Verbena stricta
hoary vervain [Blooms: Jun-Jul]
Hoary vervain (Verbena stricta) flowers. Left: a series of hoary vervain flower spikes with flower buds on the more distal parts of the spike, open flowers more basally, and maturing fruit beneath the open blooms. Right: the region of a flower spike with the flowers in full bloom. The two lateral flower lobes are the largest, one or both lower lobes are smaller and have a small notch in their tips, while upper lobe is about the same size but lacks a notch. The reproductive structures are not visible externally. Note the dense cover of hairs on the leaves in the lower part of the image.
Hoary vervain flower spikes are 1-8″ long; they are crowded with buds and bluish violet to lavender flowers 1/2″ across that open sequentially from the bottom of the spike to the top; below the open flowers are maturing fruits. Individual flowers are tubular, 1/2″ long and across, with a grayish green to reddish-purple, hairy calyx sporting five narrow teeth. The tubular, bluish violet to lavender corolla, twice the length of the calyx, abruptly flares into five ovate lobes (“petals”); the two lateral lobes are the largest, while the lower lobe(s) has/have a notched tip. Hidden in the tubular corolla are four recessed stamens with yellow anthers and a single, short green style. The fruits consist of four nutlets held in the remnants of the calyx.
Hoary vervain (Verbena stricta) stems and leaves. Left: a hoary vervain stem with a dense coat of short, white hairs. The opposite leaves are closely spaced along the stem; they, too, are densely hairy. Right: a stem leaf of hoary vervain showing the upper surface of the leaf (top image) and the underside of the same leaf (bottom image). Note the very short petiole.
Hoary vervain is a native perennial up to 3.5 feet tall, branching occasionally. The stems are green to reddish-purple, square in section (four-angled), and densely covered with long, white hairs. The leaves are opposite, sessile, ovate to egg-shaped, up to 4″ long and 3″ across, with coarsely serrated (sometimes doubly serrated) margins. There is only a stub (less than 5 mm) of a petiole or none at all, and the leaves are covered with fine white hairs (especially the undersides). (Thus, the name “hoary.”)
Two hoary vervain (Verbena stricta) plants growing at 63rd St. Beach. The plant on the left is growing in the back dunes; the plant on the right is growing high on the beach itself.
Hoary vervain is a native perennial up to 3.5 feet tall, branching occasionally. The stems are green to reddish-purple, square in section (four-angled), and densely covered with long, white hairs. The leaves are opposite, sessile, ovate to egg-shaped, up to 4″ long and 3″ across, with coarsely serrated (sometimes doubly serrated) margins. There is only a stub (less than 5 mm) of a petiole or none at all, and the leaves are covered with fine white hairs (especially the undersides). (Thus, the name “hoary.”) Flower spikes are 1-8″ long; they are crowded with buds and bluish violet to lavender flowers 1/2″ across that open sequentially from the bottom of the spike to the top; below the open flowers are maturing fruits. Individual flowers are tubular, 1/2″ long and across, with a grayish green to reddish-purple, hairy calyx sporting five narrow teeth. The tubular, bluish violet to lavender corolla, twice the length of the calyx, abruptly flares into five ovate lobes (“petals”); the two lateral lobes are the largest, while the lower lobe(s) has/have a notched tip. Hidden in the tubular corolla are four recessed stamens with yellow anthers and a single, short green style. The fruits consist of four nutlets held in the remnants of the calyx.
