Masked bees – Wild Things in the Garden

Violet Peaks in Shadows

Lilac blue spires of Great Blue Lobelia (Lobelia siphilitica) grace the late season garden. With vivid color and abundant resources, they lure pollinators. Their intricate, multi-lobed blooms offer both nectar and pollen.

Lobelia siphilitica enjoys moist to wet conditions in Zones 4 through 9. Fertile, loamy soil is best. Great Blue Lobelia grows in part sun to light shade. In general, the plant is one to four feet tall and has a one foot to eighteen inch spread.^2,4

This lobelia adapts to many environments. It tolerates occasional flooding making it a good candidate for the rain garden. In northern climates, with consistently moist soil, it can grow in full sun. The height varies based on the growing conditions. If under too much stress, Lobelia siphilitica gets ragged.²

In natural habitats, L. siphilitica lives in disturbed areas and high-quality habitats. It’s found in moist black soil prairies, soggy meadows near rivers, low areas along rivers, ponds, floodplains, bottomland woodlands, woodland borders, bottoms of sandstone canyons, along streams, in swamps, fens, gravelly seeps and springs, ditches, and moist areas of pastures.²

Great Blue Lobelia plants form clumps that can be divided in Spring or Fall. In my garden, seedlings thrive in areas that flood. Otherwise, it doesn’t spread aggressively.⁴

The medium to dark green foliage forms a lovely background for the L. siphilitica’s striking blooms. Its leaves alternate along Great Blue Lobelia’s stem. They are ovate to lanceolate and lightly covered with short hairs.²

Foliage can grow up to five inches long and two inches wide. The bottom leaves can have a short stem. Leaves at the top of the plant are sessile (touching) to the stem.²

Lobelia siphilitica blooms for about two months from late summer into fall. The intense blue-violet (occasionally white) flowers are packed closely on the raceme. Each blossom is an inch to one and a half inches long.²

Flowers are two-lipped. The upper lip had two lobes while the lower lip had three. The lower lip offers a landing pad for pollinators.^1,2,4

Its green calyx has five lance-shaped teeth. They are hairy, long and spreading. Individual blooms emerge from the upper leaf axils.²

Great Blue Lobelia serves numerous insects late in the growing season. The Xerces Society for Invertebrate Conservation designated it of Special Value to Native Bees and Special Value to Bumble Bees. It also Supports Conservation Biological Control according to the Xerces Society.⁶

Large to medium, long-tongued bees primarily serve as pollinators. Bumblebees (Bombus spp), Digger bees (Anthophora spp), Wool Carder Bees (Anthidium spp) and Long-horned bees (Melissodes spp and Svastra spp) all successfully pollinate this Lobelia. Additionally, these bees steal nectar from outside the flower sidestepping the pollination process.^1,2,4

L. siphilitica uses a remarkable system for pollination. The five stamens (male parts) form a ring around the style (female part). This whole grouping runs along the inside top of the flower and curls down ending with the stigma (area for pollen deposit). It appears to be one structure.¹

Lobelia flowers secrete nectar at the bottom to lure bees deep inside. Small bees can just climb down to it and drink. They may or may not get any pollen on their bodies.

Medium and large bees need to wiggle their way inside the flower. It’s a tight fit and they invariable rub against the anthers. Pollen deposits on their backs.^1,4

The weight of these bees causes several physical changes to the flower. The three lower lobes form a landing place. The bee’s weight pushes the lobes down and the style/anther structure arches down. The stigma, at the end, rubs against any pollen on the bee’s back successfully transferring it.^1,4

In addition to the medium and large bees, numerous small bees harvest nectar and pollen from Lobelia siphilitica. The Masked Bees (Hylaeus spp) and Halictid bees are frequent visitors. The Halictids include small dark sweat bees like Lasioglossum spp. and the green metallic sweat bees such as Agapostemon spp. and Augochlora spp.⁴

Augochlora pura is a stunning small bee that enjoys visiting this Lobelia. Augochlora pura means pure golden green. This metallic green sweat bee can be all green but can also have patches of copper, gold or very dark green that looks blue.⁷

With an extremely long active season, A. pura usually flies from April to October. In a warm year, you can see it from February to November. This tiny bee gathers resources from diverse flowers including Maple tree flowers (Acer spp.), the Rosaceae family (apples, strawberries, cherries, roses, etc.), the Asteraceae family (asters, goldenrods, coreopsis, etc.), milkweeds, hydrangeas, spiderworts, verbena and others.⁷

Augochlora pura has an unusual nesting strategy unlike the other Halictid bees. They nest under loose bark of fallen trees. Females glues together mud and debris from under the bark to make nesting cavities.⁷

She then gathers pollen on her hind legs and nectar. Back at the nest, the female mixes pollen with nectar and her saliva. The saliva may have antiseptic qualities.⁷

