Mount Aspiring National Park has a unique feature. Its mountain range splits the park into two halves that experience contrasting weather conditions and therefore differ in vegetation. The west is the wetter side since the mountain tops break the clouds at high altitude leaving less rain for the drier east.
In eastern valleys, visitors observe several mountainous forests that are made of rimu (Dacrydium cupressinum), miro (Prumnopitys ferruginea) and kahikatea (Dacrycarpus dacrydioides). Mountain beech trees (Fuscospora cliffortiodes) are common in high altitudes preferably drier environments whereas silver beech (Lophozonia menziesii) prefers wetter areas. Red beech (Fuscospora fusca) dominates the lowlands but shares some warmer sites with ribbonwood trees (Plagianthus regius), a deciduous species.
Areas above the treeline are home to herbs and tussocks as well as several alpine flower species such as the mountain buttercup (Ranunculus populago) or the alpine sundew (Drosera arctui).