Western sword fern

Idaho fescue is the plant that the small blue mound in every garden centre is imitating. That mound is almost always Festuca glauca, a European ornamental that dies out in the centre and wants replacing every few years; Idaho fescue is the western North American original, a densely clumping, long-lived perennial bunchgrass with the same fine blue to grey-green foliage on a plant roughly three times the size and with a genuine ecological job. It is a cool-season grass, flowering April to July on stiff stalks that stand about twice the height of the leaf tuft, and it is built underground rather than sideways: thick, deeply penetrating roots carrying symbiotic mycorrhizae, and no rhizomes at all. That is the whole difference between this grass and red fescue, the creeping lawn species in this same group. Idaho fescue never knits into turf, never repairs a gap by running, and cannot be mown as a lawn. What it does instead is hold a slope. The Lady Bird Johnson Wildflower Center calls it drought tolerant and excellent for erosion control, and notes the trap in the same breath: seedlings are only weakly competitive, and only mature plants become strongly competitive. Add that its seed is commercially available but not highly germinable, and the honest summary of establishment is that this is a two-to-three-year project on a weedy site, not a one-season fix. Two more caveats belong up front. There is no Missouri Botanical Garden PlantFinder profile for this species and no RHS Find a Plant entry, so this record rests on a native-plant database and an encyclopedia rather than on horticultural trial guidance, and it is thinner on garden performance than the fescue records around it. And its documented ground is western: rocky slopes and dry openings in woods, from British Columbia and Alberta south through the mountains to central California and Colorado. Nothing cited here describes how it behaves in a humid eastern summer, so this record does not guess.

A spectacular tall vase-shaped native fern with broad upright sterile fronds (resembling ostrich plumes - hence the name) and distinctive contrasting fertile fronds that emerge brown + persistent through winter. The traditional edible fiddlehead source - young curled fronds harvested in early spring are sold seasonally as a delicacy. Spreads vigorously via rhizomes in moist soils; provides good groundcover-scale presence.

A native evergreen fern of eastern North America that holds leathery dark green fronds through winter and provides ground-level songbird cover - ideal for shaded woodland slopes and erosion-prone banks.

Common periwinkle is a trailing, mat-forming evergreen subshrub native to central and southern Europe - from Portugal and France east to the Caucasus and Turkey - grown worldwide as a tough groundcover for its violet-blue spring flowers and glossy dark leaves. It thrives in shade and dry conditions where little else will grow, and establishes quickly. The honest catch is its invasive potential outside its native range: in North America it escapes cultivation readily, forms dense clonal mats that exclude native wildflowers, and - once established - is very difficult to eradicate; all parts are also toxic if ingested.

Bergenia cordifolia (often treated by botanists as a synonym within B. crassifolia) is a tough, evergreen perennial native to the Altai Mountains, southern Siberia and Mongolia, grown for its bold, heart-shaped leathery leaves that flush red-bronze through winter and its deep pink flower spikes in early-to-mid spring. It is one of the most tolerant groundcovers in cultivation - enduring deep shade, poor soil, drought, and hard continental cold (commonly rated to USDA Zone 3 in US horticulture; RHS rates it H7, hardy below -4°F). The honest catch is its shallowly creeping rhizomes: in mild, moist climates they can colonise well beyond the intended planting, and the large, persistent leaves trap fallen debris and are notoriously attractive to slugs and vine weevils.

Liriope muscari is an evergreen, grass-like perennial native to the shady forest understories of China, Japan, and Korea, where it grows at elevations of 330 to 4,600 feet. In gardens it forms dense, weed-suppressing clumps of arching dark-green foliage topped by spikes of lilac-purple flowers in late summer, followed by ornamental black berries - earning it the RHS Award of Garden Merit. It is drought-tolerant and remarkably adaptable, but the honest catch is its behaviour outside its native range: in parts of the eastern United States it is a documented invasive species, spreading by rhizomes and self-seeding into natural areas, and it provides minimal wildlife value compared with native groundcover alternatives.