Tragus racemosus
(stalker bur grass)

Preferred Common Name

• stalker bur grass

Other Scientific Names

• Cenchrus racemosus L.
• Lappago decipiens Fig. & De Not.
• Lappago racemosa (L.) Honck.
• Nazia racemosa (L.) Kuntze
• Tragus adriaticus Gand.
• Tragus arenarius Bremek. & Oberm.
• Tragus brevicaulis Boiss.
• Tragus decipiens (Fig. & De Not) Boiss.
• Tragus echinatus Cav.
• Tragus pallens Gand.
• Tragus paucispinus Hack.

International Common Names

• English: carrot seed grass; European bur grass; large carrot-seed grass; spike bur grass

Local Common Names

• Cuba: rabo de gato
• France: tragus à grappes
• Germany: Klettengras
• Italy: lappola
• South Africa: wortelsaadgras
• Spain: cerretes; escanyyagats; grama enmarañada
• Sweden: piprensargräs

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

Tragus is a genus in the Poaceae family with seven to eight accepted species, mostly tropical and subtropical (Anton, 1981; World Flora Online, 2020). The genus is characterized by having a disarticulating inflorescence, a rudimentary first glume and an awnless second glume with distinctive prickles or spines on its nerves (Anton, 1981).

The genus name Tragus comes from the Greek word ‘tragos’ meaning he-goat and the specific epithet ‘racemosus’ refers to the racemose inflorescence (SEINet, 2020). Of the synonyms reported for T. racemosus, Aira malatrina, Cenchrus linearis, Lappago biflora, Phalaris muricata, T. biflorus and T. muricatus are invalid names; T. halleri and T. orientalis are illegitimate names (World Flora Online, 2020).

The following description is from PROTA (2020):

Annual up to 25 cm tall, erect or geniculately ascending; leaf laminas 2-6 cm × 1.5-4.5 mm, flat or plicate, glaucous, the margins thickened, whitish, pectinate with bulbous-based hairs or barbellate. Inflorescence 2.5-6 cm long, compactly cylindrical, congested; racemelets comprising (1)2-4 fertile and (1)2 sterile spikelets borne on a short peduncle. Spikelets 3.2-4 mm long; superior glume prominently 7-nerved, the nerves bearing hooked, bulbous-based prickles, glabrous between the nerves; anthers 0.5-0.7 mm long.

Tragus racemosus is reported as present in Belgium prior to 1850, as a common wool alien from 1887 to 1947. In recent times, it has been found in disturbed sites near railways (Alien plants of Belgium, 2020) and reported to be spreading rapidly in southern Europe, with stable populations found in northern France. Diaspores of T. racemosus were introduced into the Czech Republic with wool into local woollen mills, and spread to the surrounding areas via wool waste (Kaplan et al., 2015). Although T. racemosus is reported as native to Africa, it is listed in Libya as both native and introduced (El-Gadi et al., 1987).

In the USA, T. racemosus has been reported since the late 1800s in the northeast as a ballast waif and as growing in dumps of wool carding factories (Knowlton et al., 1913; Pohl, 1947; Native Plant Trust, 2020). It has spread to the western USA from Arizona to Texas and in the eastern USA from Maine to North Carolina, but without details given (Reed, 1954). According to SEINet (2020), the species was collected in Maine, Pennsylvania, New York and North Carolina in the late 19th century, but is no longer present in those states. It is considered as an occasional anthropogenic weed in eastern USA (Native Plant Trust, 2020). From its distribution in the western USA, some of the reports for New Mexico and Texas appear to be misidentifications of T. berteronianus (SEINet, 2020). In the New World, it is also known to occur in South America since the mid-1800s and in the Caribbean in the 1950s (Proctor, 1982; Missouri Botanical Garden, 2020).

Soil drainage

• free

Soil texture

• heavy
• light
• medium

Special soil tolerances

• infertile

Natural Dispersal

Although the seeds of T. racemosus have hooked spines adapted for animal dispersal, Catasús Guerra (2015) also reports the species as being wind dispersed.

Vector Transmission (Biotic)

Tragus racemosus seeds have hooked spines adapted for animal dispersal (Freund et al., 2014; Catasús Guerra, 2015; Shabana et al., 2018; PROTA, 2020).

Accidental Introduction

Tragus racemosus has been accidentally introduced to various countries as a contaminant of wool products and waste (Parlin, 1904; Alien plants of Belgium, 2020; SEINet, 2020). It is also reported as introduced in ship ballast (Angelo and Boufford, 1998; Native Plant Trust, 2020).

Tragus racemosus is reported as causing severe 'seedy wool' problems on sheep farms in Africa and as a potential seed contaminant, but without further details given (PROTA, 2020). In France, in the Haute Provence region, this species is regarded as a weed, and reported as aggressively carpeting lavender fields during summer after they have been cleared of weeds in early summer (Bogaard et al., 2020). Although predicted to have low competitive ability and not an important weed in the organic arable fields of Provence, T. racemosus is considered an effective, and increasing, summer-annual colonist of fallow sites where existing annual vegetation has been removed in spring or early summer (Bogaard et al., 2020).

There are no details about the impact of T. racemosus on other species; according to Catasús Guerra (2015) it can outcompete other species in dry and nutrient-poor habitats.

• Proved invasive outside its native range
• Has a broad native range
• Pioneering in disturbed areas
• Fast growing
• Has propagules that can remain viable for more than one year

• Damages animal/plant products

• Competition - monopolizing resources
• Rapid growth
• Produces spines, thorns or burrs

• Highly likely to be transported internationally accidentally

Social Benefit

Tragus racemosus is occasionally grazed by sheep, cattle and camels (Ali et al., 2009; PROTA, 2020); due to its short cycle and low seed yield, it is not actively used for forage. The seeds are listed as used in porridges but without further details (PROTA, 2020).

Environmental Services

The presence of T. racemosus is generally indicative of a denuded field in an early successional stage (PROTA, 2020). It may be used as a cover crop to prevent soil erosion (Bogaard et al., 2020).