Bermuda+Grass+(Cynodon+dactylon)

//Cynodon dactylon// (L.) Pers., 1805
 * Bermuda Grass **

toc =The Bermuda Grass, a short introduction.= Revered as a sacred grass in India, this grass has an extensive history worldwide and a wide array of functions (from an anti-erosion soil cover to a medicine treating cramps and snakebite) to boast. It also has superb high resilience to numerous environmental conditions that allows it to even brace through drought, forest fires and floods. Its remarkable hardiness has allowed it to survive and spread to many regions in the world. You can easily identify the Bermuda grass by its purple inflorescence during bloom (Figure 1). Its presence could mean delight to lawn and turf owners for its attractive and luscious grass spread, but also hint disaster to agriculturists as it is, at the same time, a very hardy weed. Whichever the case, the Bermuda grass has the potential to influence the economy and ecology of where it spreads to, as it is currently one of the world's most serious weeds and an invasive species in many countries including Singapore.



Can you tell which is the Bermuda Grass?
How often do you notice the type of grasses that you step on? Here are three grasses in Singapore, do you recognise them? Can you tell which is the Bermuda grass? Figure 2. (own photo) ||  Figure 3. (own photo) || Figure 4. (own photo) ||
 * || Type 1 || Type 2 || Type 3 ||
 * Grass: || [[image:https://4.bp.blogspot.com/-uyiZQtRlfK8/WClmiChOqxI/AAAAAAAAAg4/EerERsxrQh0pOuS9nGWPy86gstOfUai7wCEw/s320/zcowgrass.jpg width="256" height="256"]]
 * Identity: || Cow grass (//Axonopus compressus//) || Bermuda grass (//Cynodon dactylon//) || Manila grass (//Zoysia matrella//) ||

In Singapore, the grass cover is mostly occupied by the coarse //Axonopus compressus// (cow grass), which is one of the cheapest type for turfing (priced at $4 to $6 per square metre). The //Zoysia// sp//.// on the other hand is much pricier (priced at $8 to $12 per square metre) and not commonly seen in public green areas [3] **.** However, along with the abovementioned, there are plenty of other grass species found along walkways and green areas in Singapore, and the Bermuda grass is one of them!

One of the simplest way to tell species of grass apart is through their inflorescence. Differentiating Bermuda grass from other apparently similar looking greens is not so difficult if you look for its distinctive purple inflorescence (Figure 5). An inflorescence of a plant means a cluster of flowers joined to a branch, or an arrangement of branches. Bermuda grass inflorescence normally has its spikes arranged at the apex tip of the ** culm ** as seen in Figure 5. Another way of differentiating the Bermuda grass is to look at its ** ligules **. Bermuda grass is known to have white hairs growing from its ligules (Figure 6).



However, identifying Bermuda grass is not easy sometimes as there are several other similar looking species around. Worldwide, these species include //C. nlemfuensis// (African Bermuda grass)//, C. plectostachyus// (Giant star grass)//, C. aethiopicus// (Ethiopian dog tooth grass), //Digitaria sanguinalis// (L.) Scop. (Large crabgrass), //Eleusine indica// (goosegrass), and //Paspalum dilatatum// Poir (dallisgrass). In Singapore, similar looking inflorescence includes those of the goosegrass (Figure 8) and cow grass (Figure 9). Figure 7. (own photo) || Figure 8. (own photo) || Figure 9. (own photo) ||
 * || Bermuda grass || Goose grass || Cow grass ||
 * Inflorescence: || [[image:https://3.bp.blogspot.com/-S3DUbKKxT1E/WClm_jEeScI/AAAAAAAAAg8/RRzd9Jr6bMQHe0fC1C2SqyxiSKcl14jWgCLcB/s320/IMG_1765.JPG width="240" height="320" link="https://3.bp.blogspot.com/-S3DUbKKxT1E/WClm_jEeScI/AAAAAAAAAg8/RRzd9Jr6bMQHe0fC1C2SqyxiSKcl14jWgCLcB/s1600/IMG_1765.JPG"]]

