Morphology and Physiological Characteristics of Invasive

Eupatorium odoratum in Laos and China

Yuxin Nian

, Rong Xiang

, Tianyu Pan

, Inxiem Vorlasane

, Qing Ji

and Ruifang Wang

Pu’er University, Pu’er, Yunnan Province 665000, China

Keywords: Eupatorium odoratum, Biological Invasion, Genetic Character.

Abstract: Eupatorium odoratum is a global invasive species that poses great harm to biodiversity. This study explores

the morphological and physiological genetic leaf changes in China and Laos. The results showed that the leaf

length / width ratio between China and Laos was significantly different, while the chlorophyll content, average

leaf area and specific leaf area were not different, indicating that some genetic changes have been emerged in

the invasion from Laos to China. Further comparison of the morphology, physiological and genetic

characteristics in Laos and China is conducive to further analysis of the genetic evolution for E. odoratum,

which puts forward suggestions on the future research direction and provide theoretical basis for the

prevention and control of E. odoratum.

1 INTRODUCTION

Biological invasion refers to the phenomenon that a

certain creature is naturally introduced from other

places or artificially introduced into a wild state, and

causes certain harm to the local ecosystem. E.

odoratum is mainly distributed in subtropical and

tropical areas, and China is mainly distributed in the

southern areas. E. odoratum, a weed with malignant

invasive properties because of its very tenacious

reproductive properties, asexual or sexual

reproduction belongs to the Zeeland family of

Chrysanthemum aceae.

The origin of E. odoratum is

South America, where there are a large number of

insects with E. odoratum as food, and pathogenic

infection, making E. odoratum does not have a large

number of growth. However, when E. odoratum was

introduced into other new areas, because of its

physiological characteristics, such as in patches of

single community, generally exclude other plants to

death by blocking the sun. Therefore,

the invasion of

E. odoratum has great harm to the local plants and

crops in the invaded sites.

https://orcid.org/0000-0002-3536-6518

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https://orcid.org/0000-0002-3514-4085

Further researches comprehensively analyzed the

invasion mechanism of E. odoratum through its

distribution characteristics, spatial pattern, age

structure, physiological characteristics, reproductive

characteristics and life history characteristics and

found that: First, grass has wide ecological scale and

low requirements on water and nutrient conditions.

As long as the areas where human activities have

destroyed, it can also grow. Second, it can occupy

many habitats. In different airport distribution areas,

regardless of the habitat conditions, it can become the

dominant community of the local environment. And

that can cause harm to the local biological

environment and affect the growth of other organisms

1.1 Hazard of E. odoratum

The first is to erode the grass, E. odoratum

reproduction capacity is very strong, can be a lot of

asexual reproduction, at the same time the seeds are

small, breeding speed is fast. In the grassland area, as

long as the plane grass occupies the grassland, it will

compete with the grass plants for sunshine, water,

fertilizer, and can produce chemical substances,

https://orcid.org/0000-0002-3852-4446

https://orcid.org/0000-0002-4126-7137

https://orcid.org/0000-0003-4715-6240

Nian, Y., Xiang, R., Pan, T., Vorlasane, I., Ji, Q. and Wang, R.

Morphology and Physiological Characteristics of Invasive Eupatorium odoratum in Laos and China.

DOI: 10.5220/0011185200003444

In Proceedings of the 2nd Conference on Artiﬁcial Intelligence and Healthcare (CAIH 2021), pages 75-79

ISBN: 978-989-758-594-4

inhibit the growth of neighboring plants. When high

at 15 cm or higher, it can significantly affect the

growth of other herbs, and reject insects, and

seriously damage ecological stability. In addition, the

E. odoratum leaves are lush. When taking root and

sprouting, the lush leaves as tools to cover the grass

and seize resources, resulting in the original growing

grass malnutrition, thus occupying the whole

grassland. The second affects crop production, which

when 120 days after airgrass invasion, will cause

severe land degradation. According to incomplete

statistics, E. odoratum generally results in grain

reduction by 3 percent, up to 11 percent. This means

that farmers fail to harvest more than 20% of grain

every year. At the same time to prevent and eradicate

E. odoratum, then each farmer should invest more

when planting, which leads to a rise in food prices,

which leads to the instability of the whole economy,

and the economic market will fluctuate.

