Copy/Paste the following code to your GroIMP project:
//**********************************************************
/* You will learn:
– the use of a “for” loop on the right-hand side of a rule.
– the automatic generation of several lateral branches.
*/

protected void init()
[ Axiom ==> F(10); ]

public void lateralBranch()
[

// for each F, its length x is taken as the turtle’s
// step length ( L(x) )
f:F(x) ==> f L(x)

// Counting loop (for) with 5 runs.
// Each run generates a daughter branch.
// The variable i is an integer which is incremented by 1
// in each run (1, 2, …, 5).

for (int i=1; i<=5; i++)
(

// MRel(0.1*i+0.2) specifies the position at the mother shoot,
// starting at 20%, + 10% per run.
[ MRel(0.1*i+0.2) RU((-1**i)*30) F(x*0.2) ]
// RU((-1**i)*30) lets the branching angle flip between
// -30 and 30 degrees.
);
]

//**********************************************************