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Abstract An investigation was carried out in wharves， inspection yards， processing plants in Beilun Port and the surrounding areas. Five kinds of exotic harmful weeds were discovered and collected， and they were described and analyzed.
Key words Beilun Port; Exotic harmful weeds; Ecological security
Beilun Port is one of the designated ports for grain entering China， and total amount of the imported grain per year is more than 1.5 million t. In a port， sealand logistics are frequent， and a large amount of cargo trade greatly increases the possibility of invasion of alien species and even quarantine pests. The invasion of alien species will pose a serious threat to local ecological environment construction， social economy and safety and health of people and animals. Beilun EntryExit Inspection and Quarantine Bureau has repeatedly intercepted a variety of quarantine harmful weed seeds in grain entering China， and there is a high risk of colonization of exotic harmful weeds in Beilun Port. To this end， all important wharves and processing plants in the port have been monitored every year to maintain ecological security. In recent years， several exotic harmful weeds have been discovered and collected during the monitoring and investigation of exotic harmful weeds in Beilun Port.
Investigation Scope and Method
The survey was mainly conducted in various wharves， yards and processing plants importing grain in Beilun Port. Onthespot investigation was carried out in open space within 1 km in each survey area. The species of found weeds were visually surveyed， and highresolution photos were collected with a digital camera. Specimens were collected and made if necessary.
Investigation results
Amaranthus palmeri
A. palmeri， an annual herb， belongs to Subgen Acnida L.， Amaranthus and is native to the southwestern United States. It is 2 m in height and is dioecious. Its stems are erect and stout and have branches. Its leaves are ovate or rhomboid ovate. The panicles are at the top of a plant， and the upper part bends or is cernuous. The inflorescence of a male flower is about 5 cm in length and often has no leaves. The inflorescence of a female flower is 1-2 cm in length， and the top inflorescence often have leaves. The bract of a male flower is long and has a very fine midrib. The bract of a female flower has unobvious keel， and its top becomes pointed gradually. Each male flower has five perianths that become pointed gradually and have a significantly protruding midrib. There are five stamens. Each female flower has five perianths that slightly extend outwards and have the same length. The outermost one has a broadleaved midrib and is oblanceolate; it is 3-4 mm in length， and its tip is very pointed. The other perianths look like a spoon， and the tip is truncated or slightly concave， sometimes looking like a grinding tooth. The utricle does not have longitudinal edges and is obovate or nearly spherical. Its wall is thin， nearly smooth or irregularly shrunken， no cracking， irregular cracking or circumferential cracking. The seeds are nearly round or broadly ovate， and the annular edges are wide and thick， dark reddish brown or brown; the hilum is not prominent and shiny[1-5]（Fig. 1 and Fig. 2）. Amaranthus spinosus L.
A. spinosus L.， an annual herb， belongs to Amaranthaceae and is native to the tropical America. The adult plants are 30-100 cm in height. The stems are erect and have many branches. They are green or reddish， and the lower part is pubescent， while the upper part is glabrous or slightly pubescent. The leaves are rhomboid ovate or ovate lanceolate and are 3-12 cm in length and 1.0-5.5 cm in width. The apex often has fine thorns， and the base is cuneate. The leaf edge is flat， and the leaves have a petiole and two thorns on both sides. The flowers are unisexual or polygamous. The female flowers cluster in the leaf axils， while the male flowers form a terminal panicle， and it is 3-25 cm in length. Part of bracts become sharp spines， while a part of bracts is narrowly lanceolate. The perianth is green， and its apex is acute， while its margin is transparent. There are five stamens， and the filaments and perianths are slightly equal in length or shorter. Each female flower has three or two stigmas sometimes. The utricles are oblong， and the cover is cracked and enclosed in a persistent perianth. The seeds are obovate or round， slightly flat and convex lensshaped. The circumference is banded with fine grain stripes; the surface is black and shiny; the hilum is located at the base[3-5]（Fig. 3）.
Lactuca serriola L.