Finally, it is poisonous in nature, and the seeds

and pollen can cause asthma in horse animals, and

even cause necrosis and death of livestock tissues.

Leaves are poisonous, contain coumarin, can cause

human allergic diseases, used to gaskets or field

compost will cause livestock hoof and fork, human

hands, feet suffer from skin inflammation, so it is also

known as rotten foot grass by the masses. Livestock

accidentally eat a certain amount of poisoning,

walking shaking, foaming at the mouth, seriously fell

to the ground limbs spasm, and finally heart failure.

Wipe the skin with leaves will cause redness and

swelling, foaming, mistakenly eating tender leaves

can cause dizziness, vomiting, but also can cause

livestock and fish poisoning, under serious

circumstances can lead to its heart failure and death.

1.2 The Spread of E. odoratum

There has a wide range of transmission routes. In

addition to wind and water media, it can also be

spread through human and animal activities. If the

airgrass from maturing, it can reduce its spread. Grass

cutting combined with tree planting to control is a

better method, by significantly reducing the number

of plane grass heads and reducing its seed production;

on the other hand, plane grass is shaded by growing

alternative plants, thus long-term control. In reducing

the transmission route of grass, but also actively

prevention and control. At present, the means of

prevention and control are physical control, chemical

control, biological control and comprehensive

prevention and control. However, the existing

prevention and control methods have their own

advantages and disadvantages in the use of the real

eradication of all aspects of the need to strengthen the

research.

1.3 Prevention and Control of

E. odoratum

Mechanical prevention and control is a universal

control method around the world, mainly refers to

manual cutting, but this method can not completely

eliminate E. odoratum. And this way for a small area

of E. odoratum invasion to add some later radical

cure, in order to have a certain effect. The approach

for extensive clearance is too costly. In addition, this

control method has another drawback, the leaves of

the plane grass are poisonous, and it is easily

poisoned in the process of manual cutting, leading to

a large area of skin infection. Alternative control is a

common way of biological control, but we do not

know what to happen to natural enemies. Because the

introduction of insects will have unknown effects on

both the environment and people. Therefore, the

biological replacement of this biological control

becomes a new means. There is a red gray leaf tree in

Sri Lanka similar to E. odoratum, both use cover

techniques to prevent other plants from absorbing

sunlight for growth, and this plant is of ecological

value and not demanding on soil, suitable for a variety

of climates and terrain. Its deep roots, very suitable

for wind and sand, not only can eradicate the invasion

of E. odoratum, but also can further change the

terrain, it can be said to kill two birds with one stone.

From the perspective of biological control,

chemical control, artificial control, farming, etc, each

kind of control has its own advantages and

disadvantages, in the actual process of control can use

of comprehensive control, combining several control

methods, complement each other, this way is very

popular abroad, but now our country or a single

means, no matter how there are disadvantages.

Therefore, the research focus of China should be on

the basis of understanding the biological

characteristics of E. odoratum and comprehensive

control of its harm

1.4 Genetics of E. odoratum

There are two E. odoratum with distinct

morphological differences in the invasion region

distribution. One occurs in West Africa, Central

Africa, Asia, Western Pacific and Oceania islands,

known as the Asian West African Biotype

(Asian/West Africa Biotype, AWAB); the other in

South Africa, known as the South African Biotype

(Southern African Biotype, SAB). The community

CAIH 2021 - Conference on Artiﬁcial Intelligence and Healthcare

inheritance of grass into China has very low diversity,

using DNA fragments of chloroplasts and ITS

(Internal transcribed spacers) and other DNA

analysis, grass in many countries in Asia are

haplotype and low genetic diversity, and relatively

low, all genetic diversity is 0.0406, Shannon index is

0.0623, so Feng Yulong guess that the grass has a

foundation role in entering China. E. odoratum land

is produced in America and invaded China through

Southeast Asia. In order to reveal the genetic

variation of E. odoratum through Laos and China,

this study compared the physiological and ecological

characteristics of E. odoratum population in similar

environments to reveal the strong invasion

mechanism of E. odoratum.

