Rich, dark, almost black foliage is enhanced by bright golden yellow flowers, opening in the morning. 3 to 4 ft. Sun. Can be grown as an annual.

Oenothera lamarkiana 'Black Magic'

Dark Evening Primrose

Rose pink flowers on 6 inch plants in summer. Drought tolerant. Best in sun. Zones 6-10.

Oenothera kunthiana 'Glowing Magenta'

Glowing Evening Primerose

Brilliant yellow 1 1/2 inch flowers open during the day. 1-3 ft. Edible. Sun to light shade.

Oenothera tetragogona 'Sundrops'

Evening Primrose

Sky-blue flowers edged in pink, fading to white. Moist soil. Shade.

Omphalodes cappadocica 'Starry Eyes'

Venus' Navelwort

Chalk white flowers in nodding clusters on striped foliage, which is 6 inches to 1 ft tall. Metallic violet blue fruit follows. Partial to shade.

Ophiopogon jaburan 'Variegata'

Variegated Mondo Grass

Evergreen, to 15" grass-like leaves, lilac flowers that become bright blue berries. Sun to partial shade. Zone 7.

Ophiopogon japonica

Mondo Grass

Evergreen, 2 inch grass-like foliage, lilac flowers that become bright blue berries. Zone 5. Partial sun to shade.

Ophiopogon japonica 'Nana'

Dwarf Mondo Grass

Bright cream and green blades with lilac flowers and blue berries to 4 inches. Partial shade to sunny spot. Zone 7.

Ophiopogon japonica 'Pam Harper'

Variegated Dwarf Mondo

Dark green 6 inch foliage with blue berries. Best in partial shade.

Ophiopogon planiscapus

Mondo Grass

Black blades with lilac flowers and blue berries to 8 inches. Best in partial shade.

Ophiopogon planiscapus 'Nigrescens'

Black Mondo Grass

Yellow flowers on spiny foliage to 6 inches. Best in well-drained soil and Sun. Zones 4-11.

Opuntia polyacantha

Prickly Pear Cactus

Fragrant, edible herb with large purple flowers to 2 ft. Attracts bees and hummingbirds. Sun. Zone 7.

Origanum laevigatum 'Hopley's'

Hopley's Marjoram

Bright yellow-green foliage and white flowers. Groundcover or as an edible herb. Sun.

Origanum vulgare 'Aureum'

Golden Oregano

Intensely fragrant, compact, edible foliage. Mostly white flowers June-Oct. Best in sun. Zone 4-8.

Origanum vulgare ssp hirtum

Pizza Oregano

Evergreen with tiny white fragrant flowers in spring. Deer-proof. 3-8 ft. Sun-partial sun. Zones 7.

Osmanthus delaveii 'Baki Kasapligil'

Turkish Sweet Olive

Naturalizes easily. Pink flowers in spring. Bright green foliage with pink undersides. Best in shade. Zones 7-9.

Oxalis oregana

Oregon Wood Sorrel

Large purple triangular foliage in threes to 6 inches. White flowers sit above foliage. Best in partial shade.

Oxalis triangularis

Purple Sorrel