Cheilanthes feei (Slender Lip Fern)
Cheilanthes feei
Table of Contents
Introduction & Discovery
Cheilanthes feei, the Slender Lip Fern, is among the most widely distributed xerophytic ferns of temperate North America, a small calcicolous species that animates limestone and dolomite cliffs from the prairies of southern Canada through the central and southern Rockies and into the deserts and sierras of northern Mexico. Sparse outlying populations on bluffs and ledges in the Driftless Area of Wisconsin, the Ozark Plateau, and scattered midwestern sites document a post-glacial retreat pattern that has fascinated biogeographers. Named in honour of the French amateur pteridologist Louis Viriot Fee (1789 to 1874), whose mid-nineteenth century monographic work on ferns and lichens established many of the cheilanthoid genera still recognised today, the species combines extreme hardiness with a relative horticultural tractability that has made it a staple of specialist alpine and rock-garden collections for more than a century. Slender Lip Fern is smaller and more delicate than most of its North American congeners, with fronds typically 6 to 15 centimetres long, and carries a moderately dense covering of whitish multicellular hairs on the lower surface that gives new foliage a silvery cast before it matures to olive green. The plant grows strictly on calcareous rock, wedging its short creeping rhizome into narrow crevices where winter meltwater and summer thunderstorm pulses supply brief moisture separated by long drought intervals. Recent molecular phylogenetic work by Gerald Gastony, Michael Windham, Kathleen Pryer, Amanda Grusz and collaborators has demonstrated that Cheilanthes in its traditional circumscription is polyphyletic, and this species is now often treated in the segregate genus Myriopteris as Myriopteris gracilis; many floras and horticultural sources nonetheless retain the familiar name Cheilanthes feei, which remains in wide and acceptable use. The species is cytologically complex, with sexual and apogamous populations documented across the range, and is the subject of continuing study by fern cytologists. In gardens it is prized as one of the most cold-hardy lip ferns, as a charismatic subject for limestone crevice gardens and troughs, and as an emblematic representative of the thin-soil cliff flora of the continental heart of North America.
Discovery & Naming
Cheilanthes feei was formally described in the mid-nineteenth century and named by the American pteridologist Thomas Conrad Porter (1822 to 1901), though the specific epithet feei was chosen in honour of the French amateur pteridologist and lichenologist Louis Viriot Fee, whose monographic mid-century works on ferns established many of the cheilanthoid genera still in use today. Type material was collected from limestone cliffs in the United States; published accounts of the time placed the species firmly within the genus Cheilanthes as then broadly circumscribed. Throughout the late nineteenth and twentieth centuries the species received attention from pteridologists including Daniel Cady Eaton, William Ralph Maxon at the Smithsonian Institution, and Charles Alfred Weatherby at Harvard, all of whom discussed its taxonomy, distribution, and morphological variability in regional floras. Cytological investigation in the twentieth century by Herb Wagner, David Lellinger, Alan Smith and collaborators revealed the presence of sexual diploid and apogamous triploid cytotypes within what had previously been considered a single taxon, adding significant complexity to the species concept and prompting careful biogeographic analysis. Late twentieth and early twenty-first century molecular systematic work by Gerald Gastony, Michael Windham, Kathleen Pryer, Amanda Grusz and colleagues demonstrated that Cheilanthes in its traditional broad sense was polyphyletic, and the xerophytic North American lip ferns including this species have been transferred to or resurrected within the genus Myriopteris, originally described by the French pteridologist Antoine Laurent Apollinaire Fee in 1852. Modern taxonomic treatments often cite the species as Myriopteris gracilis, the senior epithet available in Myriopteris, while horticultural and regional floristic literature continues to list it as Cheilanthes feei. The nomenclatural situation remains in flux.
Native Range & Distribution Map
Distribution map showing the native range of Cheilanthes feei.
