Oenothera serrulata (Yellow Sundrops)

Plant Info
Also known as: Toothed Evening Primrose, Plains Yellow Primrose
Genus:Oenothera
Family:Onagraceae (Evening Primrose)
Life cycle:perennial
Origin:native
Habitat:sun; dry sandy or rocky soil; prairies, rock outcrops, bluffs, dunes
Bloom season:June - August
Plant height:1 to 2 feet
Wetland Indicator Status:none
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: 4-petals

[photo of flower] Single yellow flowers in the upper leaf axils with 4 rounded petals ¼ to ½ inch (5 to 12+ mm) long, often wrinkled like crumpled tissue paper, with wavy edges that are sometimes a bit ragged, and a rounded notch at the tip. In the center are 8 yellow stamens surrounding a stigma with 4 disc-shaped lobes. The 4 sepals are shorter than the petals, triangular to egg-shaped with a prominent mid-rib, and reflexed down at bloom time. Flowers are stalkless but sit on top of a hairy, cylindrical ovary about 3/8 inch long that resembles a stalk.

Leaves and stems: Leaf attachment: alternate Leaf type: simple

[photo of leaves] Leaves are alternate, narrowly oblong, linear, or widest above the middle, ½ to 3½ inches (to 9 cm) long, up to 3/8 inch (1 cm) wide, stalkless or nearly so, short-hairy on the underside, usually with small, sharp teeth around the edges, occasionally toothless. Stems are ascending to erect, green to brown, covered in stiff, fine hairs, single or multiple from the base, unbranched or few-branched, and woody in the lower stem.

Fruit: Fruit type: capsule/pod

[photo of fruit] Fruit is a slender, cylindrical capsule in the leaf axils, slightly tapered at both ends, up to about 1 inch (6 to 25 mm) long, covered with fine, short hairs. Inside are numerous seeds, 1 to 1.8 mm long, sharply angled.

Notes:

Yellow Sundrops, also known as Calylophus serrulatus, is common in dry prairies and rock outcrops. It is typically much shorter than the tall spiked stems of evening primroses and has much narrower leaves. Another distinction with this species is that it blooms during the day where most Oenothera flowers open in afternoon or evening, for pollination by night-flying insects. It does great in a garden and has a fairly long bloom period. Personally, I was disappointed when the musical name Calylophus was dropped in favor of boring Oenothera, but at least it's in Oenothera subsection Calylophus.

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More photos

Photos by K. Chayka Ramsey and Washington counties. Photos by Peter M. Dziuk taken in Dakota and Pope counties.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Nancy - Dakota and Goodhue Counties
on: 2013-08-01 10:13:50

I see this plant in remnant sand prairies and have found it in several locations. A beautiful but somewhat inconspicuous member of our native prairie flora!

Posted by: Elizabeth
on: 2018-07-16 09:10:27

Can anyone identify the purple/blue flower in photo 6 of 8 above? I would love to grow them together, what a nice combination.

Posted by: K. Chayka
on: 2018-07-18 19:03:19

Verbena stricta, hoary vervain.

Posted by: Brett - Clay County
on: 2019-07-18 17:57:27

First time seeing this plant...In Blanket Flower SNA.

Posted by: Timothy Johnson - Hennepin County
on: 2022-06-29 10:48:03

These are doing well in a restored dry sandy prairie in Oxbow Park, Champlin, MN

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