Cheilanthes hirta may form clumps of multiple frond tufts through branching of the rhizomes. Vigorous growth in suitable sites facilitates this. While the plant is often found in sheltered spots among rocks where moisture lingers, the Karoo with its drought and temperature extremes is home to spreading stands of this fern as can be seen here. There are surprises then as to what constitutes a suitable site for a plant species!
Totally exposed to the elements in the crevices among flat rocky surfaces, C. hirta ferns capitalise on the brief moisture retention periods afforded by the rocks themselves. When the often protracted dry cycles arrive, they are prepared. The roots have followed the moisture into the crevices and plugged the openings, denying the dry air access. Roots and rhizomes can thus enjoy the precious moisture longer. The rhizome, hidden below ground survives better while all the above ground plant parts may die off in the hard times. And spores from last season’s fronds wait where the wind may have dispersed them to test conditions for growth when the time comes.
This picture was taken in the Karoo National Park near Beaufort West. This was in the days before lions were introduced into the Park and remaining in one’s vehicle had to be enforced (Shearing and Van Heerden, 2008; JSTOR; www.zimbabweflora.co.za).