Irwin's greenhood facts for kids

Pterostylis irwinii is a special kind of orchid known as a greenhood. It grows only in New Zealand, meaning it's endemic there. When this plant is flowering, it has straight, narrow leaves on its stem. But when it's not flowering, its leaves form a flat, circular shape close to the ground, like a rosette. This orchid has a single green flower with cool see-through white stripes and tips that are reddish-brown.

About Irwin's Greenhood

Irwin's greenhood is a plant that grows from the ground, not on trees. It's a perennial, which means it lives for more than two years, and it's deciduous, so it loses its leaves at certain times. This plant is a herb, meaning it has soft stems, and it grows from an underground tuber (like a small potato). Often, you'll find these orchids growing together in small groups.

Plants that aren't flowering have two or three leaves shaped like eggs. These leaves are about 40 to 150 mm (1.6 to 5.9 in) long and 30 to 50 mm (1.2 to 2.0 in) wide.

When the plant is flowering, it has a single flower that is 35 to 45 mm (1.4 to 1.8 in) long and 10 to 12 mm (0.39 to 0.47 in) wide. This flower sits on a reddish stem that is 150 to 200 mm (5.9 to 7.9 in) tall. The stem has three to five leaves wrapped around its base. These stem leaves are long and narrow, like a spear, measuring 60 to 170 mm (2.4 to 6.7 in) long and 4 to 5 mm (0.16 to 0.20 in) wide.

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 called the column. The dorsal sepal is about 43 to 48 mm (1.7 to 1.9 in) long and 14 to 16 mm (0.55 to 0.63 in) wide, and it feels a bit rough. It stands up straight at first, then curves forward.

The side parts of the flower, called the lateral sepals, stand mostly upright. They have narrow tips that are 24 to 27 mm (0.94 to 1.1 in) long. There's a deep dip, or sinus, between them, and a wide space between them and the hood. The labellum, which is a special lip-like petal, is 15 to 18 mm (0.59 to 0.71 in) long and about 3 mm (0.12 in) wide. It's curved, reddish-brown, and sticks out above the dip. These orchids usually bloom between October and January.

How it Got its Name

The Pterostylis irwinii orchid was officially described for the first time in 1997. This was done by three botanists: David Jones, Brian Molloy, and Mark Clements. They published their description in a magazine called The Orchadian.

The second part of the plant's name, irwinii, is a way to honor a person. It was named after James Bruce Irwin, who collected the very first example of this plant, called the type specimen. He found it in 1991 near a place called Erua, close to the Tongariro National Park.

Where Does it Live?

Irwin's greenhood seems to like wet places in tall forests or on steep hills. It especially likes areas with rocks that are basic, like limestone.

On the North Island of New Zealand, you can find it in the Waimarino River floodplain (a flat area next to a river that sometimes floods) and near Cape Palliser. On the South Island, it grows in the northwest region, going as far south as the Buller River. There have also been a few sightings even further south.

Is it in Danger?

Yes, Irwin's greenhood is considered a plant that needs protection. Under the New Zealand Threat Classification System, it is listed as "threatened and nationally endangered." This means there aren't many of these orchids left, and they are at risk of disappearing if we don't protect them.