Biology & Frond Morphology
Cheilanthes feei belongs to the genus Cheilanthes in the family Pteridaceae, producing evergreen, monomorphic, bipinnate to tripinnate-pinnatifid fronds of small to moderate size, commonly 6 to 20 centimetres long and 1.5 to 4 centimetres wide, forming modest tufts from a short-creeping rhizome. blades are narrowly oblong-lanceolate to linear-lanceolate in outline with a gradually tapered apex and a scarcely narrowed base, dissected into small oval to oblong ultimate segments approximately 1 to 3 millimetres across. the upper surface is olive-green and nearly glabrous with only sparse hairs, while the lower surface bears a moderate to dense covering of long whitish to pale tan multicellular hairs and occasional narrow scales. stipes are dark reddish-brown to chestnut, wiry, and usually shorter than the blade, clothed at the base with narrow linear-lanceolate scales. revolute segment margins form a narrow continuous false indusium along each pinnule edge at maturity. fronds that unfurl from coiled fiddleheads (croziers). Like all ferns, it reproduces via spores borne on the underside of fertile fronds rather than flowers and seeds, and its life cycle alternates between a dominant sporophyte (the visible plant) and a small, short-lived gametophyte stage.
Reproduction & Propagation
Propagation of Cheilanthes feei can be achieved through several methods:
- Spores: Collect ripe spores from the underside of fertile fronds, sow on sterilised peat or peat/perlite mix. Do not cover. Keep humid and in bright indirect light. Prothalli (gametophytes) typically develop in 4–12 weeks, and young sporophytes appear after a further 2–6 months.
- Division: Mature clumps with multiple crowns or creeping rhizomes can be divided in spring as new fronds emerge.
- Rhizome cuttings / offsets: Epiphytic genera (Davallia, Polypodium, Phlebodium) can be propagated from 5–10 cm rhizome segments with at least one frond and visible roots.
Cultivation & Substrate
Successful cultivation of Cheilanthes feei depends on matching three conditions to its natural habitat: consistent moisture without waterlogging, a humus-rich yet well-drained substrate, and the correct light level for its frond type — whether dappled woodland shade, bright filtered light, or, for a handful of rock ferns, direct sun.
Substrate: A sharply drained, mineral, strongly calcareous mix appropriate for an alpine rock-crevice fern: approximately one-third coarse grit 3 to 6 millimetres in size, one-third crushed limestone or dolomite chippings or tufa fragments, and one-third a sandy loam-based substrate with a small proportion of sieved leaf mould. The finished mix must feel gritty in the hand, drain instantly on watering, and carry only enough fines to sustain a thin film of moisture. Neutral to distinctly alkaline, pH 7.2 to 8.2. The species is one of the strictest calcicoles among North American ferns and requires limestone or dolomite in the root zone. Acidic media below pH 6.5 cause chlorosis, reduced vigour, and progressive decline. Annual addition of ground limestone to the top-dressing maintains the target pH in container culture. Free and very sharp drainage is non-negotiable. Plant on a raised mound, in a rock crevice, or in a trough with abundant drainage holes over a 2 to 4 centimetre layer of coarse gravel. Water must disappear from the surface within seconds of application and the root zone must dry noticeably between waterings. Standing water and prolonged winter saturation are rapidly fatal. Low. In the native habitat the species grows in thin mineral debris of very low nutrient status, and it is physiologically adapted to minimal fertility. A single light annual top-dressing of dilute balanced fertiliser at one-quarter standard strength is sufficient for container plants; open-ground specimens in a mineral crevice rarely need any supplementary feeding at all. Very low, roughly 5 to 10 percent of the final mix. Use well-decomposed leaf mould or screened compost only, strictly avoiding peat, fibrous bark, or coir which retain too much moisture. The organic fraction provides modest cation exchange and trace buffering but must never dominate the mix; excess organic content encourages crown rot and inverts the natural rupestral substrate profile.
Water: Tap or rainwater, dry between
Light: Full sun to bright partial shade, with full exposure producing the densest hair covering and most compact habit. In the wild Cheilanthes feei colonises open limestone cliffs that receive direct sunlight for much of the day, often on south- and west-facing aspects where radiant heat and reflected glare from pale rock create an intensely bright microclimate. In cultivation the species needs at least four hours of direct sun per day and rewards fuller exposure; deep shade produces lax, pale, scantily haired fronds and drastically reduces longevity. In hot inland gardens light shade from mid-afternoon can be beneficial in summer, particularly for trough-grown plants where substrate volume is limited. Reflected light from surrounding stone or pale gravel top-dressing enhances performance and helps reproduce the characteristic cliff-ledge microclimate of the native habitat. Artificial light under glass requires careful positioning to avoid etiolation.
