Plant profile | Kawakawa (Piper excelsum subspecies. excelsum) | New Zealand native

Plant profile | Kawakawa (Piper excelsum subspecies. excelsum) | New Zealand native

What’s special about New Zealand’s native trees and forests?

New Zealand’s native trees and forests are unique. They look, smell and feel like no other forests, which is not surprising, as more than 80% of the c. 2400 native species of conifers, flowering plants and ferns in the flora as a whole occur nowhere else in the world. This remarkably high level of endemism is one of the reasons for New Zealand being recognised by Conservation International as a world biodiversity hotspot.

Piper excelsum subsp. excelsum | KAWAKAWA PIPERACEAE

The leaves of kawakawa are often conspicuously riddled with holes and notches – the result of browsing by the caterpillars of a native moth, Cleora scriptaria. The hot-tasting leaves are poisonous to most insects and so are avoided, but the larva of this moth is immune and obviously thrives on the diet. 

Distribution & Habitat

Found in lowland forest throughout the North Island, except in colder inland localities; in the South Island, in the west south to Okarito and in the east to Banks Peninsula; also on the Chatham Islands. 

Size

A shrub to small (up to 6 m tall) tree, with a trunk up to c. 6 cm or more in diameter.

Bark

Smooth and brownish black.

Foliage & Habit

Leaves are alternate, smooth-margined, shiny, heart-shaped, 5-10 x 6-12 cm, with seven principal veins radiating from near the base; usually riddled with holes. Branchlets, leaf stalks and veins are wine red to purple-black; leaf stalks have strongly sheathing bases. In forest understorey, kawakawa is a small tree with spindly stems, with distinctive swollen joints, arising from near the ground; older canes are brownish black.

Flowers & Fruits

Inflorescences are spikes (like slender erect candles), often paired, with male and female spikes on different plants. Flowers are stalkless, tiny and interspersed with rounded scales; male flowers have just a few stamens, females a single green ovary each. Fruitlets are small, orange to yellow, with some fusing together and some fusing with the now-fleshy axis of the spike. In the North Island, flowering and fruiting occur in all seasons; in the South Island, flowering is in spring and summer, and fruiting in summer and autumn.

Distinguishing Features

  • Branches and stems are cane-like with swollen joints.
  • Leaves are glossy and heart-shaped.
  • Inflorescences and fruiting structures are solid spikes.
Field Guide Native Trees
1. Leaves have a distinctive shape and vein pattern. 2. Single trunk of a mature kawakawa. 3. A small tree with a well-developed crown and multiple trunks. 4. Foliage and male flower spikes. 5. Spikes of male flowers with pollen scattered on the leaf below. 6. Female spikes, the flowers each reduced to the ovary with a few black, immature stigmas at the centre. 7. Four inflorescences at the fruiting stage; the fruitlets are pressed closely together.
Field Guide Native Trees
NZ Native Trees

Extracted from Field Guide to New Zealand Native Trees by John Dawson

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