2 MATERIALS AND METHODS

2.1 Materials

The subjects of this study were E. odoratum in China

and E. odoratum in Laos respectively. 3m x3m

samples are selected in China and Laos, each divided

into 9 samples of 1m x 1m. Two sample samples were

randomly selected from 9 sample samples. Four E.

odoratum were randomly selected in each sample

square, and each plant removed the immature leaves

from top to bottom and collected 10 grow well leaves.

E. odoratum leaves in China and Laos are collected

in the same way back to the laboratory for processing.

2.2 Chlorophyll Concentration.

Take fresh leaves, cut off the thick leaf veins into

fragments, weigh 0.5g to the bowl and then added

pure acetone 3ml, a little calcium carbonate and

quartz sand, grind into a slurry, add 80% (volume

ratio) acetone 5ml, to hook the slurry to human

centrifuge tube, 4000 r/min centrifugal 10 min

abandoned precipitation, upper clearance with 80%

acetone to determine the capacity to 10 ml. The

pigment extract was 0.5 ml, plus 80% acetone 4 ml

and diluted into the cup, with 80% acetone, the

absorption values at 663 nm, 645 nm were measured

respectively. The concentrations of chlorophyll a and

b and total chlorophyll (mg/L) were calculated.

2.3 Leaf Length-width Ratio and

Specific Leaf Area (SLA)

10 aircraft blades from Laos and Pu'er were used, the

length of the longest and width of each blade was

measured with straight ruler, and the length and width

ratio was calculated by length / width. The specific

leaf area (specific leaf area, SLA) is the ratio of the

area of the leaf to its dry weight.

3 RESULTS AND ANALYSIS

3.1 Botany Characteristics of Laos and

China

E. odoratum growing in Laos is generally up to 3-7

m. Leaves are born out of the opposite phases, seed

shape similar to triangle, the front end gradually

small, coarse serrated edges, some like Cang ears,

with obvious three veins, rough sides, soft and

reddish brown gland points, crushed with pungent

smell; umbrella room head flower order; total bud

cylindrical, 1cm, total bracts 3-4 layers. Corolla

tubular, pale yellow, and stigma pink. Slender fruit

narrow linear, angular, 5 mm, long edges with short

hard hair; crown hair white, with brown hair.

Figure 1: Morphology of Laos (left) and Chinese E.

odoratum (right).

Most of the E. odoratum growing in China are

perennial herbs, with strong roots and walking

horizontally. The stem is erect, 1-3 meters tall, white

with fine stripes; branches, often opposite, horizontal

shot, straight angles to the main stem, and rarely

sharp angles with the main stem; all the branches are

thick yellow hairy or soft. Leaves are opposite, ovate,

triangular or ovate triangular, and the leaves in the

lower inflorescence are small and often fully related.

Most or few inflorescence row into compound

umbrella chamber or umbrella chamber at the top or

Morphology and Physiological Characteristics of Invasive Eupatorium odoratum in Laos and China

end of the stem or branches, inflorescence stem thick,

densely dense short soft hair, total bud cylindrical,

total bracts 3-4 layers, tile-covered arrangement,

outer bracts egg shape, wheat yellow pole. Flowers

are white or pink. Thin fruit is black-brown, 4 mm

long, 5 angular, glandless dots along which sparse

white stick pressed short pubhairs. Flower and fruit

period is April-December.

3.2 Chlorophyll, Leaf Length / Width

Ratio, SLA and Leaf Area

Figure 2: Chlorophyll content in leaves.

Figure 3: Ratio of leaf length to width.

Figure 4: Comparison of leaf area.

Figure 5: Comparison of average leaf area.

Poor leaf chlorophyll, leaf area and SLA differences

in China and Laos (p> 0.05). The leaf length / width

ratio were significant between China and Laos.

