Paengaroa is a special place for plants. Here you'll find many rare species and more divaricating plants (strange botanical ugly ducklings) than in any similarly sized area in New Zealand.

Because of its special flora, the 107 ha Paengaroa Scenic Reserve became a mainland island in 1990, which also incorporates another 13 ha of Railcorp land.

Rare species

Some of the plants in Paengaroa are nationally rare or have disjunct distributions (are only found in isolated pockets). These include:

• Coprosma obconica - known at only one other North island site and a few sites in the South Island;
• Pittosporum obcordatum - heart leaved kohuhu;
• Korthalsella clavata and K lindsayii - two species of dwarf mistletoe;
• Olearia gardnerii - New Zealand's third rarest tree. The country's largest population is found here. 

Possums and weeds threaten Paengaroa mainland island's native plants and animals. Problem weeds at Paengaroa include ivy, elderberry, Chilean flame creeper, willow and cotoneaster.

Divaricating plants

Divaricating plants - sometimes called inside out plants - are tangled twiggy plants with small leaves. Once they get taller (about 3 m high) some change so completely they are hardly recognisable from their earlier form.

One theory for these ugly ducklings is that the young, twiggy stage protected the plants from moa grazing. The more unattractive the younger plants looked the less chance they had of being eaten. Another theory was that the extreme climate – severe frosts, droughts and frequent floods – could have been the cause.