L. serriola L.， an annual herb， belongs to Lactuca， Compositae and is native to Europe， Central Asia. It is about 60-250 cm in height. The stems are erect and have milk. The leaves are alternate， and the middle and lower leaves are narrowly obovate or oblong. They are often pinnate and crack deeply or backward pinnate and lobed slightly， cleft or lobed deeply. They are 3-25 cm in length and 1-7 cm in width. There is no petiole， and the base is arrowshaped. The terminal leaf is ovate lanceolate or lanceolate. The leaf edge is flat or has only sparse toothlike thorns. Many flower heads are arranged in a sparsely large conical shape at the top of a stem. Each flower head is composed of 7-15 ligulate flowers. The corolla is yellowish and becomes bluepurple after being dry. Each flower head produces 6-30 achenes. The achenes are obovate and often curve to one side. They are graybrown， lacklustre and flat on both sides; the umbilicus is located at the base of the fruit， and there is white protrusion around it， while the central part is concave; the fruit contains a seed with the same shape as the fruit， and there is no endosperm[6-7]（Fig. 4）. Sorghum halepense （L.） Pers.
S. halepense （L.） Pers.， a gramineous herb， is native to Mediterranean regions. It has underground creeping rhizome that is solid and has nodes. The plants are 100-200 cm in height. The stems are erect. The ligules are membranous and have hairs on the edge. The leaves are stripshaped lanceolate. The panicles are scattered， and the branches are verticillate. The cobs and spikelets are slender， with cilia on both sides. The spikelets are twinborn， of which one has a petiole and the other one is sessile. The three spikelets at the top of a cob are symbiotic. The sessile spikelet is bisexual， ovate lanceolate and tawny or purple brown. It is 4.8-5.2 mm in length and 2.6-3.0 mm in width. The cob internodes are easy to fall off; the glume is leathery， shiny， with cilia at the base and edges. The caryopsis is brown， obovate and 2.6-3.2 mm in length， with a rounded tip and a persistent pattern[3，5]（Fig. 5）.
Ambrosia trifida L.
A. trifida L.， an annual herb， belongs to Ambrosia L.， Compositae and is native to North America. The stems are 50-120 cm in height and have branches on the upper part. The leaves are opposite and petiolate. The lower leaves have 3-5 lobes and serration on the edge. The upper leaves have three lobes or sometimes are not lobed， and are broadly elliptical， oval or round， and sometimes lanceolate. The flower heads are unisexual; the male inflorescences are born in the upper part and arranged in a long raceme. The involucre of male inflorescences is ringlike， and there are 7-12 bracts. The female inflorescences are sessile and born in leaf axils， and 1-3 female flowers grow intensively. The female inflorescences are large， and the involucre is closed， with a flower inside， while the receptacle is bare. The involucre is 6.0-12.0 mm in length and smooth on the surface. At the top， there is a conical long plaque with a length of 2.0-4.0 mm in the center， and there are 5-10 spinous protrusions around it， which are inclined upwards and extend along the surface of the involucre into longitudinal ribs. The involucre has one room where there is an achene. The achene is not cracked and obovate or long obovate， and its peel is thin. It is gray， brown or taupe， and its surface is smooth and slightly shiny. The achene contains one seed. The seed is obovate or long obovate， and there are white or slightly darker longitudinal veins on the surface; there is no endosperm[3-5]（Fig. 6）.
Conclusions and Discussion Some exotic harmful weeds were introduced unconsciously， but some were originally introduced as forage， feed， ornamental plants， etc. However， due to the lack of restriction mechanisms， they have been spread and caused a series of harm to the environment.
Among exotic weeds， most weeds belong to Compositae and are scattered. For instance， L. serriola L. is distributed in many surveyed areas. The weeds belonging to Amaranthaceae are mostly distributed in the grain processing plants and warehouses and on both sides of the transport roads.
A. palmeri is a malignant foreign harmful weed that has been paid close attention in recent years. Its seeds are small and adaptable and have large yield. It is easy to form a dominant population. Once it is built， it can spread rapidly and multiply， thereby forming a hazard and threatening local biodiversity. The plants are enriched with nitrite， and animals can suffer from poisoning after feeding on excessive amounts of the plants.
