O
Obolaria virginica (Virginia Pennywort)
Great Smoky Mountains (School House Gap Tr.), Gatlinburg, TN
#6853 Virginia Pennywort Specimen (Apr 11, 2015) 3
  Larger

Ochna serrulata (Mickey Mouse Bush)
Manuka State Park and Natural Area, Captain Cook, HI
#6202 Mickey Mouse Bush Specimen in Fruit (Sep 18, 2012) 3
  Larger

#6203 Mickey Mouse Bush in Fruit Close Up (Sep 18, 2012) 3
  Larger

#6899 Mickey Mouse Bush with Developing Seeds (Mar 23, 2019) 3
  Larger

#6898 Mickey Mouse Bush in Bloom (Mar 23, 2019) 3
  Larger

Oclemena acuminata (Whorled Wood Aster)
Acadia National Park, Ellsworth, ME
#3237 Whorled Wood Aster Close-up (Oct 06, 2004) 2
  Larger

Cape Breton Highlands National Park, Ingonish Beach, NS
#3736 Berries and Asters on the Headlands (Sep 03, 2005) 2
  Larger

Oclemena nemoralis (Bog Aster)
Cape Breton Highlands National Park, Ingonish Beach, NS
#3750 Bog Aster Specimen (Sep 04, 2005) 2
Oenothera biennis (Common Evening Primrose)
Lake in the Hills Fen, Lake in the Hills, IL
#345 Biennial Evening Primrose Emerging from Goldenrod (Aug 25, 2015) 3
  Larger

#505 Japanese Beetles on Evening Primrose (Aug 17, 2019) 3
  Larger

#343 Biennial Evening Primrose Close Up (Aug 23, 2006) 3
  Larger

#5283 Soldier Beetles on Biennial Evening Primrose (Aug 15, 2016) 3
  Larger

Oenothera caespitosa (Tufted Evening Primrose)
Tonto NF Superstition Wilderness Area, Apache Junction, AZ
#4641 Tufted Evening Primrose in Morning Light (Mar 28, 2009) 4
  Larger

#1555 Tufted Evening Primrose Aging to Pink (Mar 26, 2011) 2
  Larger

Dead Horse Ranch State Park, Cottonwood, AZ
#6021 Tufted Evening Primrose Close-up (Apr 21, 2012) 3
  Larger

Oenothera clelandii (Sand Evening Primrose)
Nachusa Grasslands, Nachusa, IL
#652 Sand Evening Primrose Specimen (Jun 28, 2006) 2
  Larger

Illinois Beach State Park, Zion, IL
#651 Sand Evening Primrose (Jul 10, 2000) 2
Oenothera deltoides (Dune Evening Primrose)
Anza-Borrego Desert Henderson and Coyote Cyn, Borrego Springs, CA
#2891 Dune Evening Primrose Close-up (Feb 20, 2004) 2
  Larger

#1482 Dune Evening Primrose Large Specimen (Jan 16, 2005) 2
  Larger

#3312 Flowers Along Henderson Canyon Road (Jan 31, 2005) 2
  Larger

#2890 Dune Evening Primrose and Sand Verbena (Feb 20, 2004) 2
  Larger

Anza-Borrego Desert, Borrego Springs, CA
#3322 Dune Evening Primrose with Pink Blush (Feb 01, 2005) 3
  Larger

#3321 Tower of Dune Evening Primrose (Feb 01, 2005) 3
  Larger

#3315 Henderson Canyon Road Wildflowers at Dawn (Feb 01, 2005) 3
  Larger

Oenothera filiformis (Longflower Beeblossom)
Wolf Road Prairie, Westchester, IL
#3197 Longflower Beeblossum Close-up (Aug 22, 2004) 3
  Larger

Oenothera flava ssp. taraxacoides (Dandelion Evening Primrose, Yellow Evening Primrose)
Tonto NF Superstition Wilderness Area, Apache Junction, AZ
#4546 Dandelion Evening Primrose Specimen (Mar 02, 2008) 2
  Larger

