Ask Mr. Smarty Plants

I'm not quite sure what you mean by the plant growing like a vine underneath.   Did you mean that it lies across the ground before growing upwards?   I'm a little confused about that description.   Phytolacca americana (American pokeweed) might possibly lie across the ground before growing up into a bush if it were blocked some way where it grew out of the ground.  It does have clusters of green berries that turn purple.  Although young leaves and shoots are edible if properly prepared, older parts of the plant are highly toxic according to North Carolina State University Cooperative Extension.  They do not mention any skin contact causing rashes.  The Botanical Dermatology Database (BoDD) says that although it has been used to treat some skin conditions (e.g., psora), its juice causes a burning sensation on the skin and dust from the dried root and aspects of the fresh plant can cause eye irritation.

Two vines that grow in Oklahoma have clusters of green berries that ripen to purple.   The leaves of neither of these are very large.  They are:  1)  Smilax rotundifolia (Roundleaf greenbrier) and here are photos from Virginia Tech.  2)  Smilax herbacea (Smooth carrionflower).  The BoDD doesn't list any dermatitis occurring from contact with any species of Smilax, but it has been used medicinally.

If none of these are the plant you found and you have (or can take) photos of it, please go to our Plant Identification page to find links for several plant identification forums that will accept photos of plants for identification.