When there’s enough food in a cavity, she lays an egg. Each nest cell is lined with an impermeable lining produced by one of the bee’s glands. This lining protects the egg and developing larva from predators.⁷

Augochlora pura may have more than one generation in a growing season. The final generation is in Fall. Males and females hatch and mate.⁷

Males then die. The females continue gathering resources and eating. They build up fat to survive the long Winter hibernation. Augochlora pura females overwinter in existing cavities in fallen rotting logs or wood stumps.^4,7

Less common visitors include Ruby Throated Hummingbirds and large butterflies. Although, in my garden, I often see hummingbirds nectaring at my Great Blue Lobelia.²

I hope you’ve enjoyed this deep dive into Great Blue Lobelia (Lobelia siphilitica). I’d love to hear about your plant adventures in the garden or the wild! Please feel free to contact me with a story, comment or question!

Happy Gardening,

Mary

Bibliography:

“Great Blue Lobelia.” Accessed February 1, 2025. https://www.fs.usda.gov/wildflowers/plant-of-the-week/lobelia_siphilitica.shtml.
“Great Blue Lobelia (Lobelia Siphilitica).” Accessed February 1, 2025. https://www.illinoiswildflowers.info/wetland/plants/gb_lobeliax.htm.
“Great Blue Lobelia, Lobelia Siphilitica L.” Accessed February 1, 2025. https://friendsofeloisebutler.org/pages/plants/greatbluelobelia.html.
Holm, Heather. Bees: An Identification and Native Plant Forage Guide. Minnetonka, MN: Pollination Press LLC, 2017.
“Lobelia Siphilitica – Plant Finder.” Accessed February 1, 2025. https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=i460.
“Lobelia Siphilitica (Great Blue Lobelia) | Native Plants of North America.” Accessed February 1, 2025. https://www.wildflower.org/plants/result.php?id_plant=losi.
“The Pure Golden Green Sweat Bee.” Accessed February 1, 2025. https://www.fs.usda.gov/wildflowers/pollinators/pollinator-of-the-month/augochlora_pura.shtml.

Grist for the Bees

Purple Wheat in the garden? Indeed, that’s what Agastache means ‘agan’ much, ‘stachys’ ear of grain, from the Greek. Its flowers look like heads of wheat or rye and range from pale lavender to purple. ‘Foeniculum’, the second part of the name, means fragrant for the scented leaves. Agastache foeniculum (Fragrant or Anise Hyssop) is part of the mint family. Like Pycnanthemum virginianum (https://wildthingsinthe.garden/2023/05/31/white-goes-with-everything/), also mints, it attracts an enormous variety of bees. Fragrant Hyssop also supports numerous butterflies and skippers.

Anise Hyssop grows two to four feet tall and spreads eighteen inches to two feet. It has an upright, clump-forming habit. Anise Hyssop sports dark green, ovate to broadly lanceolate leaves up to four inches long. Almost heart shaped, the leaves are one to three inches at the base and whitish underneath. They sit opposite each other on the classic square stem of mint plants. The foliage also gives off a strong anise or licorice-like scent that gives the plant its common and Latin name.

Agastache foeniculum can begin blooming in June and continues through August. In zone 5, where I am, it doesn’t start until July. Blooms appear as three- to six-inch-long flower spikes at the end of plant stalks. The eye-catching blossoms range from pale lavender to true purple in color. Tiny flowers make up each large spike. They’re laid out in tightly packed rows although there can be gaps (think of an ear of corn). This arrangement is called verticillasters or false whorls. Each of the small flowers is tubular, 2-lipped and a 1/3’’ inch long. Unlike the leaves, the blooms have no scent.

Fragrant Hyssop plant grows best in full sun with dry to moderately moist soil. Soil moisture is not a problem if the drainage is good. Anise Hyssop is drought tolerant, more so after it is established. It spreads by rhizomes and self-seeding especially under good conditions. I have not found that this plant spreads obnoxiously. I have far fewer Anise Hyssop seedlings than Monarda fistulosa seedlings. Fragrant Hyssop may have problems with crown rot with soggy soil. Other issues include rust and powdery mildew.

Outside of cultivation, Agastache foeniculum grows in prairies, dry upland forests, plains, fields, roadsides, and other dry, open, semi-shaded areas. In the past, it served as honeybee forage in Canada and parts of the Upper Midwest. It works well in borders, wildflower gardens, herb gardens, butterfly gardens and meadows.

Agastache foeniculum and similar species inspire plant breeders around the world. Too many nativars exist to explore them all, but I thought we could look at three very different plants. Each of these was modified in a different way.

Agastache ‘Blue Fortune’ is a very popular hybrid created by crossing Agastache foeniculum with its East Asian relative, Agastache rugosa. This compact plant has longer flower spikes than the species. It blooms for an extended time because it’s bred to be sterile. ‘Blue Fortune’ is widely reported to be a pollinator magnet.

