.
