Pterostylis venosa facts for kids

Pterostylis venosa, often called a greenhood, is a special type of orchid. It grows only in New Zealand. These plants usually live together in groups, forming colonies. Both the plants that flower and those that don't have a group of leaves that spread out or stand up straight. When a greenhood flowers, it has a single yellowish-green or dark green flower with white stripes. It looks a bit like another orchid called P. humilis.

What Does the Greenhood Look Like?

The Pterostylis venosa greenhood is a plant that grows on land (not in water). It's a perennial plant, meaning it lives for more than two years. It's also deciduous, which means its leaves fall off at certain times of the year. This plant is a herb, which means it has soft stems, not woody ones like a tree.

Underground, it has a special part called a tuber. This tuber helps the plant store food. Greenhoods usually grow in groups of three or more plants, forming small communities.

Leaves and Stem

Each greenhood plant has a loose group of two to four leaves at its base. This group of leaves is called a rosette. The leaves can stand up straight or spread out. On plants that are flowering, the leaves are about the same height as the flower stem. The leaves are shaped like a wide oval and are about 30 to 60 millimeters (1.2 to 2.4 inches) long and 10 to 25 millimeters (0.4 to 1 inch) wide.

The flowering stem is about 50 to 100 millimeters (2 to 4 inches) tall. It holds a single flower that can be yellowish-green or dark green, with white stripes.

The Flower's Shape

The flower of the greenhood has a unique shape. The top part, called the dorsal sepal, and the petals are joined together. They form a hood-like shape over the central part of the flower, which is called the column. This hood is sometimes called a "galea."

The dorsal sepal stands mostly upright at its base, then curves forward. The petals are about the same length as the dorsal sepal. There's a wide space between the side parts of the flower, called the lateral sepals, and the galea. The lateral sepals stand upright and spread slightly apart. They are not taller than the galea.

There is a wide V-shaped dip, called a sinus, between the lateral sepals. The labellum (which is like the orchid's "lip") has a fuzzy top surface. It curves and sticks out above the sinus. Greenhoods usually flower between October and February in New Zealand.

How the Greenhood Got Its Name

The Pterostylis venosa was first officially described in 1895. This description was made by a person named William Colenso. He found a sample of the plant on the east side of the Ruahine Range.

The description was published in a scientific book called Transactions and Proceedings of the New Zealand Institute. The second part of the plant's scientific name, venosa, is a Latin word. It means "veiny," which probably refers to the appearance of the plant.

Where Does the Greenhood Live?

This greenhood plant mostly grows in mountain areas. It often lives in Nothofagus forests, which are a type of beech forest. You can usually find it growing in thick layers of fallen leaves or in soft moss beds.

The Pterostylis venosa is found on all three main islands of New Zealand: the North Island, the South Island, and Stewart Island.