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)
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).
7/28/2009 · Near Nashua River Boat Ramp, Groton, Massachusetts · ≈ 4 × 6″ (10 × 15 cm) ID is uncertain
8/8/2009 · Nashua River Rail Trail, Groton, Massachusetts · ≈ 9 × 6″ (23 × 15 cm) ID is uncertain
The visitor is a primrose moth (Schinia florida). · 8/4/2009 · Near Nashoba Hospital, Ayer, Massachusetts · ≈ 7 × 11″ (18 × 28 cm) ID is uncertain