Greenhood facts for kids

Quick facts for kids Greenhood
Pterostylis coccina
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Order:	Asparagales
Family:	Orchidaceae
Subfamily:	Orchidoideae
Tribe:	Cranichideae
Subtribe:	Pterostylidinae
Genus:	Pterostylis R.Br., 1810
Type species
Pterostylis curta R.Br., 1810
Synonyms
Genus synonymy Diplodium Sw. Oligochaetochilus Szlach. Plumatichilos Szlach. Bunochilus D.L.Jones & M.A.Clem. Crangonorchis D.L.Jones & M.A.Clem. Eremorchis D.L.Jones & M.A.Clem. Hymenochilus D.L.Jones & M.A.Clem. Linguella D.L.Jones & M.A.Clem. Petrorchis D.L.Jones & M.A.Clem. Pharochilum D.L.Jones & M.A.Clem. Ranorchis D.L.Jones & M.A.Clem. Speculantha D.L.Jones & M.A.Clem. Stamnorchis D.L.Jones & M.A.Clem. Taurantha D.L.Jones & M.A.Clem. Urochilus D.L.Jones & M.A.Clem.

A diagram showing the parts of a Pterostylis metcalfei flower.

Pterostylis coccina with some parts removed to show the inside:
(1) - labellum (lip)
(2) - hinge
(3) - stigma (where pollen lands)
(4) - pollinia (pollen packets)

Pterostylis is a group of about 300 different kinds of plants. They belong to the orchid family, Orchidaceae. These plants are often called greenhood orchids because their flowers look like little hoods.

Greenhoods are ground plants that grow from an underground tuber (like a small potato). They are deciduous, meaning they lose their leaves, and perennial, which means they live for more than two years. You can find them in Australia, New Zealand, New Guinea, New Caledonia, and one island in Indonesia. Their flowers are usually green, sometimes with stripes of brown, red, or white. They are special because of their unique flower shapes and how they get pollinated.

What Do Greenhood Orchids Look Like?

Greenhood orchids are ground plants with a round, underground tuber. This tuber usually lives for about a year and then a new one grows. Sometimes, many new tubers grow, creating a whole group or "colony" of orchids.

Flower Parts and Their Special Hood

The most special part of a greenhood orchid is its hood-like structure called a "galea." This galea is made when the top sepal (a leaf-like part that protects the flower) and two side petals join together.

• The galea curves forward and covers the flower's reproductive parts. It's very important for how the flower gets pollinated.
• The top sepal is usually see-through white with green, red, or brown stripes.
• The two side sepals are joined at their base and form the front of the flower. They often stick out like "points" or "ears" above or to the sides of the galea.
• The third petal is a special lip called the "labellum."
• Like other orchids, the reproductive parts form a structure called the "column." In greenhoods, the column has two mostly see-through "wings" that also help with pollination.

Leaves and Seeds

Greenhood leaves can grow in two ways:

• They can form a circle (a rosette) at the bottom of the plant's main stem.
• Or, they can grow directly on the stem higher up.

A single plant can have one or many flowers on its stem. After pollination, the flower turns into a capsule (a type of fruit) that holds up to 500 tiny seeds. The capsule is shaped like an oval with three ridges. The other parts of the flower dry up and stay attached to the end of the capsule.

Where Do Greenhood Orchids Come From?

The first time European scientists likely saw Pterostylis was in 1770 when Joseph Banks visited Botany Bay in Australia. However, the samples they collected were lost.

The first official description of a greenhood was by Jacques Labillardière. He found a plant on Bruny Island and named it Disperis alata. After a few name changes, it's now known as Pterostylis alata.

Many other botanists, like John White and George Caley, also collected and described greenhoods in the early days of the New South Wales colony. Caley even gave them fun names like Druids Cap patersoni, but he didn't publish his work.