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![Evening primrose — clusters of yellow flowers occur at the apex of the plant. The flowers are 1-2" across, with four 1/2-1" long green sepals strongly reflected over a long (3/4-2"), green, cylindrical floral tube (the ovary is located just above the leaf axil), four heart-shaped yellow petals, eight stamens, and a single style with an X-shaped stigma. The sepals typically remain connected (in pairs) along one edge until the flower opens. The seedpods develop within the ovary (the base of the elongate floral tube); they are hairy, urn-shaped with rounded edges, and have four or eight small lobes on the apex. The seeds are claimed to remain viable in the soil for up to 70 years. The flowers open at dusk and close early in the day. — — — There are (at least) three evening primroses in Jackson Park — common evening primrose (Oenothera biennis), northern evening primrose (Oenothera parviflora), and hairy evening primrose (Oenothera villosa). They are easily confused with each other. (Judging by the conflicts between the accounts on Illinois Wildflowers [https://www.illinoiswildflowers.info/], Minnesota Wildflowers [https://www.minnesotawildflowers.info/], and Missouri Plants [http://www.missouriplants.com/], even the experts are confused.) All three species have yellow flowers with an X-shaped stigma, reflected sepals, petals with a small notch in their apex, stems that may be red or green, and lance-shaped leaves with short, widely-spaced teeth. Northern evening primrose is distinguished by (1) the presence of a knob or ridge at the tip of each sepal which the other two species lack (2) a seed capsule with four robust, flaring lobes with rounded tips at the apex of the seed capsule, and (3) a stigma that is very robust and almost fills the opening of the flower. Northern evening primrose has green to yellowish-green sepals. Hairy evening primrose (often but not always) has (1) striped or reddish-tinged sepals (check the buds where this character is often easier to see), (2) flowers that turn orange as they begin to senesce (although the reliability of this character is uncertain), and (3) always has glandular hairs covering the ovary that have "pimple-like" bright-red bases; these red pimples may also occur on the stems. All three species are somewhat similar to prairie sundrop (O. pilosella); the latter has very hairy stems and leaves, and translucent lines that radiate from the base of the petals in the flowers.](https://jacksonparkwildflowers.info/wp-content/uploads/2025/03/Oenothera_biennis-1t-300x300.jpg)
![Northern evening primrose flowers are 3/4-1.5" across, have four yellow, heart-shaped petals, eight yellow stamens, and a cross-shaped stigma on a modest style; the stamens are as long or longer than the petals and the stigma is nearly fills the floral opening. At the base of the flower are four sepals 1/2-1" long, that bend back along the 3/4-1.5" long floral tube as the flower develops with pairs of sepals attached along one edge until the flower opens. Only northern evening primrose with a distinct ridge or knob near the tips of the sepals. The seed capsule develops from the ovary; it is 3/4-1.5" long, cylindrical but tapering slightly towards the tip, with four robust, flaring lobes at the tip. — — — There are (at least) three evening primroses in Jackson Park — common evening primrose (Oenothera biennis), northern evening primrose (Oenothera parviflora), and hairy evening primrose (Oenothera villosa). They are easily confused with each other. (Judging by the conflicts between the accounts on Illinois Wildflowers [https://www.illinoiswildflowers.info/], Minnesota Wildflowers [https://www.minnesotawildflowers.info/], and Missouri Plants [http://www.missouriplants.com/], even the experts are confused.) All three species have yellow flowers with an X-shaped stigma, reflected sepals, petals with a small notch in their apex, stems that may be red or green, and lance-shaped leaves with short, widely-spaced teeth. Northern evening primrose is distinguished by (1) the presence of a knob or ridge at the tip of each sepal which the other two species lack (2) a seed capsule with four robust, flaring lobes with rounded tips at the apex of the seed capsule, and (3) a stigma that is very robust and almost fills the opening of the flower. Northern evening primrose has green to yellowish-green sepals and is the only one of the three evening primroses to (sometimes) have reddish color on some or all of the midvein of the leaves. Hairy evening primrose (often but not always) has (1) striped or reddish-tinged sepals (check the buds where this character is often easier to see), (2) flowers that turn orange as they begin to senesce (although the reliability of this character is uncertain), and (3) always has glandular hairs covering the ovary that have "pimple-like" bright-red bases; these red pimples may also occur on the stems. All three species are somewhat similar to prairie sundrop (O. pilosella); the latter has very hairy stems and leaves, and translucent lines that radiate from the base of the petals in the flowers.](https://jacksonparkwildflowers.info/wp-content/uploads/2025/03/Oenothera_parviflora-1t-300x300.jpg)
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