Telling a cushion plant from a mat plant

A cushion plant grows as a dense, rounded dome. A mat plant grows as a spread, open sheet. The difference is one of shape and density, and it can be checked without touching the plant. The checks below take a few minutes and need no equipment beyond a notebook.

Checks from a distance

1. Stand where the whole plant is visible, and look at its outline against the ground.
2. Note whether the top is domed and level, or whether the plant lies lower and spreads outward.
3. Note how far the plant extends across the ground compared with its height.
4. Look for stems or runners reaching beyond the main body.

Checks close up

Move to a point where the leaves and stems can be seen without leaning on the plant. Look at how the stems meet the soil and at how tightly the leaves are packed. A cushion's stems usually rise from a common mass, with leaves crowded along them. A mat's stems run along the ground and root where they touch soil.

• Is the mass tight, with little ground visible inside it?
• Are the leaves crowded along the stems?
• Do stems run along the ground between the roots?
• Does the edge of the plant look rounded or ragged?

A worked example

Suppose a low green plant sits on a stony slope. From a distance it forms a flat-topped dome about the width of a hand, with a clear outline and no runners. Close up, the leaves are packed along short stems that rise from the centre. The plant is a cushion. If the stems reached out in every direction and rooted at points, the same plant would be a mat.

Recording the result

Write the form beside the species name, if it is known, together with the features that led to the choice. A form noted with its reasons is more useful later than a name alone.