Naming the Genus Pterostylis

The name Pterostylis was officially created by Robert Brown in 1810. He described 19 different species. The name Pterostylis comes from Greek words: pteron means 'wing' and stylos means 'pillar'. In orchids, 'stylos' usually refers to the column, which has wing-like parts in greenhoods.

Today, about 300 different species of greenhoods are known, and about 200 of them have been officially named.

Changes in Classification

For a while, some scientists thought the Pterostylis group should be split into many smaller groups based on how they looked. For example, in 2001, two new groups, Plumatichilos and Oligochaetochilus, were created. Then, in 2002, David Jones and Mark Clements suggested splitting Pterostylis into sixteen different groups!

However, most Australian plant experts didn't agree with these changes. More recent studies in 2010 showed that all greenhoods actually belong together in one large group. So, Pterostylis is still considered a single group, but it has two main subgroups based on how their side sepals bend.

The closest plant relative to Pterostylis is Achlydosa, which is only found in New Caledonia.

Where Do Greenhood Orchids Live?

Greenhood orchids are found mostly in Australia. But they also grow in New Zealand (including some small islands like Chatham Island), New Caledonia, New Guinea, New Britain, New Ireland, and on Seram Island in Indonesia. In Australia, you can find them in every state, but not in the Northern Territory.

They can live in many different places, especially in areas with mild climates. You might see them in:

• grasslands
• heaths (open, shrubby areas)
• scrublands
• woodlands
• forests (even rainforests)

Sometimes, they grow in dry areas, but usually near rocks or cracks where water collects when it rains. In tropical places, they tend to grow higher up in the mountains where it's cooler. Most greenhoods have times when they are dormant (resting) to survive extreme weather. During these times, they live as small tubers underground until the conditions are good for them to grow again.

How Do Greenhood Orchids Get Pollinated?

Most greenhoods rely on insects for pollination. These insects are almost always tiny flies from the family Mycetophilidae or mosquitoes (Family Culicidae).

Here's how it works:

• An insect flies towards the flower, probably attracted by a scent.
• It usually lands on the galea (the hood).
• The insect then enters the flower.
• When the insect passes a certain point or touches a sensitive part of the labellum (the lip), the labellum quickly moves forward. This traps the insect between the column wings, the labellum, and other flower parts.
• As the insect struggles to escape, it either leaves pollen from a flower it visited before, or it picks up new pollen packets (called pollinia) that stick to it.
• The insect then carries this pollen to another greenhood flower, helping the plants reproduce.

The way the labellum actively moves and traps insects, along with the galea, is very special and unique to these orchids!

Growing Greenhood Orchids

Using Greenhoods in Gardens

Greenhoods are quite easy to grow in pots and usually produce many flowers. They can fill a pot with plants in just a few years. Some species, like Pterostylis curta and P. nutans, can grow well in regular orchid potting mix with some coarse gravel added. For some other species, you might need a special greenhouse that stays cool.

It's important to water greenhoods regularly when they are growing. But when they are dormant (resting underground), they need to be kept dry.

Greenhood Species

Hybrid Greenhoods

Sometimes, different species of greenhoods can cross-breed and create new hybrid species. Here are a few examples:

• Pterostylis × aenigma D.L.Jones & M.A.Clem.
• Pterostylis × conoglossa Upton
• Pterostylis × furcillata Rupp
• Pterostylis × ingens (Rupp) D.L.Jones
• Pterostylis × toveyana Ewart & Sharman

Greenhood Species Not Yet Named

Scientists are still discovering and describing new types of greenhoods! Here is a list of some species that have been found but don't have official names yet:

Images for kids

• 

  Pterostylis curta

• 

  Pterostylis grandiflora

• 

  Pterostylis melagramma

• 

  Pterostylis stenochila
  setting seeds

• 

  Pterostylis "Bluff" (unnamed species from N.Z.)

• 

  Pterostylis recurva
  Jug orchid

• 

  Pterostylis sanguinea
  Dark banded greenhood

• 

  Pterostylis vittata
  Banded greenhood

See also

In Spanish: Pterostylis para niños