Leavenworthia Compared to Hairy Bittercress

I’ve recently received emails from two different people, describing their exciting discoveries of populations of the state threatened Leavenworthia uniflora in their lawns and flowerbeds. It’s always exciting to find a population of rare plants, especially when they’re growing as thick as weeds, which is how one correspondent described his find. They had both read some of my earlier posts on the species and wanted me to share in their joy of their newfound flora neighbors.

Unfortunately, the photo documentation they sent along with their emails showed the plants to be something other than Leavenworthia.  Their plants did bear a superficial resemblance to the Leavenworthia, but they were actually a non-native weedy species known as Hairy Bittercress, Cardamine hirsuta. No wonder they were thick as weeds.  I thought it appropriate to make a comparison between the two plants using easy to see features. I certainly don’t want people to be protecting weeds because of a mistaken identification, nor would I want a rare plant to be destroyed because of the same mistake.

Leavenworthia will grow in most locations that provide competition free conditions. In natural situations these are generally dry, rocky, shallow soils. These are annual plants that begin growth in early winter and by early spring, begin to flower. Leavenworthia produces leaves from a basal whorl. The leaves fan out horizontally, almost hugging the ground and presenting an appearance of level flatness across the top of the plant.

Hairy Bittercress has a growth habit similar to that of Leavenworthia, but is more typically found in areas of urban disturbance such as is found in people’s yards. It also begins growth in early winter, but it tends to flower one or two weeks earlier than Leavenworthia. The plant begins by producing several rings of basal leaves, but as it grows, the center portion of the whorl heaves upward, making the plant appear slightly mounded.

Leavenworthia flowers emerge from ground level at the center of the leaf whorl.  Flower stalks produce no leaves and bear only a single bloom at the top of the stalk.

Hairy Bittercress produces a branched stalk from the center of the whorl that produces both leaves and clusters of flowers.

Hairy Bittercress, shown on the left, produces compound leaves with leaflets that produce rounded lobes. The Leavenworthia develops sharply pointed lobes.

Here we have Leavenworthia on the left and Hairy Bittercress on the right. Hairy Bittercress most resembles Leavenworthia in its younger stages. I have yet to see both of these species actually growing together in a single location. To get this photo, I plucked a Hairy Bittercress rosette from another location and posed it beside the Leavenworthia. It’s easy enough now when making plant identifications to go online and find authoritative information about the plant in question. When doing that type of search, just make sure you go beyond the photo and read what the text has to say about the plant.

Prairie Garden Spring Maintenance

The dead growth in the Prairie Garden is removed each spring.  I used to do an occasional spring burn, but abandoned that management technique because of the potential threat to the overwintering pupae of the state endangered Unexpected Tiger Moth, Cycnia inopinatus.  Now I mow and lightly rake, which greatly reduces the threat to the pupae tucked away in the leaf litter at the base of their larval food plant, Butterflyweed.

Red flags act as warnings to use caution with the mower in certain areas.  I’ve learned not to trust myself to remember every little obstacle hidden in the tall grass.

The plants would grow even if I allowed this dead material to remain.  The reason for removing the top growth is to facilitate observation of the various growth stages of each species.  Getting to know the plants at different times of the year was my primary motivation for creating this garden.

Even though the grass looks impenetrable when viewed from a distance, it actually has many openings that allow sunlight down to low growing plants.

It only takes a few passes with the brush mower to get things cut down.

What’s left looks pretty brown.

A closer look reveals a lot of color being displayed by early season growth.

Western Sunflower, Helianthus occidentalis, begins growth early in the season.  Even though Western Sunflower will grow to a height of six feet or more, most of the leaves remain at ground level, so the plant must make full use of early season sunlight before it becomes shaded by neighboring plants.

This is Hairy Bittercress, a weedy non-native that I first found here about 20 years ago.  It is now everywhere around the yard.

Hairy Bittercress thrives in bare, disturbed earth.  Large ant mounds provide an ideal growing environment.  All of my yard mounds harbor this weed and the plant is beginning to show up on ant mounds in the fields.

Fortunately, most of the greenery in the prairie garden is due to growth of native species.  These are the basal leaves of Gray-headed Coneflower, Ratibida pinnata.

Wild Bergamot, Monarda fistulosa, is coming along nicely.  A morning low of 11 degrees doesn’t seem to have done any damage to the leaves.

The population of Round-podded St. Johnswort, Hypericum sphaerocarpum, keeps shifting its position around the garden.  Clumps of plants live for two or three years and then die.  There are always new plants coming up somewhere else to take their place.

Prairie Dock has hardly made it out of the ground, but something has already nipped off the first leaf.  Deer browse heavily on this plant in the early spring, but ignore it later on.  I imagine that more suitable forage becomes available as the season progresses.

I suspect this to be the work of an Eastern Cottontail.  There seems to be a rabbit’s nest in the garden every year.  Usually she digs up some plant that I’m particularly sorry to lose.

Prairie Garden - New Part - Early April

The most recent portion of the Prairie Garden is too new to offer much of interest.  This area was sprayed twice with glyphosate herbicide last October and was seeded in November and December.  I always try to plant seed at the same time of year that it is naturally being dropped by the plant.  I figure that should give the seed the right combination of cold, heat, wet or dry conditions necessary for germination.  It’s more successful and much easier than packaging seed and storing it for periods in the freezer.

The glyphosate spray got rid of many of the late season grasses and forbs, but left plenty of seeds from those early flowering species.  The bulk of the green plants now showing are non-native species typically found in disturbed areas around the house and yard.  This is Corn Speedwell, a low growing plant that has no fear of lawn mowers.

The only plants of any height are the Hairy Bittercress.  These little weeds forcibly propel the ripe seeds from the pod, so you don’t want to make a close examination without some eye protection.

Whitlow Grass, Draba verna, has petals that are split down the middle, so the regular four petals often appear to be eight. The split petal easily distinguishes this non-native species from the native Drabas.

Many years ago I excitedly thought these narrow leaved seedlings to be those of a Blazing Star.  I was really disappointed when they turned out to be English Plantain.

Mouse-ear Chickweed is a rather interesting looking plant, but it’s also one of those weedy non-natives.

Purple Dead Nettle often forms a solid mass in crop fields and other disturbed ground.  Fortunately, I don’t have to deal with that type of infestation.  Many of these non-native plants will persist indefinitely in the Prairie Garden, but their vigor will be reduced by competition with the prairie natives.

Many of the native seedlings won’t become evident until later in the season.  There are a few that show themselves early in the spring and they give me hope that my seeding will be successful.  Gray-headed Coneflower is a rapid grower that can often flower in its first year.

Several Purple Coneflower seedlings are appearing.  Besides being a great attractor of butterflies, the Purple Coneflowers help convince the more confused individuals that this is an actual garden and not a weed patch.

Wild Petunias are one of the few natives that readily volunteer in the yard.  It’s nice to know that the lawn hasn’t been completely taken over by alien species.