4 CONCLUSIONS

Through Laos and China plane of botany

characteristics, chlorophyll content, leaf grass,

comparing the aspect ratio, leaf area index can be

obtained, in terms of morphological traits, Laos grass

and Chinese E. odoratum are similar in

morphological characteristics in most, but in some

aspects, such as height, leaf shape, design and color

of a certain difference. In terms of chlorophyll

content, the difference of chlorophyll content in c.

odorata leaves between the two countries was not

significant. In terms of leaf length-width ratio, there

was significant difference between the two countries.

There was no significant difference in leaf area

between the two countries. The results showed that E.

odoratum, as a natural plant, could grow and

reproduce normally in a variety of different natural

environments. However, by comparing the various

traits of E.odoratum under different growth

environments, we can know that the various traits are

generally the same, but there are certain differences

in some aspects.

From this study, we show that Lao and Chinese E.

odoratum are mostly similar in morphological

characteristics, but not significantly in some such as

leaf edge shape, color, chlorophyll content,while the

blade leaf length / width ratio ratio was significantly

different. Analyzing the reasons, the variability in

traits exhibited by uniform species growing across

environments is the result of directional selection by

the external environment for the undirected variants

occurring in the organism.

Due to the limited experimental conditions, there

were relatively few traits included in the study. The

CAIH 2021 - Conference on Artiﬁcial Intelligence and Healthcare

content of the elements inside the E. odoratum blade

and the internal organelle morphology can be

included in the study of invasive mechanism of E.

odoratum More characters are studied, the

conclusions of this research can be more convincing,

it can also lay the foundation for further research

projects on grass genestic changes.

ACKNOWLEDGEMENTS

This work was supported by the National Natural

Science Foundation of China (31660170), Yunnan

Fundamental Research Projects (202101AU070030)

and Outstanding Young Teacher program

(2020GGJS006).

REFERENCES

Airgrass invasive and origin populations competing with

both native proximate species [D]. University of

Chinese Academy of Sciences, Chinese Academy of

Sciences, 2011.

Cao Honglin. Distribution and hazards of alien aircraft

grasses in Guangdong [J]. Guangdong Forestry

Technology, 2004,20 (20): 57-59.

Feng Yulong. Chlorophyll fluorescence properties and

photosynthetic pigment content of violet eland and

aircraft grass in different photostrong environments

[A]. The Chinese Society of Plant Physiology (The

Chinese Society for Plant Physiology). Summary of

academic papers at the National Annual Conference of

the 40th Anniversary of China Society of Plant

Physiology [C].Chinese Society of Plant Physiology

(The Chinese Society for Plant Physiology): Chinese

Society of Plant Physiology, 2003:1.

foreign invasive plant aircraft grasses [J]. China Agronomic

Bulletin, 2009,25 (9): 236-243.

Li Zhenyu, Xie Yan.Chinese alien invasion species [M].

Beijing: China Forestry Press, 2002,165.

Liu Jinhai, Huang Bizhi, Luo Fucheng. Introduction to

aircraft plant hazards and control measures [J]. Grass

Industry Science, 2006 (10): 73-77.

National Ming, Zhang Jiaen, Xu Huatian, et al.Biological

characteristics and control strategy of

Pan Yumei, Tang Saichun, Cen Yanxi, etc.Study on

Chemical Control in Karst Areas [J].China karst,

2011,30 (1): 53-58.

Tang Saichun, Lv Shihong, Pan Yumei, etc.Control effect

of grass mowing combined with tree planting method

in karst area, Guangxi [J] Application Ecology,

2011,22 (7): 1944-1948.

Zhang Baocheng, Wang Ping, Venus. Ornamental plants

with biological invasion [J]. Northern gardening, 2018

(5): 178-183.

Zhang Jianhua, Fan Zhiwei, Shen Yide, et al.

Characteristics and control measures of exotic weeds

[J]. Agricultural Research and Application, 2008 (3):

26-28.

Zhang Zhiying, Wei Yi, He Dayu.Preliminary Study of the

Biological Characteristics of Zeland solid fly [J].

Biocontrol notification, 1988,4 (1): 10-13.

Morphology and Physiological Characteristics of Invasive Eupatorium odoratum in Laos and China