Oenothera grandis (Showy Evening Primrose)
Wichita Mountains NWR, Lawton, OK
#5953 Showy Evening Primrose Close-up (Mar 28, 2012) 3
  Larger

Oenothera pallida
Capitol Reef NP Notom and Burr Trail Roads, Torrey, UT
#6544 Pale Evening Primrose Close-up (Sep 29, 2013) 3
  Larger

Oenothera primiveris (Desert Evening Primrose)
Dead Horse Ranch State Park, Cottonwood, AZ
#6015 Desert Evening Primrose Nestled in Grass (Apr 19, 2012) 3
  Larger

Big Bend National Park East Side, Alpine, TX
#4226 Desert Primrose in a Mat of Small-flowered Milkvetch (Mar 04, 2007) 3
  Larger

Oenothera serrulata (Toothed Evening Primrose)
Lake in the Hills Fen, Lake in the Hills, IL
#232 Toothed Evening Primrose Close Up (Jun 13, 2006) 3
  Larger

#224 Toothed Evening Primrose (Jun 13, 2006) 3
  Larger

Oenothera suffrutescens (Scarlet Beeblossom)
Dead Horse Ranch State Park, Cottonwood, AZ
#6188 Scarlet Beeblossom Specimen (Apr 17, 2012) 3
  Larger

#3609 Scarlet Beeblossom Close-up (Apr 17, 2012) 3
  Larger

Oenothera villosa (Hairy Evening Primrose)
Blacks Creek Road, Boise, ID
#438 Hairy Evening Primrose Specimen (Jul 05, 2014) 3
  Larger

Olsynium douglasii (Grass Widows)
Payette NF, Scabland Sagebrush Site, Council, ID
#6077 Grass Widows Specimen (May 08, 2012) 3
  Larger

Onoclea sensibilis (Sensitive Fern)
Lake in the Hills Fen, Lake in the Hills, IL
#152 Sensitive Fern Frond (Jun 10, 1999) 2
  Larger

#7172 Michigan Lilies in a Sedge Meadow (Jul 15, 2020) 3
  Larger

Shadow (Boot) Lake, Florence, WI
#880 Lake Shore with Abundant Diverse Flora (Jul 22, 2017) 3
  Larger

Toy Lake Swamp SNA, Manitowish Waters, WI
#6996 Marsh Bellflower Supported by Sensitive Fern (Jul 21, 2019) 3
  Larger

#7002 Eyed-Brown Basking on Sensitive Fern (Jul 21, 2019) 3
  Larger

Oplopanax horridus (Devil's Club)
Hatcher Pass, Palmer, AK
#5038 Devil's Club in Flower (Jun 26, 2009) 3
  Larger

Opuntia basilaris (Beavertail Cactus)
Kofa National Wildlife Refuge, Quartzsite, AZ
#3493 Beavertail Cactus Flower and Bud Close Up (Mar 20, 2005) 2
Anza-Borrego Desert, Borrego Springs, CA
#3432 Beavertail Flower Close-up (Mar 12, 2005) 2
  Larger

#3024 Large Beavertail Cactus with Over Twenty Blossoms (Mar 21, 2017) 4
  Larger

#5383 Anza Borrego at its Best (Mar 21, 2017) 4
  Larger

#3026 Beavertail Cactus Portrait (Apr 13, 2004) 2
Anza-Borrego Desert Cool Canyon, Borrego Springs, CA
#3587 Beavertail Cactus in Cool Canyon (Apr 12, 2005) 2
#3431 Beavertail Cactus Flower and Buds (Apr 12, 2005) 3
  Larger

Anza-Borrego Desert Piedras Grandes, Ocotillo, CA
#5389 Beavertail Cactus and Brittlebush on Massive Boulders (Mar 17, 2017) 4
  Larger

