''Rottboellia cochinchinensis'' is a species of

grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...

known by the common names Itchgrass,Holm, L. G., Plucknett, D. L., Pancho, J. V., & Herberger, J. P. (1977). The world’s worst weeds. The World’s Worst Weeds.Smith, M. C., Reeder, R. H., & Thomas, M. B. (1997). A Model to Determine the Potential for Biological Control of Rottboellia cochinchinensis with the Head Smut Sporisorium ophiuri. The Journal of Applied Ecology, 34(2), 388. https://doi.org/10.2307/2404884 Raoul grass,Lencse, R. J., & Griffin, J. L. (1991). Itchgrass ( Rottboellia cochinchinensis ) Interference in Sugarcane ( Saccharum sp .) Weed Science. 5(2), 396–399. corngrass,Hafliger, E., & Scholz, H. (1980). Grass weeds I. Weeds of the subfamily Panicoideae. Grass Weeds I. Weeds of the Subfamily Panicoideae. Kokoma grass, Guinea-fowl grass, jointed grass, Shamwa grass and Kelly grass.GBIF Secretariat (2019) Rottboellia cochinchinensis (Lour.) Clayton GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei https://www.gbif.org/species/2704075 ccessed on 08 October 2019/ref> It is a tall, tufted

annual Annual may refer to: *Annual publication, periodical publications appearing regularly once per year ** Yearbook ** Literary annual *Annual plant *Annual report *Annual giving *Annual, Morocco, a settlement in northeastern Morocco *Annuals (band), ...

grass whose stems ( culms) grow up to in height with leaf-blades of up to in length.Clayton, W.D., Vorontsova, M.S., Harman, K.T. and Williamson, H. (2006). GrassBase - The Online World Grass Flora. http://www.kew.org/data/grasses-db.html. ccessed 08 October 2019/ref> The species flowers at the apex of culms in the form of spike-like

racemes A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...

composed of paired spikelets. The common name Itchgrass comes from the bristly (hispid) leaf-sheath which can be irritating to the skin. ''Rottboellia cochinchinensis'' is native to tropical

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

and

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

and has also been introduced to the Americas where it is often considered to be an invasive species.Clayton, W. D. (1980). Notes on the Tribe Andropogoneae ( Gramineae ) Kew Bulletin, 35(4), 813–818. It is a major

weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...

of a wide range of crops including

maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...

rice Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and '' Porteresia'', both wild and domesticat ...

, sorghum and

sugar cane Sugarcane or sugar cane is a species of (often hybrid) tall, perennial grass (in the genus '' Saccharum'', tribe Andropogoneae) that is used for sugar production. The plants are 2–6 m (6–20 ft) tall with stout, jointed, fibrous stalk ...

.Bolfrey-Arku, G. E.-K., Chauhan, B. S., & Johnson, D. E. (2011). Seed Germination Ecology of Itchgrass ( Rottboellia cochinchinensis ) . Weed Science, 59(2), 182–187. https://doi.org/10.1614/ws-d-10-00095.1

Description

''Rottboellia cochinchinensis'' is an

with prop roots supporting erect, laterally-branching culms which are usually between 30–300 cm in length, although up to 400 cm high culms have been described.Cope, T. A. (2002). Rottboellia L.f. In G. V. Pope & E. S. Martins (Eds.), Flora Zambesiaca (pp. 174–176). London: Royal Botanic Gardens, Kew. Cauline leaves arise from hispid leaf-sheaths with irritating hairs, especially on the lower sheaths. The leaf-sheaths are as wide as the blade at the collar and have a truncated, membranous ligule of 1mm in length. The leaf blades are slightly rough (scabridulous) and are generally linear to linear-lanceolate, terminating in an acuminate apex.Beentje, H. (2016). Plant Glossary: an illustrated dictionary of plant terms. Kew Publishing The leaves are usually between 15–45 cm long and 5-20mm wide, although larger dimensions of 80 cm long and 45mm wide have been suggested as upper limits. The

of ''R. cochinensis'' are 3–15 cm long, cylindrical, hairless (glabrous), erect and are found on terminal and axillary culms. Each raceme is either embraced at the base by, or projects beyond, a leaf arising from an inflated leaf-sheath. The peduncle at the base of each raceme is rough and widens as it approaches its apex, where the raceme is divided by fragile nodes between each

rachis In biology, a rachis (from the grc, ῥάχις [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this c ...