Life of the Bermuda Grass
__**The amazing range of conditions it can survive in**__ Bermuda grass can thrive on a diversity of soil types and an amazing range of environmental condition. The annual temperature range for survival can range from 5.9 to 27.8°C, while pH can range from 4.3 to 8.4, spanning acidic and alkali soils. It can even also survive in soils with high salt concentration. In addition, the grass can tolerate high temperatures as well as dry conditions by going into ** dormancy ** that can last up to seven months while using its ** rhizomes ** for survival. Not only does it tolerate droughts, the Bermuda grass can also withstand fires, floods and frequent grazing ! The rhizomes and deep underground network of the Bermudagrass is believed to avoid annihilation during grassland fires that are quick and do not burn deep enough to destroy rootstocks. The grass can quickly recover after a fire and also brace through several weeks of deep flooding, and then easily re-sprout from ** stolons ** and rooted** runners **.

Despite its robustness in several extreme environmental conditions, the grass is a full sun plant which makes it vulnerable to shade and susceptible to prolonged frost[4]. The Bermuda grass is best adapted to relatively fertile and well-drained soil in humid areas with moderate warmth and soil of pH 6-7[6].

** __When does it flower?__ ** Flowering occurs throughout the year in warmer regions [6]. Having a ** photoperiod ** of 13 hours will induce flowering, which if followed by low night temperatures with a big difference in day and night temperatures will induce blooming. ** Irradiance ** is also important for flowering as reduced irradiance would drastically reduce inflorescence production.

**__How does it pollinate?__** The Bermuda grass is wind-pollinated and but self-pollination can negatively affect seed and forage yields [10].

**__How does it disp____erse?__** The Bermuda grass propagates by two main methods: the seeds and the stolons. Seeds are light and can be carried easily by wind, water and animals [7]. Its seeds are also eaten by animals and excreted. Stolons can be propagated via agricultural or cultivation practices such as chisels and drilling equipment that would help stolon fragments get distributed away from the original site [4].

Being easily dispersed is one trait that allows the Bermuda grass to propagate to many locations, and its hardiness is another important factor for its worldwide establishment at places suitable for survival. Check out its distribution below!

Distribution
The grass can be found in temperate, subtropical and tropical regions worldwide, growing along sea coasts in temperate zones, along rivers and on irrigated land in arid zones, and in areas with 670-1750mm rainfall in tropical zones [6]. The global distribution recorded can be seen below (Figure 10). The Bermuda grass ( //Cynodon dactylon// (L.) Pers.) probably originated in tropical Africa but its wide distribution from earlier periods have led to Australia, Eurasia, Indo-Malaysia, the Bengal region of India and Bangladesh all being considered as its place of origin [5].



What uses does the Bermuda grass have?
__**Good for Pastures**__ As Bermuda grass is resilient to a wide range of environmental conditions, having a pasture of Bermuda grass can provide more and better fodder grass as compared to other grasses especially during hot weathers and droughts [6]. This is valuable function of the Bermuda grass has even been recorded in the Veda (Hindu sacred writing) which coined the grass as the "Shield of India" and "Preserver of Nations" as it supported livestock that would have otherwise perished and people would suffer from famine [5]. They can also be grazed more intensively than what most grasses can normally endure and are also used as hay [7].

__**Good for Lawns and Turfs**__ The drought-resistant Bermuda grass can still remain green and attractive even when other grasses might have turned yellow, making them popular choices for lawn and turf grasses. The grass provides a dense, wear-resistant turf for golf courses [7] as well as a traffic-resistant turf grass that requires low maintenance. Bermuda grass is used as a lawn grass in many countries [4] and its hybrids are also less expensive to maintain and can establish more quickly than other grasses. In Singapore, the grass is frequently used in golf courses [3].

__**Good for Soil Conservation**__ With long horizontally spreading runners that root when ** nodes ** touch the ground, the deep and wide root network is valuable for soil conservation [6]. Sod with Bermuda grass is strong and resistant to soil erosion [16] and is utilised for dune stabilization and anti-erosion cover on bunds and embankments [4].

__**Cultural Uses**__ Bermuda grass holds important positions in many cultures. One of which is in India, where it is considered to be a sacred grass and celebrated in the abovementioned Vedas as the "shield of India and preserver of nations, as without it the cattle would perish". In India, where the grass is more commonly known as Doob or Durva, is used in worships and weddings. The grass is an important offering to the Hindu god Lord Ganesh where a minimum of 21 Durvas of three to five leaflets are tied, dipped in water, and offered. Also, in certain parts of India, the Bermuda grass stolon is used to tie the fingers together in Hindu wedding ceremonies [7]. In Sotho of Lesotho, South Africa, the Bermuda grass is used as a charm and to ward off sorcery [5].