Opuntia engelmannii (Desert Prickly-Pear)
Tonto NF Hieroglyphics Canyon Trail, Gold Canyon, AZ
#5995 Desert Prickly-Pear Cactus Flower Close-up (Apr 05, 2012) 3
  Larger

Opuntia fragilis (Brittle Prickly-Pear)
Quincy Bluff (TNC), Lake Delton, WI
#1123 Brittle Prickly Pear Cactus (Aug 20, 2000) 2
Opuntia humifusa (Devil's-tongue, Eastern Prickly-Pear)
Thomson-Fulton Sand Prairie, Fulton, IL
#666 Eastern Prickly Pear Specimen (Jun 16, 2006) 2
Shawnee NF -- Garden of the Gods, Mitchellsville, IL
#957 Eastern Prickly-Pear Cactus with Fruit (Nov 03, 2014) 3
  Larger

Nachusa Grasslands, Nachusa, IL
#687 Eastern Prickly Pear Cactus Flower and Spines (Jun 20, 2008) 4
  Larger

#688 Eastern Prickly Pear Cactus on Sandstone Outcrop (Jun 20, 2008) 4
  Larger

#2325 Metallic Green Bee on Prickly Pear Cactus Flower (Jun 28, 2006) 2
  Larger

#2326 Eastern Prickly-Pear Cactus Flower Close-up (Jun 28, 2006) 2
Illinois Beach State Park, Zion, IL
#685 Eastern Prickly Pear Flower and Bud (Jun 30, 2007) 2
  Larger

#631 Harvestman on Prickly Pear Flower (Jul 04, 2006) 3
  Larger

#668 Prickly Pear Cactus and Beetle (Jul 10, 2000) 3
  Larger

#669 Prickly Pear Cactus and Grasshopper (Jul 10, 2000) 3
  Larger

Opuntia littoralis (Western Prickly-Pear)
Caspers Wilderness Park, San Juan Capistrano, CA
#3543 Coast Prickly Pear Cactus Flower and Pad (Apr 04, 2005) 3
  Larger

#5400 Coast Four O'Clocks Backed by Prickly Pear Cactus (Mar 20, 2017) 4
  Larger

Opuntia macrocentra var. macrocentra (Santa Rita Prickly-Pear)
Big Bend National Park Rio Grande Vlg Area, Alpine, TX
#2843 Desert Landscape with Santa Rita Prickly Pear (Dec 27, 2003) 2
  Larger

Opuntia macrorhiza (Twist-Spine Prickly-Pear)
Thomson-Fulton Sand Prairie, Fulton, IL
#2294 Burned Sand Prairie (Apr 15, 2016) 2
  Larger

#667 Prickly Pear Cactus Flower (Jun 16, 2006) 3
  Larger

#1476 Twist-Spine Prickly-Pear Cactus with Juvenile Katydid (Jul 02, 2015) 3
  Larger

#2295 Burned Plains Prickly-Pear Cactus (Apr 15, 2016) 2
  Larger

Lost Mound Unit of Upper Mississippi River NWR, Savanna, IL
#5448 Bee in Prickly Pear Cactus Flower (Jun 26, 2017) 3
  Larger

Opuntia polyacantha (Hair-spine Prickly-Pear, Plains Prickly-Pear)
Virgin River Canyon Recreation Area, Littlefield, AZ
#4678 Hair-spine Prickly Pear Cactus Specimen (Apr 11, 2009) 2
  Larger

#4677 Hair-spine Prickly Pear Cactus with Creosote Bush (Apr 11, 2009) 3
  Larger

Theodore Roosevelt National Park, Medora, ND
#6645 Great Plains Prickly Pear Cactus Close-up (Jun 28, 2014) 3
  Larger

