A Report of Two Species of Bothriochloa (Poaceae) New to South Dakota

Home , Bothriochloa, Bothriochloa ischaemum, Bothriochloa laguroides

Proceedings of the South Dakota Academy of Science, Vol. 97 (2018) 77

A REPORT OF TWO SPECIES OF BOTHRIOCHLOA (POACEAE) NEW TO SOUTH DAKOTA

Jordan Purintun1 and Mark Gabel2* 1South Dakota Game, Fish and Parks 523 East Capitol Ave. Pierre, SD 57501 2Black Hills State University 1200 University Spearfish, SD 57799-9008 *Corresponding author: [email protected]

ABSTRACT

Bothriochloa Kuntze is a genus of grasses usually found in tropical to warm temperature regions. We report the occurrence of two species of the genus as new to South Dakota. Bothriochloa ischaemum (L.) Keng is native to Eurasia and was introduced to the southwestern United States as a means of erosion control and for dry land forage. It was discovered along 5-km of Highway 37 north of Mitchell (Davison County) in September 2017. Bothriochloa laguroides (DC.) Herter is described as both native and introduced to the United States. It is nor- mally found in the southern United States and Mexico. In South Dakota it was collected in Spearfish (Lawrence County) in 2015 and 2016.

Keywords

Bothriochloa, new species, grasses, Poaceae, flora, South Dakota

INTRODUCTION

The genusBothriochloa Kuntze includes approximately 35 species of C4 grasses distributed principally in the tropical and warm-temperate regions of the Eastern Hemisphere, with nine species native to the United States (Allred 2003). The species native to the Eastern Hemisphere, along with the genera Capillipedium Stapf and Dichanthium Willemet, comprise the bulk of the ‘old world bluestems,’ a group of 64 to 69 species that has been the object of extensive range and forage research in the Southern Great Plains (Coleman et al. 2004). Deliberate intro- ductions of Eurasian species to the United States for range improvement date to 1914, when yellow bluestem (Bothriochloa ischaemum (L.) Keng) was introduced to California from Amoy, China (Celarier and Harlan 1955). Extensive research and breeding experiments have taken place in the south-central Great Plains since the mid-1900s (e.g. Celarier and Harlan 1955; Harlan et al. 1958, 1961a, 1961b, 1962, 1963), and Bothriochloa species are now widely cultivated in that region (Coleman et al. 2004). Since the early 2000s, a growing body of research 78 Proceedings of the South Dakota Academy of Science, Vol. 97 (2018) has been published on the invasive qualities of some species, in particular yellow bluestem (e.g. Sammon and Wilkins 2005; Gabbard and Fowler 2007; Hickman et al. 2006). Synonyms for the taxa of Bothriochloa are legion. The Integrated Taxonomic Information System (ITIS 2018) lists 14 synonyms in 7 different genera for B. laguroides and 10 synonyms in 6 genera for B. ischaemum. Here we report the first documented occurrences of twoBothriochloa species in South Dakota, including Bothriochloa laguroides (DC.) Herter in Fall River and Lawrence Counties and Bothriochloa ischaemum (L.) Keng in Davison County.