Humidity: 20-50% (tolerant)
Common Mistakes to Avoid
The most frequent error with Cheilanthes feei is treating it as a conventional woodland fern and planting in moisture-retentive, peat-based, acidic compost in shade; the species responds with rapid chlorosis, crown rot, and death, often within a single season. Planting on an acidic substrate of any kind is similarly fatal: the species is a strict calcicole requiring limestone or dolomite in the root zone. Deep shade reduces hair density, weakens stipes, and predisposes the plant to disease; the species needs bright light to thrive. Overhead watering in cool humid weather encourages fungal leaf spot and disfigures foliage; water at the base of the plant. Burying the crown below the soil surface or under organic mulch invites rot; the rhizome apex should sit slightly proud of the surrounding grade surrounded by fine limestone grit. Using compost heavy with organic matter or peat holds water in the root zone and blocks drainage; use a genuinely mineral mix dominated by grit. Overfeeding produces lax pale foliage prone to pest problems and is unnecessary. Frequent transplanting and disturbance of the rhizome sets back growth by a season or more. Attempting cultivation in humid subtropical zones 9 and warmer without overhead protection against summer rain usually fails.
Seasonal Considerations
Spring brings the principal flush of new croziers, typically from April in southern populations to late May or early June in northern and high-elevation sites. Remove tatty overwintering fronds before new growth expands, apply a single light spring top-dressing of dilute balanced fertiliser at one-quarter standard strength, and begin moderate watering as growth resumes. Summer is the period of active growth and the main cultural challenge: deep infrequent watering at ten to fourteen day intervals is appropriate in hot dry weather, with longer intervals in cooler spells. Monitor fertile fronds for ripening sporangia through mid to late summer and collect spore for propagation. Autumn growth tapers as day length shortens; reduce watering and cease feeding. In humid maritime climates install rain covers before the onset of autumn wet weather. Winter treatment depends on zone: in continental climates leave plants dry under snow cover, while in wet zones protect the crown with a pane of glass or a rock overhang. Avoid winter watering except during prolonged warm dry spells. Inspect troughs in late winter for frost heave and reseat displaced crowns.
Diseases & Pests
Common issues affecting Cheilanthes feei in cultivation:
- Root/rhizome rot: Caused by waterlogged substrate, compacted soil, or overwatering in cool weather. Ensure the growing medium is well-aerated and never let pots sit in standing water for prolonged periods.
- Fungal leaf spot & Botrytis: Brown or grey blotches appear in stagnant, overly humid conditions. Improve air circulation, remove affected fronds, and avoid wetting foliage late in the day.
- Scale insects & mealybugs: The most common fern pests, hiding on stipes and frond undersides. Wipe off with a cotton swab dipped in diluted isopropyl alcohol, or treat with horticultural soap. Many chemical pesticides scorch fern fronds — always test on one frond first.
- Spider mites: Fine webbing and stippled fronds, common in dry indoor air. Raise humidity and rinse fronds regularly with tepid water.
- Frond browning (tip burn): Caused by dry air, direct hot sun, fluoridated or chlorinated tap water (especially in Nephrolepis, Calathea-loving filmy ferns), or soluble-salt build-up from fertiliser. Flush the pot with rainwater and reduce feeding.
Indoor Growing & Terrariums
Cheilanthes feei can be grown indoors as a houseplant or terrarium subject when its humidity and light requirements are met.
Indoor Setup
- Light: Bright indirect light — an east- or north-facing window, or 30–60 cm under an LED grow light (10–12 hours/day). Most ferns scorch in direct midday sun.
- Humidity: 50–80%. Group plants, stand pots on a pebble-and-water tray, or run a humidifier; misting alone rarely raises ambient humidity enough.
- Temperature: 16–24°C (60–75°F) for most indoor species; avoid cold drafts and hot radiators.
- Substrate: Peat-free potting mix with added perlite and orchid bark for drainage; epiphytic genera (Platycerium, Davallia) grow best mounted on bark or in a bark-heavy orchid mix.
- Water: Keep consistently moist but never waterlogged. Let the top 1–2 cm of substrate dry slightly between waterings in winter.
- Air circulation: A gentle fan discourages fungal leaf spot without drying out the fronds.