#6633 Plains Prickly Pear Cactus Flower and Pads (Jun 27, 2014) 4
  Larger

Orchidaceae sp. (Cultivated Hybrid Orchid)
Hawaii Tropical Botanical Garden, Papaikou, HI
#4432 Pink Spotted Orchids and Ferns (Jan 15, 2008) 3
  Larger

#4430 Orchids and Ferns (Jan 15, 2008) 3
  Larger

#4425 Red Orchid in Purple Foliage (Jan 15, 2008) 3
  Larger

#4433 Tropical Orchid Pair (Jan 15, 2008) 3
  Larger

Origanum vulgare (Oregano)
Lake in the Hills Fen, Lake in the Hills, IL
#2272 Oregano Specimen (Jul 16, 2021) 3
  Larger

Orthilia secunda (Sidebells Wintergreen)
Mt. Rainier National Park Summerland Trail, White River Entrance, WA
#511 Sidebells Wintergreen Specimen (Jul 30, 2014) 2
  Larger

Patterson Hemlocks State Natural Area, Woodruff, WI
#5484 Sidebells Wintergreen in Context (Jul 02, 2021) 3
  Larger

Orthosiphon aristatus (Cat's Whiskers)
Hawaii Tropical Botanical Garden, Papaikou, HI
#7040 Cat's Whiskers Specimen (Jan 15, 2008) 3
  Larger

Osmorhiza longistylis (American Sweet Cicely)
David Schwaegler's Home, Lake in the Hills, IL
#277 American Sweet Cicely Close-up (May 27, 2013) 3
  Larger

#7094 American Sweet Cicely in the Rain (May 15, 2020) 3
  Larger

Osmunda cinnamomea (Cinnamon Fern)
Indiana Dunes National Lakeshore, Chesterton, IN
#2492 Cinnamon Fern Fiddlehead Riot (May 11, 2016) 3
  Larger

Osmunda claytoniana (Interrupted Fern)
Mississippi Palisades S.P., Savanna, IL
#2356 Fertile Frond of Interrupted Fern (May 14, 2014) 4
  Larger

Acadia National Park, Ellsworth, ME
#3231 Interrupted Fern Specimen (Oct 07, 2004) 2
  Larger

Baraga County, L'Anse, MI
#1977 4. Descending to Sturgeon Falls -- Interrupted Fern by Path (Oct 08, 2015) 3
  Larger

Osmunda regalis (Royal Fern)
Petit Jean State Park, Morrilton, AR
#1561 Royal Fern by Creek Edge (Apr 06, 2011) 2
  Larger

#1562 Royal Fern Fertile Frond (Apr 06, 2011) 2
  Larger

Pine Rock Nature Preserve, Oregon, IL
#1734 Royal Fern Frond in Fall Color (Sep 22, 2015) 3
  Larger

Indiana Dunes National Lakeshore, Chesterton, IN
#2413 Royal Fern Fiddleheads (May 11, 2016) 3
  Larger

Quincy Bog, Rumney, NH
#5787 Royal Fern with Fertile Frond (Jun 09, 2011) 4
  Larger

Osteomeles anthyllidifolia (Hawaii Hawthorn, Hawaiian Rose, Ulei)
South Kona Coast of the Big Island, Captain Cook, HI
#6894 Hawaiin Rose Close-up (Mar 31, 2019) 3
  Larger

#6893 Hawaiian Rose Specimen (Mar 31, 2019) 3
  Larger

#6928 Bee on Hawaiian Rose (Mar 30, 2019) 3
  Larger

Manuka State Park and Natural Area, Captain Cook, HI
#6204 Hawaiian Rose in Fruit (Sep 18, 2012) 2
  Larger

Othocallis siberica (Siberian Squill)
David Schwaegler's Home, Lake in the Hills, IL
#7081 Siberian Squill Fill the Yard (Apr 07, 2020) 3
  Larger

