Every year I find a new plant to become fixated with. Past notable plants include the bush clematis (Clematis fremontii) hairy beardtongue (Penstemon hirsutus), and camas (Camassia quamash). Our garden is dotted with these beauties, and I tend to plant them in abundance. This past summer two new plants made my… “I must have these, or my life will not go on” list. Creeping Jacob’s Ladder (Polemonium reptans) and goat’s rue (Tephrosia virginiana).
I’ve also had plants on my list such as the wild petunia (Ruellia humilis) and that quickly went from “I must have” to “I must destroy.” If you’ve grown wild petunia, you soon find out in two seasons how bountiful the plant can become and then it starts to pop up everywhere. Everywhere. Lesson was learned. As a side note, wild petunia is a great perennial that might be better suited for larger prairie urban to rural gardens where it can meander without care.
Back to my two new beauties. Creeping Jacob’s ladder is a spring blooming perennial that does well in shaded to partial sunny areas in the garden. There is no consistent literature on the height and width of the plant. From my own experience it grows about 18” tall and same spread. It is known to spread by rhizomes and seed making an excellent ground cover. Flowers are described as a periwinkle blue with a lighter color eye. I worry about it becoming another wild petunia and taking over large swaths of the garden. However, from several resources such as Iowa State University it is not a competitive plant and can be kept in check by interplanting other perennials (McMullen, 2024)[i]. According to Heather Holm the plant is visited by various insects such as syrphid flies, beetles, and several kinds of bees including mason bees, mining bees, digger bees and the bumble bee[ii]. It is also worth noting several other authors mention that the plant can go dormant during the summer in drought conditions.
Goat’s rue is the other perennial that has caught my attention. It does well in more sun than shade and should bloom most of the summer. This member of the bean family has a torrid history in both agriculture and nomenclature. When seeking out the currently accepted scientific name I only found a long string of synonyms and yielded to the Missouri Botanical Garden Plant Finder: Tephrosia virginiana. Goat’s rue bicolor flower resembles sweet peas with white upper petals and pink lower petals. This plant was once used to help increase the production of milk in goats. However, the plant also produces a natural toxin, rotenone, that has been used as an organic insecticide[iii]. Growing about 18” tall, about half as wide, this perennial is best left undisturbed once planted as it does not transplant well. As for plant/insect interactions the literature is scarce, and I’ve not come across any references sharing what and who might visit the blooms. As a member of the bean family, it can help fix nitrogen in the soil.
When looking for Goat’s rue make sure you are diligent with knowing your plant names. There is a Federal noxious weed, Goatsrue (Galega officinalis), that should not be planted in any landscape setting. It can form dense colonies that compete with the native plants along with being toxic to sheep. According to Nebraska Invasives it is found only in a few counties in the state[iv]
I’m excited to see how these new introductions will fair in the urban garden. I am also hoping that they make good neighbors.
[i] https://understory.nrem.iastate.edu/polemonium-reptans
[ii] Pollinators of Native Plants: Heather Holm
[iii] https://plants.ces.ncsu.edu/plants/tephrosia-virginiana/
[iv] https://neinvasives.com/species/plants/goatsrue
