Okla. Stat. tit. 14A, § 14A-3-510: Restrictions on interest in land as security

(1) With respect to a supervised loan in which the principal is

One Thousand Dollars ($1,000.00) or less, and the loan finance

charge calculated according to the actuarial method exceeds twenty-

one percent (21%) per year on the unpaid balances of principal, a

lender may not contract for an interest in land as security. A

security interest taken in violation of this section is void.

(2) This section shall not apply with respect to an open-end

credit plan under which a lender makes advances and takes or retains

a security interest in the principal dwelling of the debtor where

the advances are made in accordance with an established credit limit

of at least One Thousand Dollars ($1,000.00) for the plan.