Silversword alliance facts for kids
The silversword alliance is a special group of plants. They are also called tarweeds. This group includes about 30 different kinds of plants. They all belong to the sunflower family, which is called Asteraceae.
These amazing plants are found only in Hawaii. They all came from one single plant that arrived on the islands a very long time ago. Over millions of years, this one ancestor plant evolved into many different forms. Today, you can find them as tall trees, small shrubs, mat-like plants, and even climbing vines!
The silversword alliance gets its name from its most famous members: the silverswords. These plants have shiny, silver-colored leaves that look like swords.
What Are Silverswords?
The silversword alliance is divided into three main groups, called genera:
There are three types of silverswords and two types of "greenswords" in the Argyroxiphium group. You can find these on the islands of Maui and Hawaiʻi.
The Wilkesia group has two types of plants, often called iliau. These grow on Kauaʻi.
Most of the plants in the silversword alliance belong to the Dubautia group. These plants are found all over the main Hawaiian islands.
Different Forms of Dubautia
The Dubautia group is very diverse. It includes many different plant shapes:
- Cushion plants: These grow low to the ground, like a soft cushion.
- Shrubs: These are medium-sized woody plants.
- Trees: Some Dubautia can grow into tall trees.
- Lianas: These are woody vines that climb up other plants.
Sometimes, different types of silversword alliance plants grow in the same areas. It can be hard to tell them apart! They can even create new plants by mixing their genes. This is called a hybrid. Hybrids often happen between different Dubautia species. They can also happen between Dubautia and Argyroxiphium plants.
Because of these hybrids, scientists sometimes disagree on the exact number of species. Modern studies suggest there are between 28 and 33 different species in the silversword alliance.
Plant Characteristics
All members of the silversword alliance are perennials. This means they live for more than two years. Beyond that, they live in many different kinds of environments. They have adapted to survive in various places, from dry, sunny slopes to wet, misty forests.
How They Evolved
All the Hawaiian tarweeds came from one ancestor plant. This ancestor was a type of tarweed from the Pacific coast. It was probably similar to plants like Carlquistia muirii that we see today.
The very first ancestor of the silversword alliance was likely a small plant. It probably grew close to the ground, forming mats. It was not much taller than 30 centimeters (about 1 foot). Over millions of years, this small plant evolved and changed. It adapted to the different environments of the Hawaiian islands. This led to all the diverse trees, shrubs, and other forms we see today.
