Transformational Gardening

Common Evening Primrose (Oenothera biennis): Images

Date Location Notes Images
September 5, 2011 Southeastern, New Hampshire The plants I encountered were 5 to 7 feet tall. In New Hampshire, there are only a few species of Evening Primrose that are very tall (over 4 feet tall).
  • Northern Evening Primrose (Small Flower Evening Primrose) (Oenothera parviflora): Very similar to Common Evening Primrose. The main difference is that the two sepal tip appendages on Common Evening Primrose begin at the apex of the sepal. For Northern Evening Primrose, the two sepal tip appendages begin before the apex of the sepal. Click on first picture in 2nd row for details.
  • Redsepal Evening Primrose (Oenothera glazioviana): The flower of Redsepal Evening Primrose is much bigger -- flower petals being 3-5 cm tall and sepals are red. Often seen in gardens, sparingly escaped into the wild.
  • Oakes’ Evening Primrose (Oenothera oakesiana) (Synonym: Oenothera parviflora var. angustissima): Oakes Evening Primrose is considered a variation of Northern Evening Primrose (Oenothera parviflora) (see above). Therefore, the sepal tip appendages begin before the apex of the sepal. It has short, stiff white/gray and appressed hairs without having glandular hairs.
  • Common Evening Primorose (Oenothera biennis): This plant. Notice that the two sepal appendages grow out of the apex of the sepal.
  • Hairy Evening Primrose (Oenothera villosa) (Synonyms: Oenothera biennis var. canescens, Oenothera strigosa): Hairy Evening Primrose is often considered a variation of Common Evening Primorose (Oenothera biennis). It is densely-covered with grayish stiff hairs that can either be short or long and has few or no gland-tipped hairs.
In order to limit the list of Evening Primrose to the above five possibilities, rather than using the plant height, I used the Key provided in the book, Manual of Vascular Plants of Northeastern United States and Adjacent Canada. This plant has roundly 4-angled fruit (not sharply 4-angled fruit), yellow flowers and the fruit is thickest at the base and tapers (not linear).

I took quite a few pictures and measurements of this plant. You can see that the leaves are around 12 cm long and 3.8 cm wide. The seeds are approximately 1.2 mm long. The flower petals are 1.8 cm high and approximately the same width. The sepals + sepal appendages are nearly 3 cm long. The sepal appendages are 5 mm long. This plant was 7-1/2 feet tall!
Date Location Notes Images
May 2, 2012 Southeastern, New Hampshire The only reason I know this is Common Evening Primrose Oenothera biennis is that I found it the same exact place as the identification I made on September 5, 2011 (see above). It is close to producing a stalk.
Date Location Notes Images
May 9, 2012 Southeastern, New Hampshire