Biology:Bothriochloa ischaemum

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Short description: Species of grasses

Bothriochloa ischaemum
Scientific classification edit
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Clade: Commelinids
Order: Poales
Family: Poaceae
Subfamily: Panicoideae
Genus: Bothriochloa
Species:
B. ischaemum
Binomial name
Bothriochloa ischaemum
(L.) Keng
Varieties
  • B. i. var. ischaemum
  • B. i. var. songarica (Rupr. ex Fisch. & C.A.Mey.) Celarier & J.R.Harlan
Synonyms[1]

Bothriochloa ischaemum is a species of perennial grass in the family Poaceae, found throughout much of the world. It is commonly known as yellow bluestem. Two varieties are recognized, of which Bothriochloa ischaemum var. ischaemum is native to Europe, Asia, and Africa and naturalized elsewhere,[2] and var. songarica is native to Asia and naturalized elsewhere.[3] Var. songarica is an invasive weed in Texas, where it is known as "King Ranch bluestem"; it has displaced native grasses in large areas of central and south Texas.[4] The species name come from the Ancient Greek ischaemum, a styptic (causing ischemia).

This bunchgrass is characterized by tufts and culms that grow 14-48" tall and have an extensive root system. Near the collar are thick leaves (1-10") that are smooth, flat, and yellow-green in color.  Leaves are adorned with long, silky hairs. The plant has flowering stems which spread densely underground and flower up to 4 feet long[5]. The stems present brown to purple at the nodes and have green rounded leaf sheaths that turn yellow and straw-like when matured. The inflorescence is red-purple colored with spikelets[6].  Invasive to many parts of North America, B. ischaemum negatively impacts the habitats and biodiversity in areas of introduction.

Although categorized as an invasive grass species, B. ischaemum is native to temperate and subtropical regions of Eurasia[7]. This includes parts of the Asia-Pacific shores and Atlantic coasts of Europe[6]. B. ischaemum was originally introduced into Texas for farming purposes in the early 1900s. Specifically, it was intended for use in forage production, rangeland improvement, and erosion control[5]. The species was favored for its ability to tolerate environmental stress and quickly establish in disturbed areas to aid in erosion mitigation and restoration[8]. These traits have led to a wide distribution across South and Central Texas, while these areas experienced periods of drought[9]. Mode of distribution for B.ischaemum include seed production and vegetative growth through underground stems. This allows for rapid expansion and formation of dense strands in invaded habitats[5].

Similarly, habitat alterations, especially due to human land usage, have promoted the successful invasion of B. ischaemum. Highly functional habitats with high biodiversity are more resilient to invasive species. Thus, habitats with significant alteration to the soil and biodiversity are more susceptible to nonnative species thriving and outcompeting native species[10]. Land use for agricultural or urbanization purposes decreases the amount of grassland cover, altering the habitat and soil conditions that favor invasion[10]. Habitat degradation paired with persistent droughts of sandy grasslands allows B. ischaemum to quickly invade using its C4 photosynthetic mechanism to quickly reproduce and remain resilient by its morphological plasticity[10].

Ecological impact

A rapidly spreading and aggressive grass, B. ischaemum quickly outcompetes the native species present[5]. Once established in an area, B. ischaemum forms dense monocultures, leaving no space for native plants to grow. The plant grows an extensive root system and dense sod, further enhancing its competitive advantage against native species. Furthermore, B. ischaemum reduces available soil nitrogen and releases chemicals into the surrounding soil, inhibiting the growth of native plants, reinforcing its dominance[5][11].

The displacement of native species due to outcompetition by invasive B. ischaemum resulting in a decline of biodiversity has a greater impact on the food web of each habitat[12]. Studies have found that B. ischaemum dominated areas feature lower insect abundance and diversity[12]. This leads to declines in grassland bird populations, specifically species abundance and richness, as they rely on insects as their primary food source[12]. As bird populations decline, the ecosystem is disrupted further as limited diversity extends within rodent communities[6]. Additionally, B.ischaemum acts as a host for the red-streaked leafhopper, a pest species. This insect is known to transmit a harmful phytoplasma and has been linked to significant agricultural losses, specifically to sugarcane in Thailand[6].