RESULTS

Bothriochloa laguroides (DC.) Herter var. torreyana (Steud.) M. Marchi & Longhi-Wagner (silver bluestem) is found primarily in the southern United States and in northern Mexico (Vega 2000, Allred 2003). Bothriochloa laguroides was collected (Gabel 7091) in Spearfish, Lawrence County, SD, at 44.40577º N, 103.85970º W at an elevation of 1105 m (3625 ft) on October 27, 2015. The plants were growing in a lawn area after mowing had ceased for the year. The plants were observed again at the same location in 2016, but were not present in 2017. Specimens are deposited at BHSC and SDC (acronyms as per Thiers, continuously updated). In the course of this study we learned that Bothriochloa laguroides had been collected in the southern Black Hills in 2000 by Butterfield (s.n.) in Fall River County, but the collection was unreported until now. That collection was observed for this study and is housed at Chadron State College Herbarium (CSCN). Four specimens of Bothriochloa ischaemum (L.) Keng var. ischaemum were collected just north of Mitchell, Davison County, SD, on September 25, 2017. Plants were observed in the median and roadsides of the four-lane South Dakota Highway 37 over approximately 5 km between 43.82300° N, 98.02889° W and 43.78340° N, 98.02823° W. The collected specimens are in preparation at the C. A. Taylor Herbarium at South Dakota State University and will be deposited at SDC and BHSC. The population was first recognized by Jeff Hansen of Topeka, KA, on September 24, 2017, and was reported to the senior author on the same day. Specimens were identified to the species level using Allred (2003). Identification to varietyischaemum , as opposed to variety songarica, was based primarily on information in Celarier and Harlan (1955). Dr. Timothy Springer, a research agronomist at the USDA-ARS Southern Plains Range Research Station in Woodward, OK, suggested the darkened nodes of the observed plants may indicate our population is attributable to the cultivar ‘Ganada’. On September 25, 2017, roads intersecting the affected area were searched for approximately 3 km east and west of Highway 37, as were 20-km lengths of Highway 37 immediately north and south of the affected area. No additional populations were observed, suggesting the species was limited to the documented area. Personnel from the South Dakota Highway Department spot-sprayed glyphosphate herbicide on the plants on October 17 and 18 of 2017. Road con- struction began on the affected area in the summer of 2018. Proceedings of the South Dakota Academy of Science, Vol. 97 (2018) 79

DISCUSSION

Both Bothriochloa ischaemum and B. laguroides are known to spread into roadsides and waste ground. The former has been reported in southeastern Nebraska (Kaul et al. 2006). It is said to be a “…pernicious weed that is replacing native prairie species” (Stubbendieck et al. 2017). B. laguroides has been reported to be in southern Nebraska (Kaul et al. 2006), and introduced plants are reported to survive near Lovell and Gurnsey, Wyoming (Skinner 2010). The Northern Great Plains portal of SEINet (2018) was searched for occurrences of Bothriochloa ischaemum and B. laguroides. The former was reported from 19 southern states, 1 territory (Puerto Rico) and Mexico. Of the 1125 records available for B. ischaemum, 53 specimens were collected in the period from 1950-1967. During the years 2000-2017, 371 specimens of that species were collected. B. laguroides was represented by 1487 records from 15 southern states and Mexico. In the period from 1950-1967, 76 records are present. In the years 2000-2017, 294 records are available. The Northern Great Plains is an area currently undergoing climate change. The increase in annual temperatures in North Dakota over the past 130 years is the greatest of the 48 contiguous states (National Climate Assessment 2014, United States Environmental Protection Agency 2017). Days with maximum temperatures over 100 ºF (~38 ºC) are projected to double by mid-century (National Climate Assessment 2014). Minimum night temperatures of over 60 ºF (~16 ºC) are projected to follow the same pattern (United States Environmental Protection Agency 2017). In addition to warmer daytime and nighttime temperatures, precipitation will increase. Precipitation models vary in the amount of change for the remainder of the century, but the trend predicted for South Dakota is an increased amount of precipitation, especially heavy precipitation events (National Climate Change Assessment 2014, Wing et al. 2018). Climate change has stimulated changes of flowering time, shifts in species dis- tribution, declines of native species and increases of invasive species. Species dis- tributions in the Great Plains have moved to higher latitudes at a rate of 16.9 km per decade with projections for greater changes in the future (National Climate Assessment 2014). We are not surprised that Bothriochloa species have been discovered in South Dakota. With increased temperatures and increased precipitation in South Dakota it is very likely that more range extensions of plant species will be discovered in the future.

ACKNOWLEDGEMENTS

We wish to thank A. Boe and G. Larson for reviewing and improving the manuscript. We also extend thanks to the curator of CSCN for the loan of the specimen. 80 Proceedings of the South Dakota Academy of Science, Vol. 97 (2018)

LITERATURE CITED

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