(aka: Cystopteris fragilis var. tennesseensis) Cystopteris x tennesseensis is a rare native fern from Nebraska east to Maryland that occurs on cliff ledges and in cracks of alkaline rocks from 500-1,500' elevation. Cystopteris x tennesseensis has been somewhat of a mystery until it was recently determined to be an allotetraploid (how's that for a word of the day) that originated due to a secret rendezvous of the diploid (two sets of chromosomes) Cystopteris bulbifera and Cystopteris protrusa. Some clones from this cross resemble one parent and some resemble the other...ours is closer to Cystopteris protrusa. The 1' long deciduous fronds compose a slowly spreading patch to 8" tall x 3' wide in 5 years. Cystopteris x tennesseensis is quite rare in much of its native habit, so we are delighted to offer nursery-propagated divisions.