__**Medicinal Uses**__ The different uses of Bermuda grass as a folk medicine in treating different ailments in different cultures and countries have quite an extensive tale throughout the world.

In Europe, crushed leaves of the Bermuda grass are used for heartburn. The Dutch used a decoction of the root as a remedy for indigestion and a blood purifier [5]. Also, ancient Romans derived juices from its stems to use as a diuretic and astringent to stop bleeding.

In Africa, the Xhosa tribe made a lotion from Bermuda grass to treat sores and swellings. Mexican traditions believed that Bermuda grass leaves are helpful to people with high blood pressure [7]. In the Philippines, the grass is used as a diuretic and as a tonic for lung ailments [5], and in India, it is used to treat leucoderma, bronchitis, piles, asthma, tumors, and enlargement of the spleen [18].

According to Das //et al.// (2013), the Bermuda grass is used as a folk medicine for treating "diarrhea, bronchitis, anasarca, calculus, dropsy, hemorrhage, urogenital disorders, cough, headache, sores, cancer, carbuncles, convulsions, cramps, cystitis, dysentery, epilepsy, hemorrhoids, leucoderma, hypertension, hysteria, asthma, tumors, measles, rubella, snakebite, stones, tumors, warts, wounds, eye disorders weak vision, and Dandruff" [18].

Problems with the Bermuda Grass
__**Weed problems**__ Despite the hardiness of the Bermuda grass, the same characters have led it to become a weed nuisance. In lawns, Bermuda grass as weeds can form thatches that would often require intensive management [16]. Also, in cultivated lands, Bermuda grass is very difficult to eradicate [6]. The grass is listed as one of the world's most "serious" weed in agriculture and the environment that competes with important crops such as sugarcane, rice, onion, cotton and jute.

The grass is also described as an abundant weed along roadsides, on sandy wastes and sand dunes, and readily occupying available uncultivated area [6]. The spread of the grass is very difficult to control and at the same time very costly to do so. However, it is also very easy to spread if it is accidentally transported to other unintended regions via human activities. This can promotes its further spread which can be a disastrous weed problem [4].

__**Invasive problems**__ The current invaded countries by the Bermuda grass compiled in the Invasive Species Compendium data includes Singapore and regional countries (Indonesia, Cambodia, Vietnam) among many others (refer to Figure 12) [4]. The grass can occupy modified environments such as urban areas and transportation networks and can also be found in almost all kinds of crops. As it is a highly adaptable grass, there is also a high potential of its spread to areas where environmental conditions are suitable (a requirement easy to fulfill) where it has yet to establish [4]. The main invasive problems recorded for the grass are reduced agricultural yields, being toxic to some animals, and a host for pathogens and pests.

__**Other health problems**__ The Bermuda grass was reported to be ** photosensitizing ** in animals, and it also caused contact dermatitis, and hayfever in humans.

Morphology of the Bermuda Grass
__**Brief description**__ The Bermuda grass is a fast-growing ** C4 ** herbaceous ** perennial grass ** that is both ** rhizomatous ** and ** stoloniferous **. It has underground rhizomes, with creeping runners or stolons that root at nodes, and a deep root system [6].

** __Leaves__ ** Leaf blades are arranged alternately on the runners. Leaves are flat and spreading [15] and sometimes folded, measuring 2.5-20cm long, 2-6mm broad [6]. Blades are green to dull green, with fine parallel ** ribbing ** from tip to base, and a inconspicuous midrib [4].

** __Inflorescence__ ** On the inflorescence, 2-7 spikes are supported on a culm that is erect or ascending that can grow up to 40cm tall [11]. Most of the time, spikes are arranged at the apex of the culm. Spikes are 2.5-10cm long and contain numerous spikelets arranged in two rows on one face of the spike (Figure 16). The spikelets are flat, measuring 2-2.5mm long, ** awnless **  , with one floret and unequal ** glumes ** [6]. When in bloom, the inflorescence turns purple and stigmas are clearly exposed to catch pollen (Figure 1). The inflorescence has no odor, but bears a sweet mucilaginous taste [18].