On the other hand, B. ischaemum provides value in agriculture practices and land management. With the ability for rapid germination and population establishment, B. ischaemum has been noted to benefit hay production and stabilization of disturbed soils. Additionally, it is capable of thriving in harsh conditions through its drought, grazing, and fire tolerance. However, while these traits can be beneficial to an extent, they also contribute to the invasiveness of the plant. Its rapid establishment and growth allow it to outcompete native plants, reducing biodiversity and negatively impacting ecosystem dynamics.[13]

Another benefit of B. ischaemum, which prompted the initial introduction of this plant to North America, is its ability to be highly resistant to droughts[9].  This is due to the deep and extensive root systems that the plant builds underneath the surface. The roots grow 2-3m deep in clay soil, resulting in two times as much as the vegetation growth above the surface[9]. This depth allows the plants to tap into other water sources during periods of drought, enhancing the overall survival and fitness of this species. Furthermore, when studied under varying levels of drought stress, this plant was found to reach its best water use efficiency under mild drought stress as it limits the transpiration rate and focuses on increasing the root system for better water absorption[14].

The benefits of B. ischaemum in relation to its high tolerance regulates its use in native populations. Used to combat drought stress and soil erosion, as well as promote agricultural growth and provide forage for cattle[11].  Overall, these benefits that B. ischaemum provides have prompted its introduction into other areas of the world.

Control methods

Current eradication methods combine the use of mowing, burning, and herbicides to suppress B. ischaemum populations. However, for large-scale invasions, these methods have proven insufficient. Research has found integrated management strategies to be the most effective in controlling B. ischaemum populations[6]. Prescribed burning has been found to reduce population levels significantly, especially when combined with mowing and herbicide treatments. As B. ischaemum produces seeds in late-summer and fall, timely mowing is required to prevent seed maturation. Once seeds have matured, mowing is no longer an effective control strategy. Furthermore, competition strategies have been found to be effective. Specifically, over-seeding with other plant species can limit resources that contribute to B. ischaemum growth, ultimately suppressing the invasive plant[15].

It is important to note that control strategies are significantly effective only when done together. Herbicide use alone or mowing alone are not sufficient to prevent further spread of B. ischaemum. Therefore, to properly control the spread of this plant, long-term, repeated management is required[15].

