August 7, 2025

I’m seeing this biennial, herbaceous plant, now in many places along my dirt road coming up the mountain. It’s Common Evening Primrose (Oenothera biennis), which grows quite tall, sometimes to 6 feet.

The Evening Primrose flowers look nearly identical to Sundrops (Oenothera fruticosa) but that plant blooms in the spring, while Common Evening Primrose blooms later in the summer. And the height is different in Sundrops as well, that plant might grow to a height of just 3 feet.

Common Evening Primrose opens its flowers in the evening and they stay open through the night, closing by noon. While Sundrops bloom only during the day. Both plants have yellow flowers with four petals, each petal being heart shaped.

These two plants used to confuse me, but now I’ve got it straight.

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