Agastache ‘Golden Jubilee’ is an older hybrid with yellow-green foliage that’s pure yellow in the Spring. The flowers are identical to the species. ‘Golden Jubilee’ received the All-American Selection Award in 2003 and is still being sold. It will self-seed with a mix of species and golden seedlings. There are mixed reports on how pollinators respond to ‘Golden Jubilee’. Some sources say bees don’t seem to ‘see’ it and others say pollinators love it.

Agastache ‘Red Fortune’ has red to pink flowers. The leaves are like the species. Pollinators don’t like this plant as much as Agastache foeniculum.

These three plants give a nice snapshot of how natives are altered and some pollinator responses. One idea is that nativars with flowers most like the species’ flowers would be most acceptable.¹ Positive reports about ‘Blue Fortune’ and ‘Golden Jubilee seem to support this idea.²

In addition, red is a special case. Bees see in the ultraviolet spectrum—from approximately 300 to 650 nm. They can’t see red although they can see reddish tones like orange. When native plants are hybridized for red flowers, bees often have trouble finding them.^1,3

But wait! There’s an exception. Red flowers can have ultraviolet “nectar guides” which the bees see perfectly well. Plants use these guides to “direct” the pollinators to the nectar reward and encourage pollination.³

It’s hard to say if a red native hybrid will still attract and support bee pollinators. If they retain their ultraviolet nectar guides, then the bees should see them. However, I’ve seen more than one report showing little to no bee activity on the red and pink hybrids.^1,2

Anise Hyssop serves a multitude of pollinators providing nectar and pollen. Like Monarda (https://wildthingsinthe.garden/2023/07/31/the-gardens-super-station/), Fragrant Hyssop has been identified by pollination ecologists as attracting large numbers of native bees. The Xerces Society for Invertebrate Conservation also designated Fragrant Hyssop of Special Value to Bumble bees and Honeybees. Butterflies and skippers use it for a nectar source.

Pollination in Fragrant Hyssop hinges on both the individual flowers’ structure and the different bees’ anatomies. The nectar is secreted by a disc at the base of the flower. Pollen-carrying anthers are located on the top lip of each flower. When bees root for nectar, pollen rubs off onto their heads or thorax. As they move to a bloom with a receptive stigma, female part, the pollen transfers and fertilization occurs.

The many native bees that visit Hyssop range from large to tiny. Bumble bees are the largest. I’ve seen Common Eastern Bumble bee (Bombus impatiens), Brown-Belted Bumble bee, (Bombus griseocollis), Two-Spotted Bumble bee (Bombus bimaculatus), and Golden Northern Bumble Bee (Bombus fervidus) on my Fragrant Hyssop. They use both nectar and pollen for their larva.

Large Leaf-Cutter bees use Anise Hyssop’s nectar. In the process, they are efficient pollinators. In contrast to other bees, pollen accumulates on the Leaf-Cutter bees’ abdominal scopae (specialized pollen collecting hairs). It is transferred to the stigmas from there.

Digger bees (Melissodes) and smaller Leaf-Cutter bees (Megachile) are mid-sized bees. They also collect both pollen and nectar from Anise Hyssop.

The Halictid bees (Lasioglossom), small Resin bees (Heriades) and Masked bees (Hylaeus) are small bees that gather resources from Fragrant Hyssop. Dufourea monardae is included in this group. D. monardae is a specialist or oligolectic bee that visits Monarda fistulosa and Agastache foeniculum. These small bees can collect pollen from the anthers extending from the flowers. When harvesting nectar, they climb the style to reach the base of the flower. (The style is the stalk connecting the stigma and the ovary.)

Fragrant Hyssop provides an excellent late season nectar source for butterflies, skippers and moths including Silver Spotted Skipper Butterflies (Epargyreus clarus), Peck’s Skipper Butterflies (Polites peckius) and the Great Spangled Fritillary Butterfly (Speyeria cybele). They reach their proboscis into each tiny bloom to find the nectar. Hyssop also works well in Monarch Way Stations providing food after most milkweed has stopped blooming.

I hope you enjoyed this exploration of Anise Hyssop and its wonderful visitors! I’d love to hear your thought about this blog or stories about your own experiences in the garden. Please leave me comment and let me know your thoughts!

References:

Eierman, Kim,11 April 2014, “Ecobeneficial Interview: Annie White on Native Plant Cultivars, Native Plants and Pollinators”, Youtube, https://www.youtube.com/watch?v=HTmuDcEzTOw
Caldwell, Cathy, (2021, August-Vol.7, No.8) Anise hyssop, Piedmont Master Gardeners, https://piedmontmastergardeners.org/article/anise-hyssop/
Riddle, Sharla, (2016, May, 20) How Bees See And Why It Matters, Bee Culture: The Magazine of American Beekeeping, https://www.beeculture.com/bees-see-matters/