Some Rarities and Weedities

Blue Jay Barrens has never had an abundance of early spring wildflowers, and as the deer population increases, those that were here years ago have decreased in number. As a result, my perception of the early spring blooming season is that of a sprinkling of small white blooms. All come from tiny members of the mustard family. Some are quite rare, while others are prolific weeds. The first to show itself is generally Michaux’s Leavenworthia, Leavenworthia uniflora, a species that is listed as threatened in Ohio. I’ve been told that I feature this species, along with a couple of other similar subjects, far too often in this blog. Fortunately, the person providing that information is quite mistaken, so I will continue to discuss these plants at whatever times I deem appropriate.

The Leavenworthia is an annual plant and races along in its attempt to provide seeds for future generations. The blooms, held only a couple of inches above the soil surface, are hard enough to see. Add to that the rapidity with which the bloom withers around a quickly growing seed pod, and a person is lucky to catch a glimpse of these flowers at all.

The smallest of the early bloomers barely reaches an inch in height from the ground up to the top of the flower stalk. This is Carolina Whitlow-grass, Draba reptans, another state threatened species. Carolina Whitlow-grass is not a species that you will casually observe while out walking on an early spring day. You have to get down close to the ground and actively seek out these plants.  One identifying characteristic of this plant is the relatively smooth stalk supporting the cluster of flowers.

Prior to flowering, it’s best to have some type of magnification when trying to view the plant. At this stage, the plant always reminds me of a tiny cactus, but there’s no fear of being stuck by spines here.

Wedge-leaved Whitlow-grass, Draba cuneifolia, is the third early spring rarity that I regularly see. The leaves of this species have shallow pointed lobes along the margins, but this leaf feature may not be noticeable in very small plants.  The surest way to separate Wedge-leaved Whitlow-grass from the preceding the species is by comparing the flower stalks. The flower stock here is densely hairy.

Wedge-leaved Whitlow-grass has the typical four petaled flower of the mustard family. Each petal has a shallow indentation at the tip.

Several non-native species add their bits of whiteness to the spring blooming season. These are weedy species that are commonly found in most lawns and gardens. Whitlow Grass, Draba verna, although related to our native rarities, is an extremely common non-native weedy plant. One reason that these plants are so successful in human disturbed habitats is the fact that they flower and distribute their seed before most people become active with their gardening and weeding activities. The seed from these plants sits quietly in the soil through the summer and fall months, and is ready to spring forth the following winter.

The four petals of the Whitlow Grass are so deeply split down the center that they are often mistaken as having eight petals. This feature quickly distinguishes these alien plants from our native species.

Becoming ever more common in the urban landscape is the Hairy Bittercress, Cardamine hirsuta.  Blooms of this plant quickly disappear in favor of elongated pods that rapidly fill with ripe seed.  Once the seed is mature, the pods will violently open at the slightest touch and scatter seeds in a wide area around the plant.  The seeds are easily carried away on people’s shoes and gardening tools, to colonize fresh areas.

Field Pennycress, Thlaspi arvense, is a non-native quick to invade into bare or disturbed ground. In most situations it forms thick patches of plants.

The Field Pennycress seedpods seem to develop as quickly as the flowers can form. In just a few days a tall spike of developing seedpods replaces the initial flower cluster. These non-native species are interesting, but my goal is to manage for native populations and that generally means that the non-natives are considered weeds and must go.

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.