Coloured plants, just like all plants, get their food through photosynthesis. This is the process where they use sunlight, water, and carbon dioxide to produce their own food in the form of sugar.

Here's how it works:

1. Sunlight: The chlorophyll in the plant's leaves captures light energy from the sun. Chlorophyll is a green pigment, but other pigments can also be present in the plant, giving it different colors. These pigments may absorb different wavelengths of light than chlorophyll, but they all contribute to the overall process.

2. Water: Roots absorb water from the soil, which is transported up through the plant to the leaves.

3. Carbon dioxide: Leaves take in carbon dioxide from the air through tiny pores called stomata.

4. Photosynthesis: In the plant's chloroplasts, chlorophyll uses the light energy to convert water and carbon dioxide into glucose (sugar) and oxygen. The plant uses glucose as food and releases oxygen back into the air.

The color of a plant doesn't change how it gets its food. Whether it's green, red, purple, or any other color, the plant still relies on the same process of photosynthesis to produce its own food.

The color comes from pigments other than chlorophyll, which may absorb different wavelengths of light but still contribute to the overall process. These pigments can serve other purposes, such as protecting the plant from excess sunlight or attracting pollinators.