** __Stem__ ** The stem of Bermuda grass is leafy, short, jointed, branched and 10-15cm tall and under favourable conditions, they may grow up to 30-46cm tall [15]. Along the stem, very short ligules (0.2-0.3mm) are found with a conspicuous fringe of white hair. [4]

** __Runners__ ** Runners of the Bermuda grass could reach 20m long [6]. They are flat or cylindrical and spread horizontally, creeping, and having nodes with ** internode ** length of about 10cm. Each node will root in the soil and and grow culms that reach up at the surface.

** __Stolons__ ** Bermuda grass stolons are one of its propagation methods and they readily root at nodes. However, the stolon branching extent is influenced by light and nutrient levels, with lesser branching at lower levels of light and nutrients [8].

** __Rhizomes__ ** Bermuda grass rhizomes are hard, scaly and measures 1.5-3.3mm in diameter. Rhizomes can be found at the surface soil, but also penetrate deep in the soil (as much as 35cm deep). Like the stolons, rhizome branching extent is also positively influenced by light and nutrient levels [8]. With both rhizomes and stolons, the grass is able to quickly fill in new areas [16].

** __Roots__ ** The root system is fibrous and perennial with root growing from nodes after culms an leaves are produced. Mature roots are yellow to brown and deteriorate through the growing season. They are continuously replaced by younger and whiter roots. Roots will grow wherever a nodes touches the ground, and this allows the grass to form a dense mat. The deep penetration of the roots and rhizomes give the Bermuda grass good tolerance to drought conditions, in which roots can go 120-150cm deep. However, most of the root mass is located 60cm under surface [18].

** __Seeds__ ** Bermuda grass produces a huge number of seeds (Figure 19), measuring around 0.25-0.30mg. The seeds are also one of the propagation methods, along with stolons, but the viability and dormancy of seeds varies greatly to ** genotype ** and conditions in which they are formed [4]. 

Taxonomy
__**Classification**__ According to the Catalogue of Life, the classification of the Bermuda grass is as follows:

**Domain**: Eukaryota **Kingdom**: Plantae **Phylum**: Tracheophyta **Class**: Liliopsida **Order**: Poales **Family**: Poaceae **Genus**: //Cynodon// **Species**: //Cynodon dactylon//

However other versions of the classification of //Cynodon dactylon// also exist, and varies in ranks higher than the family level (from phylum to order). The variations in the ranks systematic from different databases is due to the different systems used in classification by each database.

__**Etymology**__ In the scientific name //Cynodon dactylon//, the genus //Cynodon// is said to be derived from the Greek word for 'dog tooth' as the rhizome buds bore resemblance to dog fangs [7]. The "Cyn-" is from the old Greek 'kynos' (a dog), and "odon" is from the Greek 'odontos' (tooth). For the //dactylon// part of the name, it originated from the species name //Panicum dactylon// coined by Carl Linnaeus (1707-1778) in his "Species Plantarum" published in 1753. Linnaeus derived the epithet //dactylon// from the Greek word 'daktylos' meaning finger, in which the inflorescence resembles. //Panicum dactylon// was the previous species name for the Bermuda grass but was later reclassified under the genus //Cynodon// (coined and described by Louis Claude Marie Richard (1754-1821)) with a new name of //Cynodon dactylon// published under Christiaan Hendrick Persoon (1761-1836)'s "Synopsis Plantarum" in 1805, thus reaching its current accepted scientific name of //Cynodon dactylon// (L.) Pers, 1805 today [5].

__**Synonyms**__ For the list of synonyms of the Bermuda grass (currently a total of 91 synonyms listed), please browse: http://www.catalogueoflife.org/col/details/species/id/19243823

__**Vernacular Names**__ Bermuda grass, couch grass, devil grass, dog's tooth grass, quick grass, star grass, doob, duba, Indian doab, gou-ya-gen, rumput minak are among the list of common names used in different regions worldwide [4].

