Chatham Island greenhood facts for kids

The Chatham Island greenhood (or tutukiwi) is a special type of orchid. Its scientific name is Pterostylis silvicultrix. This plant grows only on Chatham Island and some smaller islands nearby.

When the plant is not flowering, its leaves grow in a circle close to the ground, like a rosette. But when it's ready to flower, leaves also grow on the flower stem. The plant produces a single, see-through white flower with dark green stripes. This greenhood looks a lot like another orchid called Pterostylis banksii. That one grows on the main islands of New Zealand. However, the Chatham Island greenhood has unique orange or reddish-brown tips on its flowers, which Pterostylis banksii does not have.

What Does It Look Like?

The Chatham Island greenhood is a plant that grows from the ground. It is a perennial plant, meaning it lives for more than two years. It's also deciduous, so it loses its leaves at certain times. This plant has an underground tuber, which is like a small storage root. It often grows in groups, forming colonies.

Young plants that are not flowering have light green leaves. These leaves are shaped like an oval or a spear. They are about 30 to 80 mm (1.2 to 3.1 in) long and 10 to 20 mm (0.39 to 0.79 in) wide. They grow on a stem that is 20 to 150 mm (0.79 to 5.9 in) tall.

Flowering plants have three to six leaves. These leaves are 40 to 150 mm (1.6 to 5.9 in) long and 1 to 22 mm (0.039 to 0.87 in) wide. Their bases wrap around the flowering stem. Each plant grows one tall, straight flower stem. This stem can be 100 to 680 mm (3.9 to 27 in) tall. On top of it is a single, see-through white flower with dark green stripes. The flower also has a reddish-brown tip and is about 18 to 25 mm (0.71 to 0.98 in) long.

The top part of the flower, called the dorsal sepal, and the petals are joined together. They form a hood, or "galea," over the central part of the flower, which is called the column. The dorsal sepal is 20 to 25 mm (0.79 to 0.98 in) long and 10 to 16 mm (0.39 to 0.63 in) wide. It is a bit longer than the petals and gets narrower towards its end.

The two side sepals, called lateral sepals, stand upright. There is a wide space between them and the hood. They are joined at their base to close off part of the front of the flower. These lateral sepals quickly narrow into thin tips, about 8 to 10 mm (0.31 to 0.39 in) long. There is a wide, V-shaped dip, called a sinus, between them. The labellum is a green, upright part of the flower that sticks out through this dip.

These orchids usually flower in November and December.

How It Was Named

This greenhood was first officially described in 1864. A scientist named Ferdinand von Mueller gave it the name Pterostylis banksii var. silvicultrix. He published this description in a book called The Vegetation of the Chatham-Islands.

Later, in 2002, three botanists named Brian Molloy, David Jones, and Mark Clements decided that this plant was unique enough to be its own species. So, they changed its name to Pterostylis silvicultrix, giving it full "species status."

Where It Grows

Pterostylis silvicultrix is found in many places on the Chatham Islands. It grows in forests, near streams, in wet areas like bogs, and along the edges of wetlands. You can often spot it growing on the trunks of tree ferns. It lives on Chatham Island itself, as well as on Pitt, Mangere, and South East Island.