Those nice folks over at Xfrog Inc. have released 130 free items of foliage for you to use in your next 3ds Max visualisation. These free models are fully 3d and created to a high standard from real life examples.
These collections provide an easy way to add life and realism to your projects. Many of the items have 3 to 9 age variations allowing you extra flexibility for randomising the scene.
Why not use the mental ray 'Multi/Sub-Map' map type to add subtle variations into the planting diffuse colour, with the added benefit of letting 3ds Max and mental ray do all the hard work for you. The easiest way is to load a seperate 'Color Correction' map onto each new additional diffuse texture slot and slightly change its properties, but reusing the original diffuse texture bitmap.
Ensure you take note of the first 3 options in the 'Multi/Sub-Map.' My preferred selection method is to use 'Random' as the placement selection method ('Swith Color/Map based on' option). By doing this you are also optimising your scene's memory footprint for rendering. (Click on below screen shots to enlarge)