__**Type Specimen and Description Papers**__ The following is found in the Linnaean Herbarium :

Type species: //Panicum dactylon// (renamed //Cynodon dactylon//) Type material: Holotype (LINN 80.35) Type locality: Cultivated  Uppsala

The Bermuda grass was first described by Carl Linnaeus in 1753 in his 'Species Plantarum' Volume 1, page 58 (Figure 20). It was later then reclassified by Christiaan Hendrick Persoon in 1805 in his published 'Synopsis Plantarum', page 85 (Figure 21). __**Position of genus //Cynodon// in the phylogenetic consensus tree**__ In Liang (1997) phylogenetic consensus tree on family Poaceae, the matK sequence in the intron of the choloroplast trnK gene was sequenced for 48 species of grasses and evaluated for phylogenetic relationships above and within the family level. The matK gene was selected to study its significance in plant evolution and how different grass groups are related to this gene phylogenetically. Liang (1997) sequenced the entire DNA of the selected species with Clustal W 1.6 and found a lack of indels which eased alignment of the matK coding region. Using the Wagner parsimony method via PAUP, analyses of trees were conducted through a heuristic search with MULPARS, tree-bisection-reconnect branch swapping, and CLOSEST addition to estimate relationships and tree topology. The genus Joinvillea was used as an outgroup. Based on the most equally parsimonious trees in the heuristic search, a strict consensus tree was derived from six most parsimonious trees and bootstrapping and decay analyses were performed with PAUP to find the relative support of the clades on the tree. The different genera are represented on the consensus tree (Figure 22). According to the results from Liang (1997), tree length was 791, and the major lineages on the tree were supported by high bootstrap values that ranged from 73% to 100%.

From the phylogenetic consensus tree (Liang, 1997), the genus //Cynodon// is not seen to hold strong cladistic relationship. The two bootstrap values circled in red indicate weak support for //Cynodon// as a monophyletic group. Firstly, from the bootstrap value of 54%, the relationship between Group A (sister group of //Cynodon//) and Group B (group with //Cynodon//) is not well supported. Next, the phylogenetic relationship between genera //Eleusine// and //Cynodon// is also not robust (low bootstrap value of 67%), indicating that the genus //Cynodon// as a monophyletic group in the analysis is not well supported. However, from the tree, it can be seen that the phylogenetic relationship between genus //Cypholepis// and //Cynodon// is well supported as sister groups.

 A more recent publication by Liu et al. (2007) would further study the phylogenetic relationship for selected genera (in both Group A and B labelled in Figure 22) collectively termed as the 'finger millet clade'.  __**Position in the consensus tree of the 'finger millet clade'**__ As the Bermuda grass inflorescence resembles fingers on a hand, they are the members of the 'finger millet clade' (subtribe Chloridineae). The finger millet clade is found to be monophyletic in both morphological and molecular studies. Support for monophyly of the clade through morphology was based on cladistic analysis, and molecular evidence was based on the reconstruction of phylogeny using matK genes.

The phylogenetic tree generated by Liu et al. (2007) included species which similar looking inflorescence to the Bermuda grass such as the goosegrass (Figure 24) which can be differentiated by its spikes which sometimes do not grow from the stem apex.

By using the inflorescence, spikes and florets as the main characters, Liu //et al//. (2007) conducted a study investigating the developmental changes leading to the diversity of mature inflorescence in the finger millet clade to better understand the nature of digitate branching. The authors extracted DNA (non-coding chloroplast markers //trnL// intron and the //rps16// intron) from samples from the genera //Cynodon, Chloris, Eleusine, Dactyloctenium, and Microchloa// [35]. From this study, we can see the relationship of //Cynodon dactylon// with the other finger millet genera from a maximum parsimony tree (Figure 25).

From the results in Liu //et al.// (2007) parsimonious tree, almost all nodes showed 100 for bootstrap values, indicating that the cladistic relationship on the tree is robust. //Cynodon dactylon// is also supported (with bootstrap value of 100) to be monophyletic. In addition, similar to Figure 22, //Cynodon// is also shown to be sister group with the genus //Eleusine// although the bootstrap values for the node (branching to //Cynodon// and //Eleusine//) is not shown, suggesting that this node could be weakly supported (similar to the previous tree in Figure 22. However, this result suggests that //Cynodon// and //Eleusine// share a relationship closer to each other as compared a relationship shared by //Cynodon// and the remaining genera. This could indicate that //Cynodon// is phylogenetically more closely linked to //Eleusine// and that inflorescence structure could have been a more recent evolution.