Most foreign weeds will cause local crops to be reduced in yield through competition， and some will be toxic to people and animals. For example， A. spinosus L. harms farmland and orchards， and consumes soil fertility. The mature plants have spines， thus it is difficult to remove them， and they can harm people and animals. A. trifida L. inhibits crop growth and affects crop yield. Its spread pollen causes human allergies， produces asthma， and can cause death in severe cases. The whole plant of L. serriola L. is poisonous. S. halepense （L.） Pers. will also hybridize with other plants of the same genus.
Every year， China invests a large amount of manpower， material resources and financial resources due to the invasion of exotic plants. Phytosanitary workers should update the list of official pests timely， continue to strengthen epidemic tracking， and monitor the invasion， spread and prevention of exotic pests in real time.
References
[1]LI ZY. Amaranthus palmeri――A newly naturalized species in China[J]. Chinese Bulletin of Botany， 2003， 20（6）： 734-735. （in Chinese）.
[2]XU H， SONG Y， FAN XH， et al. Invasion risk and suitability analysis of three kinds of Acnida weeds （Subgen. Acnida L.） in China[J]. Plant Quarantine， 2013， 27（4）： 20-23. （in Chinese）.
[3]CHE JD. Color illustrated handbook of exotic weeds in China[M]. Beijing： Chemical Industry Press， 2010. （in Chinese）.
[4]FAN XH， SHAO XL， XU H， et al. Monitoring map of alien weeds in ports[M]. Beijing： China Science and Technology Press， 2016. （in Chinese）.
[5]LIANG DY， ZHANG Z. Identification atlas of weeds in Chinaюs agricultural areas[M]. Beijing： China Agricultural Science and Technology Press， 2014. （in Chinese）.
[6]LIANG ZW， TONG ML， GAO ZF， et al. Comparative study on morphological characteristics of Lactuca serriola and its close relative species[J]. Plant Quarantine， 2014， 28（4）：36-40. （in Chinese）.
[7]General Administration of Quality Supervision， Inspection and Quarantine of the People’s Republic of China. Quarantine identification of Lactuca serriola L. （SN/T 2339-2009）[S]. 2009. （in Chinese）.
Key words Beilun Port; Exotic harmful weeds; Ecological security
Beilun Port is one of the designated ports for grain entering China， and total amount of the imported grain per year is more than 1.5 million t. In a port， sealand logistics are frequent， and a large amount of cargo trade greatly increases the possibility of invasion of alien species and even quarantine pests. The invasion of alien species will pose a serious threat to local ecological environment construction， social economy and safety and health of people and animals. Beilun EntryExit Inspection and Quarantine Bureau has repeatedly intercepted a variety of quarantine harmful weed seeds in grain entering China， and there is a high risk of colonization of exotic harmful weeds in Beilun Port. To this end， all important wharves and processing plants in the port have been monitored every year to maintain ecological security. In recent years， several exotic harmful weeds have been discovered and collected during the monitoring and investigation of exotic harmful weeds in Beilun Port.
Investigation Scope and Method
The survey was mainly conducted in various wharves， yards and processing plants importing grain in Beilun Port. Onthespot investigation was carried out in open space within 1 km in each survey area. The species of found weeds were visually surveyed， and highresolution photos were collected with a digital camera. Specimens were collected and made if necessary.
Investigation results
Amaranthus palmeri
A. palmeri， an annual herb， belongs to Subgen Acnida L.， Amaranthus and is native to the southwestern United States. It is 2 m in height and is dioecious. Its stems are erect and stout and have branches. Its leaves are ovate or rhomboid ovate. The panicles are at the top of a plant， and the upper part bends or is cernuous. The inflorescence of a male flower is about 5 cm in length and often has no leaves. The inflorescence of a female flower is 1-2 cm in length， and the top inflorescence often have leaves. The bract of a male flower is long and has a very fine midrib. The bract of a female flower has unobvious keel， and its top becomes pointed gradually. Each male flower has five perianths that become pointed gradually and have a significantly protruding midrib. There are five stamens. Each female flower has five perianths that slightly extend outwards and have the same length. The outermost one has a broadleaved midrib and is oblanceolate; it is 3-4 mm in length， and its tip is very pointed. The other perianths look like a spoon， and the tip is truncated or slightly concave， sometimes looking like a grinding tooth. The utricle does not have longitudinal edges and is obovate or nearly spherical. Its wall is thin， nearly smooth or irregularly shrunken， no cracking， irregular cracking or circumferential cracking. The seeds are nearly round or broadly ovate， and the annular edges are wide and thick， dark reddish brown or brown; the hilum is not prominent and shiny[1-5]（Fig. 1 and Fig. 2）. Amaranthus spinosus L.
