Police involved in the search for Brisbane mother Allison Baden-Clay are due to give evidence on the final day of her husband's committal hearing.

Gerard Baden-Clay could learn on Wednesday if he'll stand trial for murdering his wife and the mother of their three children in April last year.

Prosecutors have alleged Baden-Clay was embroiled in a messy affair and had major debt problems, and those circumstances motivated him to kill his wife.

Police involved in the initial search are expected to testify on Wednesday, along with officers involved in the early stages of the murder investigation.

On Tuesday, botanist Dr Gordon Guymer told Brisbane Magistrates Court some plant matter found in Allison Baden-Clay's hair was not native to the area where her body was found.

He said he identified six plant species from material taken from the body, and all six were found at the family home.

But only two were also found at the creek where her body was found, he said.

Baden-Clay is also accused of interfering with his wife's body.