The lush vegetation and the abundance of species in Malla Strict Nature Reserve result from the altitude differences that are huge on the Finnish scale, from the humidity brought by the proximity of the Arctic Ocean, and from the calciferous bedrock originating from the crumbling schists of the mountain folds. Those schists have emerged from the ancient seabed sediments that now offer their nutrients for the present fell plants to use.

Fell plants live in extremely harsh and varying conditions. The temperatures stay low even in the summer, and the growing season is short. The wintry snow cover offers protection against the drying effect of frost and wind but also shortens the growing season, if it stays on for too long. There are 434 vascular plant species found in the Kilpisjärvi area, 28 of which are only found in this area in Finland.
Malla rarities include the Northern Milkvetch *(Oxytropis lapponica)*, the Lapland Rhododendron *(Rhododendron lapponicum)*, the Glacier Crowfoot *(Ranunculus glacialis)*, the Oneflower Fleabane *(Erigeron uniflorus)* and the Narrowleaf Arnica *(Arnica angustifolia)*.
Mountain Birch forests may be found as high as 600 - 650 metres above sea level in Kilpisjärvi. The Mountain Birch (Betula pubescens ssp. czerepanovii) is the dominant species in the area because Pine does not thrive at this latitude. The best Mountain Birch forests are found on the calciferous slopes of Malla and Saana, and resemble herb-rich forests with their tall herbage. Elsewhere, the Mountain Birch forests are more barren, and their field layer is dominated by dwarf shrubs.
The bare alpine zone, where trees no longer survive, and hardly even shrubs. The dominant plants in this zone are thus dwarf shrubs and other low, dense plants whose underground parts are well-developed. These include the Dwarf Willow *(Salix herbacea)* creeping along the ground, the Diapensia *(Diapensia lapponica)* and the Alpine Azalea *(Loiseleuria procumbens)*. The soil being calciferous, the vegetation on the meadows and in places with late-melting snow beds is quite unique including the Net-leaved Willow *(Salix reticulata)*, and plants on the rocky walls include the Rock Speedwell *(Veronica fruticans)*.
The zone from the Mountain Birch forest up to about 950 metres is called the subalpine zone. There you can still find the Alpine Juniper *(Juniperus communis ssp. nana)*, shrub-like willows and Bilberries *(Vaccinium myrtillus)*. On the meadows in the subalpine zone you will find Globe Flowers *(Trollius europaeus)* and Wood Cranesbills *(Geranium sylvaticum)*.
On the fell top areas, at an altitude of more than 900 metres, there are hardly any dwarf shrubs left; it is the realm of the White Arctic Mountain Heather. Some snow-bed vegetation also thrives there, such as the Snow Buttercup *(Ranunculus nivalis)* and the various Saxifrages *(Saxifraga sp.)*. You can find the Stiff Sedge *(Carex bigelowii)*, Sheep's Fescue *(Festuca ovina)* and Highland Rush *(Juncus trifidus)* up here. It is vital for the fell plants to get their flowers out as soon as the snow melts. They prepare for this during the previous summer so that their buds are ready, waiting for the next summer.