Tropism is a fully procedural "Tropism simulation" based system built on custom MeshOps in Modo.

The plugin is based on the Space Colonization Algorithm by Adam Runions who has given me his permission to use it for Tropism. See the paper here http://algorithmicbotany.org/papers/colonization.egwnp2007.pdf
Procedurally create branching meshes using vertices in a mesh layer as attractor points.

https://en.wikipedia.org/wiki/Tropism
Vertices in the mesh layer is working as attractor points

How it works
https://giphy.com/gifs/xT0xeyl3x4kneSDTZS

Performance
https://giphy.com/gifs/xUOxeS9EsjRWAqEuI0

Mesh boundary (advanced)
http://gph.is/2jm9UM8

Features:
-Grow entities like trees, shrubs, plants, veins, lightning bolts in real time
-Grow inside mesh boundaries, on mesh surfaces or in point clouds using the built-in point generator
-Paint vertices on mesh surfaces and see vines grow in realtime where you paint
-Define start location of the growth using one or more locators (roots)
-With several roots all entities will compete for space without branch collisions
-Use deformers, effectors to shape, deform and animate the growth
-Mesh UV-mapping automatically generated
-Use curves as guides for growing
-Leaf system (under development)

Controls:
-Grow length
-Detail (branch splitting)
-Branch curviness
-Radius (using gradients)
-Twist
-Gravity
-Mesh types (Quads, Subsurface, Catmull)
-Polygon detail (optimize for games or for eye candy)
-Randomization within a "configured style" using the controls

-Lights in the scene affects growth (under development)

-Wind system (R&D for the future)

Discuss the plugin here:
https://community.foundry.com/discuss/topic/136719/tropism-for-modo