A. spinosus L.， an annual herb， belongs to Amaranthaceae and is native to the tropical America. The adult plants are 30-100 cm in height. The stems are erect and have many branches. They are green or reddish， and the lower part is pubescent， while the upper part is glabrous or slightly pubescent. The leaves are rhomboid ovate or ovate lanceolate and are 3-12 cm in length and 1.0-5.5 cm in width. The apex often has fine thorns， and the base is cuneate. The leaf edge is flat， and the leaves have a petiole and two thorns on both sides. The flowers are unisexual or polygamous. The female flowers cluster in the leaf axils， while the male flowers form a terminal panicle， and it is 3-25 cm in length. Part of bracts become sharp spines， while a part of bracts is narrowly lanceolate. The perianth is green， and its apex is acute， while its margin is transparent. There are five stamens， and the filaments and perianths are slightly equal in length or shorter. Each female flower has three or two stigmas sometimes. The utricles are oblong， and the cover is cracked and enclosed in a persistent perianth. The seeds are obovate or round， slightly flat and convex lensshaped. The circumference is banded with fine grain stripes; the surface is black and shiny; the hilum is located at the base[3-5]（Fig. 3）.
Lactuca serriola L.
L. serriola L.， an annual herb， belongs to Lactuca， Compositae and is native to Europe， Central Asia. It is about 60-250 cm in height. The stems are erect and have milk. The leaves are alternate， and the middle and lower leaves are narrowly obovate or oblong. They are often pinnate and crack deeply or backward pinnate and lobed slightly， cleft or lobed deeply. They are 3-25 cm in length and 1-7 cm in width. There is no petiole， and the base is arrowshaped. The terminal leaf is ovate lanceolate or lanceolate. The leaf edge is flat or has only sparse toothlike thorns. Many flower heads are arranged in a sparsely large conical shape at the top of a stem. Each flower head is composed of 7-15 ligulate flowers. The corolla is yellowish and becomes bluepurple after being dry. Each flower head produces 6-30 achenes. The achenes are obovate and often curve to one side. They are graybrown， lacklustre and flat on both sides; the umbilicus is located at the base of the fruit， and there is white protrusion around it， while the central part is concave; the fruit contains a seed with the same shape as the fruit， and there is no endosperm[6-7]（Fig. 4）. Sorghum halepense （L.） Pers.
S. halepense （L.） Pers.， a gramineous herb， is native to Mediterranean regions. It has underground creeping rhizome that is solid and has nodes. The plants are 100-200 cm in height. The stems are erect. The ligules are membranous and have hairs on the edge. The leaves are stripshaped lanceolate. The panicles are scattered， and the branches are verticillate. The cobs and spikelets are slender， with cilia on both sides. The spikelets are twinborn， of which one has a petiole and the other one is sessile. The three spikelets at the top of a cob are symbiotic. The sessile spikelet is bisexual， ovate lanceolate and tawny or purple brown. It is 4.8-5.2 mm in length and 2.6-3.0 mm in width. The cob internodes are easy to fall off; the glume is leathery， shiny， with cilia at the base and edges. The caryopsis is brown， obovate and 2.6-3.2 mm in length， with a rounded tip and a persistent pattern[3，5]（Fig. 5）.
Ambrosia trifida L.
