Oenothera biennis (Common evening primrose)

Oenothera biennis L.

Common evening primrose

Kingdom	Plantae	Plants, but not fungi, lichens, or algae
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Rosidae	Roses, legumes, proteas, dogwoods, hydrangeas, mistletoes, euphorbias, grapes, many more
Order	Myrtales	Includes myrtles, leadwoods, loosestrifes, pomegranates, evening primroses, many others
Family	Onagraceae	Willowherb/evening primrose family
Genus	Oenothera	Derivation uncertain: 1. Greek ονος θηρας (onos theras), or “donkey catcher.” 2. Or οινος θηρας (oinos theras), “wine seeker.” 3. Or Latin oenothera, “a plant whose juices may cause sleep”
Species	biennis	“Completing its life cycle over two growing seasons” (biennial)

About plant names...

Common evening primroses are indeed common, native throughout much of the world and found everywhere except deserts in North America. Evening primroses are so-called because their flowers open at night.

Identification: Plants are 3-5' (91-152 cm) tall, rarely up to 8' (2.4 m). Usually composed of a single central stem, plants sometimes branch out multiply if there is enough light, looking almost shrublike. Stems are light green or red, with short whitish hairs. Leaves are lanceolate—long, thin, sharp-tipped ovals 1¾-8" (5-20 cm) × ⅜-⅞" (1-2.5 cm), light or olive green. Plants have a two year (“biennial”) life cycle. In the first year, the leaves form a rosette at the base of the plant. In the second, they are arranged around the stem in a spiral pattern. Flowers are pale to bright yellow, with four petals, up to 2" (5 cm) across; they open at night. They are hermaphrodites—each flower has both male and female structures. Under ultraviolet light, a “nectar guide” appears: landing lights, if you will, for pollinators such as bees. Fruits are capsules ¾-1½" (2-4 cm) × ⅛-³/₁₆" (4-6 mm).

Online References:

Oenothera biennis on Missouriplants.com

Oenothera biennis at Illinois Wildflowers

Oenothera biennis at the Lady Bird Johnson Wildflower Center

Oenothera biennis on Plants for a Future, a resource and information centre for edible and otherwise useful plants

Oenothera biennis on spes.vt.edu

Oenothera biennis on Wildflowers of the United States

Oenothera biennis from the Jepson Manual

8/2/2009 · Gordon & Kathy’s, Prospect, Maine
≈ 3½ × 5" (9.6 × 13 cm) ID is uncertain

8/6/2009 · Nashua River Rail Trail, Groton, Massachusetts
≈ 9 × 7" (22 × 18 cm) ID is uncertain

8/11/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 3½ × 3" (9.5 × 7.9 cm)

9/4/2017 · Oxbow National Wildlife Refuge, Ayer, Massachusetts
≈ 4½ × 3" (11 × 8.4 cm)

8/8/2009 · Nashua River Rail Trail, Groton, Massachusetts
≈ 4 × 5" (10 × 13 cm) ID is uncertain

8/4/2009 · Near Nashoba Hospital, Ayer, Massachusetts
≈ 4½ × 4½" (12 × 11 cm) ID is uncertain

9/11/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 4½ × 3½" (11 × 9.2 cm)

8/2/2009 · Gordon & Kathy’s, Prospect, Maine
≈ 3 × 4" (7.5 × 9.9 cm) ID is uncertain

9/4/2017 · Oxbow National Wildlife Refuge, Ayer, Massachusetts
≈ 3½ × 5" (9.2 × 13 cm)

8/6/2009 · Nashua River Rail Trail, Groton, Massachusetts
≈ 7 × 9" (17 × 22 cm) ID is uncertain

Oenothera biennis L. ssp. caeciarum Munz

Oenothera biennis L. ssp. centralis Munz

Oenothera biennis L. var. pycnocarpa (Atk. & Bartlett) Wiegand

Oenothera muricata L.

Oenothera pycnocarpa Atk. & Bartlett

Oenothera biennis description by Thomas H. Kent, last updated 5 Oct 2021.

8/2/2009 · Gordon & Kathy’s, Prospect, Maine
≈ 2½ × 4" (7 × 9.9 cm) ID is uncertain

4/12/2012 · Nashua River Rail Trail, Groton, Groton, Massachusetts
≈ 5 × 6" (13 × 14 cm) ID is uncertain

8/6/2009 · Nashua River Rail Trail, Groton, Massachusetts
≈ 5 × 4½" (13 × 11 cm) ID is uncertain

The primrose moth (Schinia florida) on his preferred haunt. · 8/18/2013 · Bemis Road, Townsend, Massachusetts
≈ 2½ × 2" (6.2 × 5.8 cm)

9/19/2010 · Nashua River Rail Trail, Hollis, New Hampshire
≈ 14 × 9" (35 × 23 cm) ID is uncertain

7/28/2009 · Near Nashua River Boat Ramp, Groton, Massachusetts
≈ 17 × 15" (44 × 39 cm) ID is uncertain

8/4/2009 · Near Nashoba Hospital, Ayer, Massachusetts
≈ 6 × 9" (14 × 22 cm) ID is uncertain

8/1/2009 · Coastal Maine Botanical Gardens, Boothbay, Maine
≈ 7 × 11" (17 × 26 cm) ID is uncertain

9/10/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 6 × 4" (15 × 10 cm)

8/19/2018 · Townsend Wildlife Management Area, Townsend, Massachusetts
≈ 3 × 3½" (8.1 × 9.0 cm)

7/28/2009 · Near Nashua River Boat Ramp, Groton, Massachusetts
≈ 3½ × 4" (9 × 10 cm) ID is uncertain

8/8/2009 · Nashua River Rail Trail, Groton, Massachusetts
≈ 8 × 6" (20 × 15 cm) ID is uncertain

The visitor is a primrose moth (Schinia florida). · 8/4/2009 · Near Nashoba Hospital, Ayer, Massachusetts
≈ 4½ × 4" (12 × 10 cm) ID is uncertain

Range:

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