Authors: Tunyalee Martin, Global Invasive Species Team, The Nature Conservancy
Tribolium obliterum (Hemsl.) Renvoize
The genus name, Tribolium, was derived from the Latin tri, meaning three and bolus, meaning a fiery meteor in the form of an arrow. The genus name was possibly in reference to the bristly glumes surrounding the 3 florets (Hubbard 2001). Synonyms for Tribolium obliterum are numerous including "Brizopyrum glomeratum" and "Poa glomerata". See the Missouri Botanical Gardens website (Anonymous 2001a) for a complete list. The common name "Cape grass" was coined by Hrusa (Hrusa 2001).
Tribolium obliterum (Hemsl.) Renvoize is a non-native grass believed to have arrived in California as an ornamental. The Plant Diagnostics Center of the California Department of Food and Agriculture has given the plant a Q rating, meaning that it is a quarantine plant and will be intercepted if sold in the U.S. until further evaluation. The quarantine rating is primarily because the behavior of the plant is unknown at this time (Hrusa 2001). The identification of T. obliterum from Fort Ord, near Monterey is a first for California and for North America. Although its impact on wild lands is unknown, it has been found to be spreading in the Fort Ord area.
Patches now occur in a 3 by 1.5 km area of maritime chaparral that has signs of disturbance from army use. Tribolium obliterum may grow by itself, or hidden among other plants making it difficult to detect (Hubbard 2001).
The impacts of this new invader are not yet known. In disturbed sites the impact of T. obliterum is minimal, but it may compete with native bunchgrasses where they grow together (Hubbard 2001). Other species in the genus Tribolium can be agricultural weeds, but are not considered invasive in natural areas (Hrusa 2001).
Tribolium obliterum (Hemsl.) Renvoize is a perennial grass (Poaceae). It has decumbent or erect culms 12-40 cm long, with 3-4 nodes (Linder & Davidse 1997). The leaf blades are linear and narrow, 0.5-1 mm wide and 1-8 cm long (Linder & Davidse 1997), without cross venation. Plants in the genus Tribolium are bisexual with bisexual spikelets and hermaphrodite florets (Watson & Dallwitz 1992). It its native range, flowering occurs in the spring (September - November) (Anonymous 2001b). The fruit (caryopsis) is small, 1-2 mm in length, yellow-brown in color, obovate, and compressed dorsiventrally (Watson & Dallwitz 1992). In California, stolons were observed on some plants during the winter, but did not appear to be rooting or producing new plants (Hubbard 2001).
Tribolium obliterum is native to South Africa. The genus contains ten species that occur in the Fynbos and Karoo and commonly are adventive (Watson & Dallwitz 1992). Tribolium obliterum is typically found at low altitudes on gravelly, well-drained soils (Linder & Davidse 1997).
Tribolium obliterum is an invader in one small site in California (USA), and at sites in Australia, and on St. Helena and Ascension Islands in the Atlantic. There are no reports of it spreading rapidly in these areas (Linder & Davidse 1997). The California Tribolium obliterum population is spreading in an eroded gully and in a restoration site where the soil was disturbed. Species in the genus Tribolium are mesophytic to xerophytic, common in open habitats, and do not like salty soils (Watson & Dallwitz 1992). Susan Hubbard (Hubbard 2001) has observed that T. obliterum prefers clear, flat areas and has been found along dirt roads and in other disturbed areas. Seeds may be spread by water. In Fort Ord, plants have been found in water channels and places where water is expected to run.
Seeds may be spread by water. In Fort Ord, plants have been found in water channels and places where water is expected to run. Although stolons were observed, they did not appear to be rooting or producing new plants. It is still unknown whether T. obliterum can spread by vegetative growth (Hubbard 2001).
- Digging the plant up with a shovel has been effective.
- Glyphosate (Roundup) appears to be effective (although non-selective) against T. obliterum. Applications made with 2% glyphosate appear to be successful. In the future follow-up applications may be necessary.
- The infestation at Fort Ord in California appears to be associated with disturbed areas. Minimizing disturbance to natural areas may help prevent establishment.
Anonymous 2001a. , accessed 4/2001.
Hrusa, G.F. 2001. Senior Plant Systematist in the Herbarium of the Plant Pest Diagnostics Center, California Department of Food and Agriculture. Personal communication.
Hubbard, S. 2001. Bureau of Land Management at Fort Ord. Personal communication.
Linder, H.P. and G. Davidse. 1997. The systematics of Tribolium Desv. (Danthonieae: Poaceae)
Watson, L. and M.J. Dallwitz. 1992 onwards. Grass Genera of the World: Descriptions, Illustrations, Identification, and Information Retrieval; including Synonyms, Morphology, Anatomy, Physiology, Phytochemistry, Cytology, Classification, Pathogens, World and Local Distribution, and References. (broken link) Version: 18th August 1999.