. The rachides are strongly inflated at around 2–3.5mm wide and 5-7mm between each node and bear pairs of

spikelet A spikelet, in botany, describes the typical arrangement of the flowers of grasses, sedges and some other Monocots. Each spikelet has one or more florets. The spikelets are further grouped into panicles or spikes. The part of the spikelet that ...

s abaxially: one sterile and attached with a pedicel fused to the internode, the other fertile and attached directly (sessile).Veldkamp, Koning, & Sosef. (1986). Generic Limitation of Rottboellia and Related Genera. 31, 281–307. The raceme tapers off with a number of reduced, sterile spikelets at the apex, which form a false panicle as they appear to be much-branched. The sterile, pedicelled spikelet in each pair is well developed at about 3-5mm long and is egg-shaped and dorsally flattened. The spikelet is enclosed by bracts called

glumes In botany, a glume is a bract (leaf-like structure) below a spikelet in the inflorescence (flower cluster) of grasses (Poaceae) or the flowers of sedges (Cyperaceae). There are two other types of bracts in the spikelets of grasses: the lemma and ...

which are hardened, smooth, obtuse, blunt, distinctly veined, glabrous and winged on the margins. The sterile spikelet is deciduous with the fertile spikelet, meaning they break off together with a central peg where the pair were attached transversely at each rachis node. The fertile, sessile spikelets are very similar to the sterile spikelets, being around 3.5-5mm long, ovate and dorsally flattened, although they are attached differently to the rachis. The glumes of these spikelets are dissimilar as the lower one is wider than the upper and is not winged, whereas the upper is V-shaped. The lower glume has 13 veins and is 2-keeled, unlike the upper which is 11-veined and singularly keeled. Both reach the apex of the florets but the lower glume apex is notched (emarginate) whereas the upper is acute. As with most members of the Poaceae family, the fertile spikelets contain florets with two

lodicule A spikelet, in botany, describes the typical arrangement of the flowers of grasses, sedges and some other Monocots. Each spikelet has one or more florets. The spikelets are further grouped into panicles or spikes. The part of the spikelet that ...

s, fleshy scales which open the glumes during flowering. These lodicules are the same size as the 3 anthers present in the florets at 2mm long and within them are the female parts of the flower consisting of 2 stigmas. Also typically for the Poaceae, the fruit formed is a single seed fused to the

pericarp Fruit anatomy is the plant anatomy of the internal structure of fruit. Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Aggr ...

called a

caryopsis In botany, a caryopsis (plural caryopses) is a type of simple fruit—one that is monocarpellate (formed from a single carpel) and indehiscent (not opening at maturity) and resembles an achene, except that in a caryopsis the pericarp is fuse ...

, although in ''R. cochinchinensis'' the pericarp becomes free with time. The caryopsis is 3.5mm in length with the embryo around half the total length. The hilum, the scar where the caryopsis attached to the placenta, is point-like (punctiform) and the endosperm is covered with a mealy powder (farinose). The caryopsis is then disseminated with the rachis internode and a structure called the eliastome (callus knob) still attached. ''Rottboellia cochinchinensis'' has been found to vary in

chromosome number Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectivel ...

, with diploid cells having either 20, 36, 40 or 60 chromosomes, so either x=10 or sometimes x=9 are common basic numbers.Millhollon, R. W., & Burner, D. M. (1993). Itchgrass ( Rottboellia cochinchinensis ) Biotypes in World Populations. Weed Science, 41(3), 379–387. https://doi.org/10.1017/s0043174500052085Kellogg, E. A., & Kubitzki, K. (2015). Flowering plants. Monocots: Poaceae. In Flowering Plants. Monocots: Poaceae. https://doi.org/10.1007/978-3-319-15332-2

Etymology

The genus ''Rottboellia'' was named in honour of the Danish botanist

Christen Friis Rottbøll Christen Friis Rottbøll (3 March 1727, at Hørbygård, Denmark – 15 June 1797, in Copenhagen) was a Danish physician and botanist: He was a pupil of Carolus Linnaeus. Early life Rottbøll was born on the Hørbygaard estate at Holbæk, the so ...