Landscape & Garden Use
Cheilanthes feei can be used in the garden wherever its hardiness and habitat preferences are matched. Ferns are classic choices for shaded borders, woodland gardens, stumperies, rockeries, stream-side plantings, and ground-cover under trees.
Landscape Tips
- Companions: Hostas, Astilbe, Heuchera, Tiarella, Epimedium, hellebores, snowdrops and other shade-tolerant perennials are classic partners.
- Soil preparation: Incorporate leaf mould or composted bark to improve moisture retention and mimic a forest floor.
- Mulching: A 3–5 cm mulch of chipped bark or leaf litter protects the rhizomes, conserves moisture, and slowly releases nutrients.
- Watering: Establish new plantings with regular deep watering during the first growing season; most hardy ferns need only occasional supplemental irrigation once established.
Conservation & Collector Notes
Cheilanthes feei is globally secure across its enormous range and carries no formal threatened listing. NatureServe ranks the species as globally secure (G5), and it is of least concern across most of its distribution from western Canada through Mexico. Peripheral populations are of greater conservation interest: the species is listed as rare, imperilled, or critically imperilled in several midwestern and eastern states where it persists as disjunct post-glacial relict populations on small limestone cliffs, often in habitats impacted by quarrying, residential development, or recreational climbing. The principal local threats are limestone and dolomite quarrying, construction-related rock removal, invasive species encroachment onto cliff ledges, recreational rock climbing impact on cliff floras, and in some western areas intensified drought associated with climate change. Commercial horticultural demand is modest and is supplied from spore-grown stock, so the species is under no collection pressure. Conservation measures concentrate on habitat protection within national and state parks, nature preserves, and specialist cliff preserves, and on monitoring of small disjunct midwestern populations. Climate projections suggest northward range expansion and upslope shifts, with some loss of low-elevation southern populations likely.
Collector Notes
Cheilanthes feei is a benchmark species for collectors of North American cheilanthoid ferns and a near-essential subject for any serious limestone crevice garden. Provenance matters: collections from the Driftless Area of Wisconsin, the Ozarks, the Colorado Plateau, the prairies of Saskatchewan, and the Mexican Sierra Madre differ in subtle morphological and possibly cytological features and add diversity to a collection. Wild-provenance spore from known sites with elevation and habitat notes is particularly valuable. The American Fern Society Spore Exchange and European specialist suppliers such as the Fern Nursery, the Edinburgh Botanic Garden spore exchange, and various central European alpine nurseries periodically offer fresh material. No formally named cultivars are widely recognised, although regional informal selections exist. Wild collection is legally restricted on public land and ethically inappropriate; small spore harvests from abundant populations with appropriate permits are the only defensible way to introduce new wild-provenance material. Notable mature specimens are grown at the Denver Botanic Gardens, the Montreal Botanical Garden, the Royal Botanic Garden Edinburgh alpine house, Kew's alpine collection, and a number of private specialist collections across central Europe where limestone tufa crevice gardens house exemplary long-lived plants.
Ethnobotany & Cultural Significance
Published ethnobotanical documentation of Cheilanthes feei is scarce, a pattern typical of small cliff ferns whose modest biomass and inaccessible cliff-face habitat offer little utilitarian incentive for traditional use. Broader records for the cheilanthoid ferns mention scattered medicinal uses among Indigenous peoples of North America and Mexico: decoctions of fronds of various lip-fern species have been reported for treatment of respiratory complaints, as mild diuretics, or as topical washes for minor skin conditions. Such uses are documented primarily for Cheilanthes bonariensis, C. sinuata, and similar Mexican species and are not clearly attached to C. feei in the published literature. Early American and Canadian naturalists of the nineteenth and twentieth centuries collected the species extensively as an herbarium subject and a curiosity of the cliff flora but did not record specific utilitarian uses. The species' modern cultural value is chiefly aesthetic and scientific: as a model subject in studies of apogamy and cytotypic variation in ferns, as a biogeographic indicator of post-glacial relict habitat, and as a prized horticultural subject in specialist alpine and rock-garden collections. No commercial wild collection industry exists and no widely marketed selections have been named.
Frequently Asked Questions
Is Cheilanthes feei the same as Myriopteris gracilis?