Extra tips: How to grow Bermuda grass
As this is an invasive species in many countries, its growth can potentially devastate surrounding ecosystems. Do be mindful of where you plant these seeds (this grass is mostly used as turf grasses). Listed below are some basic criteria for growing Bermuda grass from seeds :

**__Seed production__** Occurs when temperatures are constantly above 18°C.

__**Optimal conditions for germination**__ Occurs when temperatures are from 24°C to 27°C, soil pH around 6.0 (apply fertiliser and lime as needed).

__**Best sites**__ __**Soil Coverage**__ Not more than 0.6cm of soil covering seeds at surface, but around 0.3cm of soil cover is considered ideal for good germination.
 * Full sun.
 * Well-drained, loosened soil (of about 15cm deep).
 * No addition of herbicides or weed and feeds for 10-14 weeks before and 10-14 weeks after seeding date.

__**Moisture**__ Seedbed must be kept moist, especially around the seed for 1-3 weeks.

Under good environmental conditions, germination would begin within 7-10 days from seeding and grass coverage on the grown area can be obtained 6-10 weeks after seeding.

Again, as the Bermuda grass is an invasive species in Singapore and other countries, growing discretion is advised in these regions. Other turf grasses can be grown in its stead to curb the invasive spread of the Bermuda grass in these regions.

Extra tips: How to get rid of Bermuda grass
Controlling the growth of Bermuda grass is important if the grass is growing as a weed in undesired places. Listed below are some means of controlling the growth of the Bermuda grass :

__**Shading**__ As Bermuda grass is a full sun plant, shading will weaken it.

__**Watering pattern**__ As shallow and frequent watering helps promote the growth of Bermuda grass, watering deeply and infrequently may help curb it.

__**Chemical means**__ Treating the grass with herbicides over many rounds of treatment can eliminate the grass. Treatment is best done when the grass is active (at higher temperatures) and this would be more effective than treating them when inactive. However, more potent chemicals can potentially kill surrounding vegetation.

Digging up all the rhizomes and stolons is also an important factor for eliminating this grass.

Glossary
** Awnless ** - A slender bristle, especially one at the tip of a glume or lemma in a grass spikelet. ** C4 ** - C4 photosynthesis that makes a four-carbon sugar during the Calvin cycle instead of two three-carbon sugars as in C3 plants. ** Culm ** - T he hollow stem of a grass or cereal plant, especially that bearing the flower. ** Dormancy ** - A period in an organism's life cycle when growth, development, and (in animals) physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. ** Genotype ** - The genetic constitution of an individual organism. ** Glumes ** - Each of two membranous bracts surrounding the spikelet of a grass (e.g. forming the husk of a cereal grain) ** Internode ** - A part of a plant stem between two of the nodes from which leaves emerge. ** Irradiance ** - The level of light intensity. ** Ligules ** - A narrow strap-shaped part of a plant, especially a membranous scale on the inner side of the leaf sheath at its junction with the blade in most grasses and sedges. ** Node ** - The part of a plant stem from which one or more leaves emerge, often forming a slight swelling. ** Perennial grass ** - A grass that lives for more than two years. ** Photoperiod ** - The period of time each day during which an organism receives illumination; day length. ** Photosensitizing ** - Causes extreme sensitivity to ultraviolet (UV) rays from the sun and other light sources. ** Rhizome ** - A continuously growing horizontal __underground stem__ which puts out lateral shoots and adventitious roots at intervals. ** Rhizomatous ** - Having rhizomes ** Ribbing ** - A rib-like structure or pattern. ** Runners ** - Also called stolons ** Stolon ** - Also called runners, stolons are __stems which grow at the soil surface__ or just below ground that form adventitious roots at the nodes, and new plants from the buds. ** Stoloniferous ** - Having stolons

Page by: Go Si Hui Disclaimer: I only own the images labelled with "own photo". Other images are used with permission, or under Fair Use and Creative Commons as stated in the figure captions. Please contact me at sihui_go@u.nus.edu for any clarifications. All images used are solely for academic purposes only. Last updated: 22/11/2016