(1727–1797) by

Carl Linnaeus the Younger Carl Linnaeus the Younger, Carolus Linnaeus the Younger, Carl von Linné den yngre ( Swedish; abbreviated Carl von Linné d. y.), or ''Linnaeus filius'' ( Latin for ''Linnaeus the son''; abbreviated L.fil. (outdated) or L.f. (modern) as a botan ...

in 1781 in the publication ''Supplementum Plantarum.''Linnaeus, C. (1781). Supplementum Plantarum Part 2. Supplementum Plantarum, 126–127. The species epithet ''cochinchinensis'' traces its etymology back to the basionym ''Stegosia cochinchinensis'', which was used by

João de Loureiro João de Loureiro (1717, Lisbon – 18 October 1791) was a Portuguese Jesuit missionary and botanist. Biography After receiving admission to the Jesuit Order, João de Loureiro served as a missionary in Goa, capital of Portuguese India (3 y ...

to denote the specimen he described being from Cochinchina, now part of

Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...

.Loureiro, J. de (1790). Flora Cochinchinensis, v. 1. In Flora cochinchinensis (Vol. 1).Clifford, H.T. & Bostock, P.B. (2007) Etymological Dictionary of Grasses. Springer, Germany. Clayton proposed the name ''Rottboellia cochinchinensis'' as a new combination for the species named ''Rottboellia exaltata'', now as synonym of ''R. cochinchinensis''. Due to a mistake by Linnaeus the Younger and the strict laws of

nomenclature Nomenclature (, ) is a system of names or terms, or the rules for forming these terms in a particular field of arts or sciences. The principles of naming vary from the relatively informal conventions of everyday speech to the internationally ag ...

, the widely used ''R. exaltata'' combination had to be controversially discarded.Simon, B. K. 1982. (667) Proposal to conserve the species name Rottboellia exaltata L. f. (Poaceae). Taxon 31:564-565

Habitat and ecology

''Rottboellia cochinchinensis'' uses C4 carbon fixation during

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

and as such is mostly found in warm

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

climates Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorological ...

with high sunlight, generally in the tropics and between the northern and southern 20 °C isotherms.Strahan, R. E., Griffin, J. L., Reynolds, D. B., & Miller, D. K (2019). Interference between Rottboellia cochinchinensis and Zea mays. Weed Science Society of America. 48(2), 205–211.Spaunhorst, D. J., & Orgeron, A. J. (2019). Dry Heat and Exposure Time Influence Divine Nightshade and Itchgrass Seed Emergence. Agronomy Journal, 111(5), 2226. https://doi.org/10.2134/agronj2019.02.0072 Carbon fixation by this pathway allows plants to avoid the wasteful process of

photorespiration Photorespiration (also known as the oxidative photosynthetic carbon cycle or C2 cycle) refers to a process in plant metabolism where the enzyme RuBisCO oxygenates RuBP, wasting some of the energy produced by photosynthesis. The desired reaction ...

and as such confers a competitive advantage to species such as ''R. cochinchinensis'' in high light intensity, high heat and low humidity conditions over C3 plants. The species can be found in a diverse array of habitats including

grassland A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...

and

marginal land Marginal land is land that is of little agricultural or developmental value because crops produced from the area would be worth less than any rent paid for access to the area. Although the term ''marginal'' is often used in a subjective sense for l ...

, as well as being a major weed of

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wid ...

and rotation crops across the tropics. Globally there are least 18 crop species where ''R. cochinchinensis'' is considered an important weed including sugarcane (''

Saccharum ''Saccharum'' is a genus of tall perennial plants of the broomsedge tribe within the grass family. The genus is widespread across tropical, subtropical, and warm temperate regions in Africa, Eurasia, Australia, the Americas, and assorted oceani ...

''),

('' Zea''),

upland rice Upland rice is a type of rice grown on dry soil rather than flooded paddy field, rice paddies. It is sometimes also called dry rice. Introduction Today nearly 100 million people depend on upland rice as their daily staple food. Almost two-thi ...

(''

Oryza ''Oryza'' is a genus of plants in the grass family. It includes the major food crop rice (species ''Oryza sativa'' and ''Oryza glaberrima''). Members of the genus grow as tall, wetland grasses, growing to tall; the genus includes both annual an ...

''),

cotton Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor pe ...

(''

Gossypium ''Gossypium'' () is a genus of flowering plants in the tribe Gossypieae of the mallow family, Malvaceae, from which cotton is harvested. It is native to tropical and subtropical regions of the Old and New Worlds. There are about 50 ''Gossypium ...

''),

soy The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean, which has numerous uses. Traditional unfermented food uses of soybeans include soy milk, from which tofu and ...

