Native Plant Showcase: Agalinis tenuifolia (slender false foxglove)

By Lise Fracalossi

One of the things we’re sowing right now is Agalinis tenuifolia, a tiny-but-mighty late summer flower.

What makes this one unique is the fact that it’s hemiparasitic, meaning it’s (partially) a PLANT VAMPIRE.

Like Bunnicula. But pinker. And only a part-timer.

Photo of a small, pink and red flower, born singly, with five petals fused into a tube; it also has slender, spear-like leaves

Agalinis tenuifolia, a small pink and red-spotted flower with petals fused into a tube and slender, spear-like leaves. I found this one on a path leading between a campsite and the beach.

Photo by Lise Fracalossi, August 2021, Ausable Point Campground, Peru, NY

Species: Agalinis tenuifolia

Common name(s): Slender false foxglove, common false foxglove, slender gerardia, common gerardia

Flower Appearance: a single pink flower with five fused petals – two above forming a hood, and three below. (Interestingly, this pattern is also found in many members of the mint family Lamiaceae. Agalinis tenuifolia is not in the mint family, but it is in order Lamiales, so it’s not that distantly related). The flower has four stamens and a single pistil.

Leaf/stem appearance: Leaves are simple, slender and needle-like, arranged oppositely on a slender stem.

Fruit: A dry capsule that dehisces (splits open) when ripe.

Habitat: according to Prairie Moon Nursery, where I sourced the seed, it prefers “slightly disturbed habitats.” This seems consistent with my observations; I have observed it on or near paths, in forests and along beaches.

Native To: All states of New England, and pretty much anywhere in the U.S. and Canada east of Colorado.

Light: Sun or part shade

Moisture: Medium

Height: 8-24" (20-60cm)

Blooms: Late summer/early fall. All my observations date from late August.

iNaturalist observations:

Now that we’ve covered the basics, please enjoy some patented Lise Plant Facts™️.

  • Agalinis tenuifolia is hemiparasitic. While it can and does photosynthesize, it also uses its root-like “haustoria” to steal nourishment from nearby plants. In particular, it prefers to m0nch on graminoids, i.e. grasses, sedges, or rushes.

  • Haustoria, by the way, is a term used not only in botany but in mycology! The hyphal tips of Cordyceps – you know, the zombie fungus – are also called haustoria.

  • This year (2024), we interplanted A. tenuifolia with Schizachyrium scoparium, little bluestem, a native grass. Since it requires a longer cold moist stratification period than little bluestem, we are hoping the grass will germinate first and be able to provide some early nibbles to A. tenuifolia. Like most of our plants, this is winter sown outdoors, meaning it should get its period of cold, moist temperatures and germinate in the spring when it’s ready.

  • One of the germination codes for this on Prairie Moon Nursery is “?” It’s always interesting when the seed merchant just gives us and says “🤷‍♂️; let us know what you figure out.”

  • A. tenuifolia is in family Orobanchaceae, the broomrape family, which contains a number of different parasitic plants. Agalinis – as well as a number of other genera in Orobanchaceae – was originally in Scrophulariaceae, the figwort family, which is currently being torn apart by botanists as being “grossly polyphyletic.”

“Grossly polyphyletic” is what passes for shade, in botany.

(hahahaha shade because trees get it get it?)

  • Slender false foxglove is a host plant for the Common Buckeye butterfly, Junonia coenia, native to most of the eastern U.S.

  • “What do I do with this?” While it seems like Agalinis tenuifolia is adaptable to a wide range of soil conditions, I think of it as liking sandy, nutrient-poor soil, given where I’ve found it. Personally I plan to add it to the “rock garden” I’m building.

Photo of a small, pink and red flower, born singly, with five petals fused into a tube; it also has slender, spear-like leaves

This specimen I found in Lunenburg, along a path leading to a power line clearcut.

Photo by Lise Fracalossi, August 2019, Large Town Forest, Lunenburg, MA

In conclusion: I love this little vampiric guy, adding a splash of pink at a time of year when flowers are beginning to die back. Despite the YOLO germination code, I hope that I get a few plants out of it, if only for myself.

Sources:

Featured image: “Species from Eastern North America Common name: Slenderleaf false foxglove Photographed in Boyle Park, Little Rock, Pulaski County, Arkansas”, Eric Hunt, Wikimedia Commons