plant grow algorithm

How to get started creating an algorithm for 3 D plants?

I used an app for iOS 7.1.2 called Tree Sketch 3.0

http://algorithmicbotany.org/TreeSketch/

to create customized trees & import them as obj. to rhino for architectural scenes.

(unispiring ... I admit)

On recent iOS the app doesn´t work any more, so I figured out, if I should think about making a "light" version of that plant growing thing, with a definition on GH,...

I try to imagine any kind of simple setup to start with,

since I am a middle / low skilled GH user celebrating allways the taste of succes ...running an ordinary GH definition.

 Angelos