A. trifida L.， an annual herb， belongs to Ambrosia L.， Compositae and is native to North America. The stems are 50-120 cm in height and have branches on the upper part. The leaves are opposite and petiolate. The lower leaves have 3-5 lobes and serration on the edge. The upper leaves have three lobes or sometimes are not lobed， and are broadly elliptical， oval or round， and sometimes lanceolate. The flower heads are unisexual; the male inflorescences are born in the upper part and arranged in a long raceme. The involucre of male inflorescences is ringlike， and there are 7-12 bracts. The female inflorescences are sessile and born in leaf axils， and 1-3 female flowers grow intensively. The female inflorescences are large， and the involucre is closed， with a flower inside， while the receptacle is bare. The involucre is 6.0-12.0 mm in length and smooth on the surface. At the top， there is a conical long plaque with a length of 2.0-4.0 mm in the center， and there are 5-10 spinous protrusions around it， which are inclined upwards and extend along the surface of the involucre into longitudinal ribs. The involucre has one room where there is an achene. The achene is not cracked and obovate or long obovate， and its peel is thin. It is gray， brown or taupe， and its surface is smooth and slightly shiny. The achene contains one seed. The seed is obovate or long obovate， and there are white or slightly darker longitudinal veins on the surface; there is no endosperm[3-5]（Fig. 6）.
Conclusions and Discussion Some exotic harmful weeds were introduced unconsciously， but some were originally introduced as forage， feed， ornamental plants， etc. However， due to the lack of restriction mechanisms， they have been spread and caused a series of harm to the environment.
Among exotic weeds， most weeds belong to Compositae and are scattered. For instance， L. serriola L. is distributed in many surveyed areas. The weeds belonging to Amaranthaceae are mostly distributed in the grain processing plants and warehouses and on both sides of the transport roads.
A. palmeri is a malignant foreign harmful weed that has been paid close attention in recent years. Its seeds are small and adaptable and have large yield. It is easy to form a dominant population. Once it is built， it can spread rapidly and multiply， thereby forming a hazard and threatening local biodiversity. The plants are enriched with nitrite， and animals can suffer from poisoning after feeding on excessive amounts of the plants.
Most foreign weeds will cause local crops to be reduced in yield through competition， and some will be toxic to people and animals. For example， A. spinosus L. harms farmland and orchards， and consumes soil fertility. The mature plants have spines， thus it is difficult to remove them， and they can harm people and animals. A. trifida L. inhibits crop growth and affects crop yield. Its spread pollen causes human allergies， produces asthma， and can cause death in severe cases. The whole plant of L. serriola L. is poisonous. S. halepense （L.） Pers. will also hybridize with other plants of the same genus.
Every year， China invests a large amount of manpower， material resources and financial resources due to the invasion of exotic plants. Phytosanitary workers should update the list of official pests timely， continue to strengthen epidemic tracking， and monitor the invasion， spread and prevention of exotic pests in real time.
References
[1]LI ZY. Amaranthus palmeri――A newly naturalized species in China[J]. Chinese Bulletin of Botany， 2003， 20（6）： 734-735. （in Chinese）.
[2]XU H， SONG Y， FAN XH， et al. Invasion risk and suitability analysis of three kinds of Acnida weeds （Subgen. Acnida L.） in China[J]. Plant Quarantine， 2013， 27（4）： 20-23. （in Chinese）.
[3]CHE JD. Color illustrated handbook of exotic weeds in China[M]. Beijing： Chemical Industry Press， 2010. （in Chinese）.
[4]FAN XH， SHAO XL， XU H， et al. Monitoring map of alien weeds in ports[M]. Beijing： China Science and Technology Press， 2016. （in Chinese）.
[5]LIANG DY， ZHANG Z. Identification atlas of weeds in Chinaюs agricultural areas[M]. Beijing： China Agricultural Science and Technology Press， 2014. （in Chinese）.
[6]LIANG ZW， TONG ML， GAO ZF， et al. Comparative study on morphological characteristics of Lactuca serriola and its close relative species[J]. Plant Quarantine， 2014， 28（4）：36-40. （in Chinese）.
[7]General Administration of Quality Supervision， Inspection and Quarantine of the People’s Republic of China. Quarantine identification of Lactuca serriola L. （SN/T 2339-2009）[S]. 2009. （in Chinese）.