(''

Glycine Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid ( carbamic acid is unstable), with the chemical formula NH2‐ CH2‐ COOH. Glycine is one of the proteinog ...

''), '' Sorghum'' and

peanut The peanut (''Arachis hypogaea''), also known as the groundnut, goober (US), pindar (US) or monkey nut (UK), is a legume crop grown mainly for its edible seeds. It is widely grown in the tropics and subtropics, important to both small and ...

s (''

Arachis ''Arachis'' is a genus of about 70 species of annual and perennial flowering plants in the family (Fabaceae), native to South America, and was recently assigned to the informal monophyletic ''Pterocarpus'' clade of the Dalbergieae. At least one ...

''). Asian countries such as

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

do not seem to suffer from ''R. cochinchinensis'' as such a serious weed, suggesting that certain biotypes of the species are more vigorously

competitive Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...

with crops than others. ''Rottboellia cochinchinensis'' is relatively

shade tolerant In ecology, shade tolerance is a plant's ability to tolerate low light levels. The term is also used in horticulture and landscaping, although in this context its use is sometimes imprecise, especially in labeling of plants for sale in commercial ...

, and also able to grow rapidly under high light exposure. The species is usually found at

altitudes Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...

up to 2300m, with low temperatures often being the

limiting factor A limiting factor is a variable of a system that causes a noticeable change in output or another measure of a type of system. The limiting factor is in a pyramid shape of organisms going up from the producers to consumers and so on. A factor not l ...

above this, and favours acidic soils. It flowers all year long in tropical climates, but during July and August in the US and is a prodigious seed producer, sometimes producing over 2000 seeds per plant (although not all would be viable) and over 650 kg per hectare.

Seed germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fern ...

patterns are unclear and vary across the

pantropical A pantropical ("all tropics") distribution is one which covers tropical regions of both hemispheres. Examples of species include caecilians, modern sirenians and the plant genera ''Acacia'' and ''Bacopa''. ''Neotropical'' is a zoogeographic term ...

distribution of ''R. cochinchinensis,'' and recent research is aiming to better understand seedling emergence patterns in order to inform control regimes.Leon, R. G., Izquierdo, J., & Gonzalez-Andujar, J. L. (2015). Characterization and Modeling of Itchgrass (Rottboellia cochinchinensis) Biphasic Seedling Emergence Patterns in the Tropics. Weed Science, 63(3), 623–630. They are dispersed by floodwater, birds, small mammals and latterly by humans and vehicles. The eliastome (callus knob) which is disseminated with the caryopsis, contains oils which may attract ants and aid dispersal.Veldkamp, Koning & Sosef. (1986). Generic Limitation of Rottboellia and Related Genera. 31, 281–307.

Distribution

The natural distribution of ''R. cochinchinensis'' is somewhat unclear as the species seems to have been very successful at growing its range.Alves, E. C. C., Silva, M. A. S., Moro, F. V. Luís, P., Bachega, M. F., Moro, J. R., F, M. V., (2019). Identification and Characterization of Different Accessions of Itchgrass ( Rottboellia America 51(2), 177–180. Most sources assume the species is native to

South-East Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainland ...

, as it was first described from specimens found in this area, although some sources cite India. It is now pantropical in distribution, being found across the Old World tropics from southern Asia, Sub-Saharan Africa,

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

and

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torr ...

and the

Solomon Islands Solomon Islands is an island country consisting of six major islands and over 900 smaller islands in Oceania, to the east of Papua New Guinea and north-west of Vanuatu. It has a land area of , and a population of approx. 700,000. Its capit ...

, and Australia as far as

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , establishe ...

,Plants of the World Online , Rottboellia cochinchinensis (Lour.) Clayton , Kew Science. (n.d.). Retrieved October 10, 2019, from http://www.plantsoftheworldonline.org/taxon/urn:lsid:ipni.org:names:909653-1 with one georeferenced record from

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

.BioNet Atlas of NSW Wildlife:SRXLI0013904 , Occurrence record , Atlas of Living Australia. (n.d.). Retrieved October 10, 2019, from https://biocache.ala.org.au/occurrences/613cf229-2a51-44b0-8106-8c39c83fbe95 In addition, it has been widely introduced across the tropical

Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...

