One of my favorite groundcovers is a plant commonly called barrenwort, bishop’s hat, or fairy wings and is in the genus Epimedium. There are over 20 cultivated species of Epimediums, most of which are herbaceous perennials, in the barberry family. Most species are native to China or parts of Asia with a few species native to the Mediterranean. Plants have been grown for centuries in Asia. Some hybrids have been cultivated for over 100 years. Many of these hybrids are available at independent garden centers in the US.
Plants have heart or arrowhead shaped leaflets (2-7 leaflets per leaf) with fine bristly hairs along the serrated edge. Some selections have bronze or reddish new growth and/or bronze to red/burgundy fall color. The leaves emerge on wiry stems and often last well into winter, making them semi-evergreen in protected landscapes. Four-petaled flowers (often with spurs) occur in arching clusters in May and are available in yellow, pink, peach, lavender, purple, red, or white.
Ideal locations for barrenworts are partial-shade with fertile, moist, well-drained soils. However, Epimedium species and hybrids are noted for their ability to tolerate shady sites with drier soils. Some trees compete with other nearby plants for soil moisture – making it difficult to grow other smaller plants beneath them. Once established, barrenworts can co-exist with trees nicely. During establishment plants will need occasional irrigation, but most establish quickly (within a year or two).
There are several species and hybrids of Epimediums that grow well in Iowa. There are often many cultivars available of each species or hybrid. Most are slow spreading groundcovers that rarely reach more than a foot tall or two feet wide. Most of the species and hybrids listed below are hardy to zone 5 unless noted. All are well-loved, delicate looking, but durable landscape plants.
| Species | Flower color | Comment |
| Epimedium x cantabrigiense | Spurless yellow flowers | Hardy to zone 4; often 1 foot tall; bronze new growth and fall color; Hybrid between E. alpinum and E. pubigerum |
| Epimedium grandiflorum | Long spurred rose, lavender, or white flowers | Bronze new growth that quickly turns green in spring |
| Epimedium x rubrum | Spurless red flowers (red sepals and cream petals) | Noted for reddish new growth and fall color Hybrid between E. alpinum and E. grandiflorum |
| Epimedium x perralchicum | Yellow flowers (often spurless) | Hybrid between E. perralderianum and E. pinnatum colchicum |
| Epimedium x versicolor | Short spurred (often yellow) flowers | Noted for reddish new growth and fall color Hybrid between E. grandiflorum and E. pinnatum colchicum |
| Epimedium x warleyense | Spurred orange/red to yellow flowers | Hardy to zone 4; Hybrid between E. alpinum and E. pinnatum colchicum |
| Epimedium x youngianum | Spurless white to pink flowers | Hardy to zone 4; blooms later than others; Noted for reddish new growth and fall color Hybrid between E. diphyllum and E. grandiflorum |
Other E terms in horticulture:
Easter Lily – Lilium longiflorum cultivars sold before Easter as a symbol of resurrection. Several lilies (including some L. longiflorum cultivars) perform well in Iowa landscapes. Selection and Care of the Easter Lily
Edema – also spelled Oedema – physiological problem that causes unsightly blisters or legions to form on the undersides of plant leaves https://hortnews.extension.iastate.edu/2006/4-12/edema.html
Epiphytes – organisms (moss, airplants, and some orchids) that grow on other plants or have roots that grow in air; epiphytes derive moisture and nutrients from the environment and debris surrounding it; airplants are popular epiphytes. See All About Air Plats
Espalier – a type of training system commonly used on fruit trees in limited spaces; espaliered trees are trained to grow along a flat surface or wall of a building in a protected location
Etiolation – plants growing without light; etiolated plants are often yellow or white with long, weak stems.
Evergreen – a plant that retains green leaves throughout the year
Evapotranspiration – the combination of water loss to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants.
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