#5405 Bloodroot and Squill in the Rain (Apr 10, 2017) 3
  Larger

#1192 Bloodroot and Squill (Apr 12, 2006) 3
  Larger

#1180 Siberian Squill Close-up (Mar 31, 2016) 4
  Larger

#2239 Siberian Squill Portrait (Mar 31, 2016) 3
  Larger

#2223 Siberian Squill -- a Mass of Blue (Mar 29, 2016) 3
  Larger

#5594 Siberian Squill in Melting Snow (Mar 23, 2020) 3
  Larger

#5593 Field of Siberian Squill in Snow (Apr 15, 2018) 3
  Larger

Oxalis montana (Common Wood Sorrel)
Adirondack Park, Lake Clear, NY
#782 Common Wood Sorrel Close-up (Jun 20, 1999) 2
  Larger

Oxalis oregana (Redwood Sorrel)
Prairie Creek Redwoods Miner's Ridge Loop, Orick, CA
#3136 Redwood Sorrel Flower and Leaves (May 17, 2009) 4
  Larger

Oxalis stricta (Yellow Wood Sorrel, Sourgrass)
Wichita Mountains NWR, Lawton, OK
#6006 Common Yellow Wood Sorrel Specimen (Mar 31, 2012) 2
  Larger

Oxalis violacea (Violet Wood Sorrel)
Grandview Prairie, Columbus, AR
#3911 Violet Wood Sorrel from a Low Angle (Mar 16, 2006) 3
  Larger

Ouachita NF, Albert Pike Winding Stairs Trail, Langley, AR
#4329 Violet Wood Sorrel in a Bed of Leaves (Mar 29, 2007) 4
  Larger

Devil's Knob Area, Melbourne, AR
#3971 Violet Wood Sorrel in Full Bloom (Mar 29, 2006) 2
  Larger

Petit Jean State Park, Morrilton, AR
#1560 Violet Wood Sorrel Flowers and Leaves (Apr 06, 2011) 4
  Larger

Dixie Briggs Fromm, Algonquin, IL
#6589 Violet Wood Sorrel Specimen (May 10, 2014) 3
  Larger

#5609 Violet Wood Sorrel Portrait (May 10, 2018) 3
  Larger

#5608 White Blue-eyed Grass with Violet Wood Sorrel Buds (May 10, 2018) 3
  Larger

Hennig/Kloempken Marsh and Savanna, Huntley, IL
#2069 Violet Wood Sorrel with Fly (May 26, 2002) 3
  Larger

Lake in the Hills Fen, Lake in the Hills, IL
#7291 Violet Wood Sorrel on Burned Ground (May 11, 2021) 3
  Larger

Nachusa Grasslands, Nachusa, IL
#464 Late-Blooming Violet Wood Sorrel (Aug 03, 2016) 3
  Larger

Oxydendrum arboreum (Sourwood)
Red River Gorge Tunnel Ridge Road, Stanton, KY
#5853 Sourwood with Seeds in Fall Color (Oct 21, 2011) 3
  Larger

Lake Jocassee Jumping Off Rock, Liberty, SC
#5880 Sourwood in Fall Color (Oct 29, 2011) 3
  Larger

Oxypolis rigidior (Cowbane)
Lake in the Hills Fen, Lake in the Hills, IL
#1232 Cowbane Umbel Close-up (Aug 22, 2011) 3
  Larger

#553 Cowbane Speciman (Aug 22, 2011) 3
  Larger

Kettle Moraine Low Prairie SNA, Eagle, WI
#5273 August Prairie with Diversity of Wildflowers (Aug 09, 2016) 3
  Larger

Genesee Oak Opening, North Prairie, WI
#5272 Cowbane Trio of Umbels (Aug 09, 2016) 3
  Larger

Oxytropis campestris (Field Locoweed)
Alaska Highway -- Yukon Highway 1, Haines Junction, YT
#5001 Lake Kluane (clue-WHA-nee) Roadside Covered with Wildflowers (Jun 19, 2009) 3
  Larger