The 5ha reserve at Springvale, 7km from Alexandra, is home to several unusual and rare plants.
"Most are smaller than a 50c piece, so they're hard to spot unless you get down on your hands and knees," Doc biodiversity assets ranger Craig Wilson said.
Three spring annuals are among the rare plants which thrive in the saline soil on the site.
Two of them - Myosurus minimus, also known as mousetail and Ceratocephala pungens "battle it out" for the title of world's smallest buttercup, he said.
The third is the tiny and rare cress Lepidium kirkii.
"There are only 11 places in the world this plant grows and there's very few of the plants around. The Springvale site houses the third biggest population of the cress."
Saline soil used to be common in Central Otago, but only 100ha of the original 40,000ha of those rare ecosystems were left in the district, Mr Wilson said.
"The rare plants which grow in this site are tiny because they've adapted to growing in really dry, stressful sites and there's not enough moisture for them to grow any bigger. "
"Some of them are only found in Central Otago and provide habitat to unique insects, especially moth species."
Because the plants were so small, they were often overlooked and people were unaware how valuable they were, he said.
A field trip will be held at the new reserve on Thursday, September 22, starting at 1.30pm. The plants would be flowering then, so it was the best time to view them, Mr Wilson said.
He will lead the tour and identify the tiny plants. The new reserve is on State Highway 85, 7km from Alexandra, near the Springvale-Clyde road.
