You have said you want to modify your query but you haven't shown us what you currently have.
Normally I would do this in VBA but try following along with these steps and you may be able to accomplish this without any programming.

To modify the query based on the option selected in the option button, you can follow these steps:

1. Add an option group to your form, which allows the user to choose whether to list only Louisiana plants, LA plants or all plants.

2. Assign a value to each option in the option group.

3. In the query that serves as the data source for your form, you need to modify the query criteria to filter the plant families based on the option selected.

   - Open the query in design view.
   - Locate the criteria for the [fsus_TaxonID] field.
   - Replace the existing criteria with an expression that incorporates the option selected in the option group.

4. Save the modified query and run your form. The query will now filter the plant families based on the option selected in the option group.

By implementing these steps, you will be able to modify the query based on the option selected in the option group to list either only Louisiana plants, LA plants or all plants in your form.

Thanks Kevin,  I also would like to use VBA to achieve my goal,   but I like the look and feel of the option button, ideally when I click the LA Flora Only radial button that would execute VBA that would sel from the Q where taxonid is gt 0. And my VBA works but when I unclick (remove the dot) it does not revert to all the records.  How do write "unclick" code?
  Private Sub laflora_Click()
    Dim selectionstr As String
    selectionstr = "SELECT * from MstrFamilyExtQ where FSUS_TaxonID > 0  "
    Me.RecordSource = selectionstr
End Sub

the radial option button is called laflora

Kevin, I think that I may have solved my problem, the unlick value of the option button is 0 and the clicked value is -1 of an if then else in the VBA should solve it....Thanks for the directional guidance.

Help Kevin,

I have now created an option group with values 1-6, the option group is called selectorBox and
Private Sub selectorBox_AfterUpdate()
    MsgBox selectorBox
End Sub
returns the correct value for the option clicked.

How do I do efficiently write a if statement or multiple if statements ..with each value the where clause is changed.

You can use an If Then

If selectorBox = 1 then
    Do Something
ElseIf selectorBox = 2 then
    Dosomething else
End If

Or you can use a Select Case (no video as yet Richard )

Select Case selectorBox
    Case 1
        Do Something
    Case 2
        Do something else
End Select

Funny you bring that up... it's on the list already. :)

Kevin,
Thanks, I have now added a search in conjunction  with the group option box [selectorbox].  my vba looks for the search txt and then requires an "and [list] must be like liststr which is set equal to the selectorbox value.  I msgbox the select statement and everything looks ok, but it is returning all records with the search txt.  it is not down selecting the subset that has a list like "2"- the selectorbox value....

dang, now it seems to be working,,,,,,I did not change anything  
Thoughts   ???

This may have little bearing on your particular issue, but I shy away from "null" having meaning. A "null" the precursor to entering a specific (in your case) classifier. So. . ."not entering" becomes entering. It can work, of course. But, I fear, it will eventually taint the dataset. Why not assign a default to the field which, if you DO wish to skip the entry, can be deleted and convey the useful message that this field has not yet been given a value and requires attention. You've worked hard on this useful db, why leave potential weakness in the seams?