, possibly first to

Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

but rapidly spreading across the Caribbean, southern

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

and across tropical Central and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

. Introductions are speculated to have originated from the transportation of crop products and agricultural and forestry machinery,Veldman, J. W., & Putz, F. E. (2019). Long-distance Dispersal of Invasive Grasses by Logging Vehicles in a Tropical Dry Forest Author ( s ): Joseph W . Veldman and Francis E . Putz Published by : Association for Tropical Biology and Conservation Stable URL : https://www.jstor.org/stable/40891. 42(6), 697–703. or even intentionally introduced for grazing in the Caribbean

Taxonomy and systematics

The

taxonomic classification In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are give ...

of ''Rottboellia cochinchinensis'' is largely still based on the work of Clayton and Renvoize in 1986, who placed the genus within the Andropogoneae tribe of the Panicoideae, which is a subfamily within the Grasses (Family: Poaceae).Clayton, W. D., & Renvoize, S. A. (1986). Genera graminum. Grasses of the World. Genera Graminum. Grasses of the World., 13. The tribe was defined morphologically by many characters including fragile racemes, subtended by a leaf-sheath, which bear pairs spikelets, one fertile and sessile and the other pedicelled and barren. Like many members of the tribe, the pairs of spikelets in ''R. cochinchinensis'' fall together with the internode at maturity. From this classification, the genus ''Rottboellia'' was thought to have evolved from a common ancestor with the ''Phacelurus'' and ''Coelorachis'' genera, with ''Rottboellia'' forming a sister clade to ''Zea''. Clayton and Renvoize also recognised a subtribe Rottboelliinae which included the genera Coelorachis, Hackelochloa, Hemarthria and Elionurus, amongst others More recent evaluations of the Andropogoneae.Skendzic, E. M., Travis Columbus, J., & Cerros-Tlatilpa, R. (2007). Phylogenetics of Andropogoneae (Poaceae: Panicoideae) Based on Nuclear Ribosomal Internal Transcribed Spacer and Chloroplast trnL-F Sequences. In Aliso: A Journal of Systematic and Evolutionary Botany (Vol. 23).Teerawatananon, A., Jacobs, S. W. L., & Hodkinson, T. R. (2010). Phylogenetics of Panicoideae (Poaceae) based on chloroplast and nuclear DNA sequences. Telopea, 13(1–2), 115–142.Soreng, R. J., Peterson, P. M., Romaschenko, K., Davidse, G., Zuloaga, F. O., Judziewicz, E. J., … Morrone, O. (2015). A worldwide phylogenetic classification of the Poaceae (Gramineae). Journal of Systematics and Evolution, 53(2), 117–137. https://doi.org/10.1111/jse.12150Soreng, R. J., Peterson, P. M., Romaschenko, K., Davidse, G., Teisher, J. K., Clark, L. G., … Zuloaga, F. O. (2017). A worldwide phylogenetic classification of the Poaceae (Gramineae) II: An update and a comparison of two 2015 classifications. Journal of Systematics and Evolution, 55(4), 259–290. https://doi.org/10.1111/jse.12262 have found evolutionary relationships between the constituent genera more difficult to tease out.

Phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

methodologies have experienced difficulties in resolving evolutionary relationships within the tribe, and have pointed to rapid basal radiation and/or frequent hybridisation within the clade as possible causes. However, the merger of the genera ''Rottboellia'' and ''Coelorachis'' has been well supported. Skendzic et al. (2007) also has Hackelochloa, Hemarthria and Elionurus as sister genera within Rottboelliinea sensu Clayton and Renvoize (1986)

Additional information

Archaeological evidence of a ''Rottboellia cochinchinensis'' caryopsis from an

Early Iron Age The Iron Age is the final epoch of the three-age division of the prehistory and protohistory of humanity. It was preceded by the Stone Age (Paleolithic, Mesolithic, Neolithic) and the Bronze Age (Chalcolithic). The concept has been mostly appl ...

site on the

Lulonga River The Lulonga is a river in the Equateur province of Democratic Republic of the Congo. It is about 200 km long from its beginning at the town of Basankusu. The Lopori and the Maringa join to form the Lulonga there. The Lulonga River flows i ...

in the

Democratic Republic of Congo The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...

was found in the early 2010s, possibly suggesting the species native distribution covers the Old World Tropics.Kahlheber, S., & Eggert, M. K. H. (2014). Pearl Millet and Other Plant Remains from the Early Iron Age Site of Boso-Njafo (Inner Congo Basin , Democratic Republic of the Congo ) The African Archaeological Review 31(3), 479–512. African communities have been known to use leaves and culms to produce mats.

References

{{Taxonbar, from=Q15057501 Panicoideae