Yes, they refer to the same fern. Molecular phylogenetic work over the past two decades by Gastony, Windham, Pryer, Grusz and collaborators has demonstrated that Cheilanthes in its traditional broad sense is polyphyletic, and the North American xerophytic lip ferns including this species have been transferred to the resurrected genus Myriopteris. The senior epithet available within Myriopteris is gracilis, so the formally correct name under modern taxonomy is Myriopteris gracilis. Horticultural and regional floristic literature continues to use Cheilanthes feei, and either name is acceptable in general conversation. The plant and its biology are identical regardless of which name is used.
Why does my Cheilanthes feei turn yellow in the middle of the fronds?
Yellowing of foliage in Cheilanthes feei almost always indicates chlorosis caused by inadequate calcium or iron availability in the root zone, typically because the plant is growing in an acidic peat-based compost rather than the limestone-rich mineral mix it requires. The species is a strict calcicole and begins to decline almost immediately in acidic media. To correct, repot into a gritty mineral mix dominated by limestone or dolomite chippings with pH 7.2 to 8.0, remove affected fronds, and reduce watering to encourage new root growth. Improvement should be visible in the next flush of foliage four to eight weeks later. Prevention is always preferable to cure.
Can I grow Slender Lip Fern outside in zone 3 or 4?
Yes, Cheilanthes feei is one of the hardiest xerophytic ferns in North America and succeeds in zone 4 reliably and zone 3 in sheltered sites with good snow cover. The keys are sharp drainage, a limestone-rich mineral substrate, full or nearly full sun, and protection of the crown from prolonged winter wet. Site in a raised crevice garden or a well-drained rock wall where winter meltwater drains immediately away, allow snow to accumulate for insulation, and avoid sites where spring thaw pools around the crown. In areas with unreliable snow cover a light mulch of coarse gravel or fir branches provides modest additional protection without trapping moisture.
Do I need both a male and female plant to get spores?
No. Cheilanthes feei is a homosporous fern and the sexual phase of reproduction takes place on the gametophyte, the tiny heart-shaped haploid generation that develops from germinated spores. A single gametophyte can bear both archegonia and antheridia and often self-fertilise. In addition, many populations of this species are apogamous triploids, in which sporophytes arise directly from gametophyte tissue without fertilisation at all; such lines produce spores without meiosis and establish new populations from a single founder spore. Practically you need only a single mature fertile plant to collect viable spore and raise new plants from it.
How do I tell Cheilanthes feei from Pellaea atropurpurea, which grows on the same cliffs?
Both species share limestone and dolomite cliff habitats throughout much of their overlapping range but are readily distinguished at a glance. Pellaea atropurpurea has glabrous blue-green glaucous fronds, broadly ovate to narrowly triangular pinnules on purplish-black stipes, and a bold, coarse texture; it is emphatically hairless. Cheilanthes feei has smaller, more finely divided fronds with small rounded ultimate segments densely clothed beneath with pale tangled hairs that give a silvery or woolly appearance, on chestnut-brown rather than purple-black stipes. Under a hand lens the hair covering of C. feei is diagnostic. In the field the two species often grow within arm's reach and their contrasting textures are an instructive lesson in convergent adaptation to the same harsh microhabitat.
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Quick Reference Summary: Cheilanthes feei
Golden Rule: Match moisture, light and humidity to each fern’s natural habitat — woodland ferns need shade and humus, rock ferns need drainage, filmy ferns need constant humidity.
Cheilanthes feei, the Slender Lip Fern, is a small calcicolous xerophytic fern of 6 to 20 centimetres, with one of the widest North American ranges among the lip ferns, reaching from southern Canada through the Rockies, Colorado Plateau, and into northern Mexico with outliers on midwestern limestone bluffs. Evergreen bipinnate to tripinnate fronds rise on chestnut-brown stipes from a short creeping rhizome wedged in limestone crevices; frond undersides carry a moderate covering of whitish multicellular hairs that gives new foliage a silvery cast. Exceptionally cold-hardy across USDA zones 3 to 9, the species requires full sun, very sharp drainage, and a limestone-rich mineral substrate at pH 7.2 to 8.2. Often now treated as Myriopteris gracilis following molecular revision, it is propagated from spore, with apogamous triploid populations common. A benchmark alpine rock-garden subject and essential plant for limestone crevice gardens.