Bothriochloa ischaemum
(yellow bluestem)

Preferred Scientific Name

• Bothriochloa ischaemum (L.) Keng

Preferred Common Name

• yellow bluestem

Other Scientific Names

• Amphilophis ischaemum (L.) Nash
• Andropogon ischaemum L.
• Andropogon ischaemum f. songaricus (Rupr. ex Fisch. & C.A.Mey.) Kitag.
• Andropogon ischaemum var. ischaemum
• Andropogon ischaemum var. laevifolius Hack.
• Andropogon ischaemum var. songaricus Rupr. ex Schrenk
• Andropogon panormitanus Parl.
• Andropogon patulus Moench
• Andropogon pertusus var. panormitanus (Parl.) Hack.
• Andropogon taiwanensis Ohwi
• Andropogon undulatus Pers.
• Bothriochloa insculpta subsp. panormitana (Parl.) Giardina & Raimondo
• Bothriochloa ischaemum f. ischaemum
• Bothriochloa ischaemum f. songarica (Rupr.) Kitag.
• Bothriochloa ischaemum var. ischaemum
• Bothriochloa ischaemum var. songarica (Rupr.) Celarier & J.R.Harlan
• Bothriochloa panormitana (Parl.) Pilg.
• Dichanthium ischaemum (L.) Roberty
• Ischaemum dactyloideum Montandon
• Sorghum ischaemum (L.) Kuntze

International Common Names

• English: king ranch bluestem (B. ischaemum var. songarica); Texas yellow beard grass (B. ischaemum var. songarica); Turkestan bluestem (B. ischaemum var. ischaemum); yellow bluestem (B. ischaemum var. ischaemum)
• Chinese: bai yang cao

Local Common Names

• Brazil: capim-cola-de-zorro-amarelo

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Monocotyledonae
•                     Order: Cyperales
•                         Family: Poaceae
•                             Genus: Bothriochloa
•                                 Species: Bothriochloa ischaemum

Grasses in the Bothriochloa genus are closely related to grasses in the Andropogon genus (bluestem grasses) and Erianthus genus (plume grasses). B. ischaemum was once classified as Andropogon ischaemum (Hilty, 2014).

A number of different cultivars of B. ischaemum have been widely released into the USA, full details of which can be found in Cook et al. (2005). In addition to this, two varieties exist; B. ischaemum var. ischaemum and B. ischaemum var. songarica. A number of common names relate specifically to a particular variety.

Plants typically cespitose, occasionally stoloniferous or rhizomatous, especially when heavily grazed or under frequently mowed. Culms 20-80 cm long, stiffly erect; nodes glabrous or short hirsute. Leaves basal; ligules 0.5-1.5 mm; blades 5-25 cm long, 2.0-4.5 mm wide, flat to folded, glabrous or with long, scattered hairs at the base of the blade. Panicles 5-10 cm, fan-shaped, silvery reddish-purple; rachises 0.5-2 cm, typically with 2-8 branches; branches 3-9 cm, erect to somewhat spreading from the axillary pulvini, usually with only one rame; rame internodes with a central groove narrower than the margins, margins ciliate, with 1-3 mm hairs. Sessile spikelets 3.0-4.5 mm, narrowly ovate; lower glumes hirsute below with about 1 mm hairs, lacking a dorsal pit; awns 9-17 mm, twisted, geniculate; anthers 1-2 mm (Vega, 2000).

The culm node of the variety B. ischaemum var. songarica is ringed with short hairs (Harms, 2015).

B. ischaemum was introduced into the North American Great Plains in the 1920s for soil erosion control and forage production on marginal rangelands (Celarier and Harlan, 1955). Today, B. ischaemum has been planted onto millions of hectares of marginal rangeland, roadsides and Conservation Reserve Program lands (Harmoney et al., 2004).

The two varieties of B. ischaemum have clearly differentiated introduced ranges in the USA (USDA-NRCS, 2015), with B. ischaemum var. ischaemum limited to two states and B. ischaemum var. songarica much more widespread.

Soil drainage

• free

Soil reaction

• acid
• alkaline
• neutral

Soil texture

• heavy
• light
• medium

Natural Dispersal

Natural dispersal of B. ischaemum typically occurs via the translocation of seeds by winds and water movement (Hilty, 2014).

Accidental Introduction

Seeds can be accidentally transported on vehicles, clothing, including footwear and in contaminated seed of forage grass (Hilty, 2014).

Intentional Introduction

B. ischaemum is primarily spread by humans as it is intentionally introduced into new areas as a possible source of forage for cattle and for soil stabilization as a component of roadside vegetation.

B. ischaemum is regarded as an invasive and weedy species in many areas of North America, and control is often difficult to achieve and can be costly (Mittelhauser et al., 2011; Ruffner and Barnes, 2012).

Impact on Habitats

B. ischaemum can form dense monocultures which may outcompete native plant species and decrease habitats occupied by native wildlife (Afflerbach, 2013). This reduction can potentially threaten endangered species and cause a loss to native species (George et al., 2013; Greer, 2013). An alteration of beneficial soil microbes has been reported as a result from invasion of B. ischaemum, including alterations to mycorrhizal associations (Wilson et al., 2012; Endresz et al., 2013). Potential allelopathic effects from B. ischaemum may facilitate its invasion and complicate restoration of native plant species (Greer et al., 2014).

Impact on Biodiversity

Several studies have been conducted to assess impacts of B. ischaemum on native biodiversity (McIntyre et al., 2003; Hickman et al., 2006; George et al., 2013; Greer, 2013). A study comparing native prairies with monocultures of B. ischaemum found grasshopper sparrows (Ammodramus savannarum) to become more abundant but savannah sparrows (Passerculus sandwichensis), cassin's sparrows (Peucaea cassinii) and horned larks (Eremophila alpestris) to become less abundant (George et al., 2013). In Texas, B. ischaemum is found to be displacing native grass species (Gabbard and Fowler, 2007).

• Proved invasive outside its native range
• Has a broad native range
• Highly adaptable to different environments
• Is a habitat generalist
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Benefits from human association (i.e. it is a human commensal)
• Fast growing
• Has high reproductive potential
• Has propagules that can remain viable for more than one year
• Reproduces asexually
• Has high genetic variability

• Altered trophic level
• Conflict
• Damaged ecosystem services
• Ecosystem change/ habitat alteration
• Modification of nutrient regime
• Modification of successional patterns
• Monoculture formation
• Negatively impacts agriculture
• Reduced native biodiversity
• Threat to/ loss of native species
• Damages animal/plant products

• Allelopathic
• Antagonistic (micro-organisms)
• Competition - monopolizing resources
• Competition - shading
• Competition (unspecified)
• Herbivory/grazing/browsing
• Rapid growth
• Rooting

• Highly likely to be transported internationally accidentally
• Highly likely to be transported internationally deliberately
• Difficult to identify/detect as a commodity contaminant
• Difficult to identify/detect in the field
• Difficult/costly to control

Economic Value

The foliage of B. ischaemum is grazed by cattle, sheep and other hoofed mammalian herbivores and provides some economic value. It is however, usually considered less productive and desirable for forage than other grasses that are widely available. This species has also been proposed as a potential species for biofuel production (Porensky et al., 2014).

Environmental Services

B. ischaemum helps stabilize soils.