References

  1. ↑ "The Plant List: A Working List of All Plant Species". http://www.theplantlist.org/tpl/record/kew-399335. 
  2. ↑ {{citation | mode = cs1 | title = Bothriochloa ischaemum var. ischaemum | work = Germplasm Resources Information Network (GRIN) | url = https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?300076 | publisher = [[Organization:Agricultural Research ServAgricultural Research Service (ARS), United States Department of Agriculture (USDA) | access-date = 16 January 2018 }}
  3. ↑ {{citation | mode = cs1 | title = Bothriochloa ischaemum var. songarica | work = Germplasm Resources Information Network (GRIN) | url = https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?310207 | publisher = [[Organization:Agricultural Research ServAgricultural Research Service (ARS), United States Department of Agriculture (USDA) | access-date = 16 January 2018 }}
  4. ↑ Gabbard, B. L.; Fowler, N. L. (2006). "Wide Ecological Amplitude of a Diversity-Reducing Invasive Grass". Biological Invasions 9 (2): 149. doi:10.1007/s10530-006-9012-x. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 "Yellow bluestem grass | AZ Invasive Plants" (in en). https://azinvasiveplants.arizona.edu/invasive-plant/yellow-bluestem-grass. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 "details". https://tsusinvasives.org/home/database/bothriochloa-ischaemum-var-songarica. 
  7. ↑ Cortez, Raquel (1955-01-01). "Studies on Old World bluestems". Tech. Bull., T-58 Oklahoma Agric. Exp. …. https://www.academia.edu/86827143. 
  8. ↑ Gabbard, Bethany L.; Fowler, Norma L. (2007-03-01). "Wide Ecological Amplitude of a Diversity-Reducing Invasive Grass" (in en). Biological Invasions 9 (2): 149–160. doi:10.1007/s10530-006-9012-x. ISSN 1573-1464. Bibcode: 2007BiInv...9..149G. 
  9. ↑ 9.0 9.1 9.2 Wied, Justin P.; Perotto-Baldivieso, Humberto L.; Conkey, April A. T.; Brennan, Leonard A.; Mata, José M. (June 2020). "Invasive grasses in South Texas rangelands: historical perspectives and future directions" (in en). Invasive Plant Science and Management 13 (2): 41–58. doi:10.1017/inp.2020.11. ISSN 1939-7291. Bibcode: 2020IPSM...13...41W. https://www.cambridge.org/core/product/identifier/S1939729120000115/type/journal_article. 
  10. ↑ 10.0 10.1 10.2 Szentes, Szilárd; Penksza, Károly; Saláta-Falusi, Eszter; Sipos, László; Kozma-Bognár, Veronika; Hoffmann, Richárd; Wagenhoffer, Zsombor (2025-05-20). "Effects of Bothriochloa ischaemum on the Diversity of Pannonian Sandy Grasslands" (in en). Land 14 (5): 1107. doi:10.3390/land14051107. ISSN 2073-445X. Bibcode: 2025Land...14.1107S. 
  11. ↑ 11.0 11.1 Kouri, Joshua D.; Rust, Emma; Souza, Lara (March 2026). "Intra- and Inter-Specific Ecological Impacts Vary Across a Gradient of Abundance of an Invasive Species, Bothriochloa ischaemum, in a Mixed-Grass Prairie". Ecology and Evolution 16 (3). doi:10.1002/ece3.73212. ISSN 2045-7758. PMID 41815290. Bibcode: 2026EcoEv..1673212K. 
  12. ↑ 12.0 12.1 12.2 Hickman, Karen R.; Farley, Greg H.; Channell, Rob; Steier, Jan E. (2006). "Effects of Old World Bluestem (Bothriochloa ischaemum) on Food Availability and Avian Community Composition within the Mixed-Grass Prairie". The Southwestern Naturalist 51 (4): 524–530. doi:10.1894/0038-4909(2006)51[524:EOOWBB2.0.CO;2]. ISSN 0038-4909. 
  13. ↑ Hickman, Karen; Harmoney, Keith; White, Allen. "Field Guide for Managing Yellow and Caucasian (Old World) Bluestems in the Southwest". https://www.fs.usda.gov/sites/nfs/files/legacy-media/r03/Yellow%20and%20Caucasian%20Bluestems%20Field%20Guide%202018.pdf. 
  14. ↑ Liu, Ying; Li, Peng; Xu, Guo Ce; Xiao, Lie; Ren, Zong Ping; Li, Zhan Bin (2017-02-24). "Growth, Morphological, and Physiological Responses to Drought Stress in Bothriochloa ischaemum". Frontiers in Plant Science 8: 230. doi:10.3389/fpls.2017.00230. ISSN 1664-462X. PMID 28286507. Bibcode: 2017FrPS....8..230L. 
  15. ↑ 15.0 15.1 Humphries, Talia; Lortie, Christopher J.; Lucero, Jacob (2025-12-01). "A systematic review and meta-analysis of Old-World bluestem control in the United States". Rangelands 47 (6): 291–302. doi:10.1016/j.rala.2025.10.002. ISSN 0190-0528. Bibcode: 2025Range..47..291H. https://www.sciencedirect.com/science/article/pii/S0190052825000665. 

Wikidata ☰ Q3847968 entry



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