Native clover conservation in the Bluegrass: an agronomic perspective

Jonathan O.C. Kubesch, University of Tennessee

Clovers are an odd group of plants caught between agriculture and agronomy, especially in the Bluegrass. Agronomists and cattlemen find clovers important for their nitrogen contribution and nutritive value to livestock. Horse owners fear clover for the fungal pathogen behind slobbers. Wildlife managers use them for food plots. Of the roadside clovers, most came to Kentucky with settlers (Ball et al., 2015; Bryson and DeFelice, 2009). Those red and white clovers came with the tall fescue and Kentucky bluegrass. These species play an important role in Kentucky agriculture; however, the horse parks and cattle farms have replaced the natural ecosystems in the state (Noss, 2013; Campbell, 2014; Campbell, 2010).

In addition to these introduced species, Kentucky has three prominent native clovers: annual buffalo clover, running buffalo clover, and Kentucky clover (Vincent, 2001). Although collections of the native clovers have been made across Kentucky, it is really very uncommon to find these populations unless one knows where someone else has previously found it. It is unlikely that the reader will find these species in the local park or native area.

Annual buffalo clover (Trifolium reflexum), is spread throughout most of the eastern United States. The beautiful blooms have led to its potential as a horticultural species (Quesenberry et al., 2003). Of the native clovers, the genetics of the flowering in annual buffalo clover have been the most explored: red, white, and pink flowers (Quesenberry et al., 2003). At one point, it was favored over naturalized white clover in unimproved grazing lands (Killebrew, 1898).

Running buffalo clover (Trifolium stoloniferum) is a perennial species limited to the Ohio River Valley and Missouri. Plants spread on thick runners like strawberries. The species was investigated as a potential forage in the 1990s, and has been the subject of interest for herbivory dynamics in the eastern United States. The thick seed coat requires scarification in order for the seed to germinate (Kubesch, 2018; Sustar, 2017). Hoof action has been proposed as a driver in the ecology of the species, but a general disturbance regime seems necessary for the species to persist in the landscape (Kubesch, 2018). With some sandpaper and a few hours of free time, seed can be scarified. Running buffalo clover grows readily in the greenhouse.

Running buffalo clover in the greenhouse. Photo credit: Jonathan Kubesch
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Genus SCROPHULARIA in Kentucky:

Scrophularia marilandica (L.) and Scrophularia lanceolata (Pursh)

By Chris Bidwell 

Kentucky has two native species in the genus Scrophularia of the Scrophulariaceae/Figwort family: Scrophularia marilandica (L.) – Eastern/Late Figwort and Scrophularia lanceolata – Early Figwort (Pursh). S. marilandica is infrequent and primarily in Kentucky’s east-central and western counties. S. lanceolata is to be expected as it had been reported in Carroll County in 1986 but no further collections have since been reported. S. lanceolata is found in six of the seven states bordering Kentucky – it is not documented in Tennessee. Both S. marilandica and lanceolata are similar in description, habitats, and usages. Close inspection of the flower’s stamens is necessary to accurately identify which Scrophularia one is examining. S. marilandica has a purple-brown sterile stamen which is longer than wide while S. lanceolata’s sterile stamen is greenish/yellow and is wider than long. Minor differences as blooming times of June-October for S. marilandica and May-July for S. lanceolata can overlap and make identifying difficult from a distance. S. lanceolata has coarser, serrated, narrower leaves and larger seed capsules. These minor differences can be subject to interpretation which makes close examining of sterile stamens mandatory to identify the species. One reason Early Figwort (S. lanceotata) is overlooked may be due to the need to closely inspect flowers – distances/terrains may discourage one from getting to the plant to inspect accurately.

Scrophularia marilandica – Late/Eastern Figwort
Scrophularia lanceolata – Early Figwort

Both Early Figwort and Eastern Figwort are herbaceous dicot, perennials ranging from 3-8 feet tall with furrowed green stems. The stems do change to a woody texture and color in late summer and persist through winter. Opposite, petioled, and serrated leaves up to 8 inches long and 3.5 inches wide are triangular to lance shaped. Panicled irregular flower clusters are oppositely attached at end of the stems. Flowers are cylindrical/urn shaped 1/3- to 1/2-inch-long with an opening 1/3 of the flower’s length. The floral formula is K(4-5)Co(5)A(5) and 6(2). Each flower has a green calyx with 5 blunt teeth. The corolla with 5 rounded lobes with normally a dull green exterior and a predominantly brown-purple interior depicts Scrophularia marilandica while a reddish-brown exterior and yellow-green interior exist in Scrophularia lanceolata. It is important to realize however that the corolla color may vary/overlap in shades/mixes of green, yellow, red, and brown. The corolla’s 2 upper lobes that function as a hood keep rain/moisture from entering and diluting the rich nectar. The 2 lateral lobes help form the opening and the lower lobe curves downward serving as an excellent landing space for pollinating insects. Five stamens are present: 4 fertile and 1 non-fertile/sterile stamen. Scrophularia marilandica has a reddish/purple/brown infertile stamen while Scrophularia lanceolata’s stamen is yellow/green. These infertile stamen’ s color is the solid key to identifying the respective species. The infertile stamen is appressed against the upper interior posterior corolla. The 4 fertile stamens which may be fused are at the bottom of the anterior corolla. (See accompanying photos.)

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