Xeric or Sun Ferns

Georgia<br>Perimeter<br>College Botanical Garden

The thought of ferns in the Southern garden conjures up images of lush, arching fronds up to 5 feet waving gently in the breeze of a cool, shady, moist back yard. Such are the voluptuous ferns your grandmother grew, cherished and passed on to friends and family.

Well, moveover Grandma! There is a new group of ferns on the block - xeric ferns - and they break every rule your grandmother used to garden by! Xeric ferns thrive in conditions totally opposite of the woodland habitats we are so familiar with; they prefer full sun, rock soil and desert-like conditions. Our research has shown that these ferns are not impossible to grow in the Souther garden if certain soil preparation procedures are followed. Information on xeric fern culture is found on the next page.

Where do xeric ferns come from? Most of these fern species can be found in Texas, Arizona, New Mexico, Utah and Colorado. A few species, such as Cheilanthes lanosa, Cheilanthes tomentosa and Cheilanthes alabamensis occur naturally in North Carolina, Georgia and Alabama. Most xerics grow in sandy soil, their survival dependent upon excellent drainage. They may also occur in rocky shale and limestone, in overhangs that limit the amount of water reaching roots. The xeric ferns native to the western states thrive with annual rainfall levels of only a few inches, most of theis being in the form of sporadic downpours or winter snows. They grow there on the shadier sides of boulders where they are somewhat protected from the hot, scorching summer sun.

Unique adaptations have developed in the xeric ferns over eons of time that give them the ability to survive conditions that would be devasting to ferns not so equipped. The first adaptation is small size, usually 2-10 inches in overall height. Size definitely matters with the xeric ferns – decreased surface area of the fronds provide a means to reduce water loss! A second adaptation is in the form of a frond coating – scales, hairs or a waxy substance known as farina protect the plants. Farina is sometimes powder-like coating, the undersides of the fronds and giving them a white, silver, or yellow hue. Farina reflects sunlight and seals the pores of the plant. A third adaptation is a Celibate lifestyle – no sex! Ferns that live in arid climates have a tendency toward apogamous (without sex) reproduction. While sperm have no problem swimming in the humid forest, there is seldom enough water in the xeric environment for this to occur. Desiccation (drying) of fronds is yet another feature of the xeric ferns. The fronds may completely shrivel during prolonged dry periods, only to completely rejuvenate and turn green within 24 hours of a rain event. This unique feature of the xerics is called poikilohydry. During prolonged periods of drought fronds may die and wither completely, leaving the plant's underground rhizome to rejuvenate the plant when conditions are again favorable. Finally, apogamous recovery is a characteristic of plants that reproduce asexually to bounce back better than plants that reproduce sexually after the fronds have become desiccated.

Who are these rough, tough, tenacious and sassy yet classy ferns? There are four main genera that fall into the xeric category:

Cheilanthes (Lip Ferns)
Pellaea (Cliff Brake Ferns)
Astrolepis (Star-Scaled Cloak Ferns)
Notholaena (Cloaked Ferns)

These four genera are so difficult to distinguish from each other that John Mickel, one of the great fern gurus of the United States, has lumped all of the xeric ferns into the genus Cheilanthes and referred to them as the Cheilanthoid ferns.

Xeric Fern Culture or How to Grow Xeric Ferns in your landscape.