Top 20 Most Common Weeds in Tonga

Tonga's warm, tropical climate provides an ideal environment for various garden weeds to flourish. Among the invasive species, Johnson grass, Mexican fireplant, and Chamber bitter are notably pervasive, often outcompeting native flora. These weeds present continual challenges for local gardeners, necessitating regular management efforts to curtail their spread and mitigate their impact on agricultural and natural landscapes.

Most Common Weeds

1. Johnson grass

Experts consider johnson grass (Sorghum halepense) to be one of the ten worst weeds in the world. If frost or heat causes the plant to wilt, it can produce enough hydrogen cyanide to kill livestock. It grows at such a prodigious rate, it can choke out other crops. It’s named after Colonel William Johnson, an Alabama plantation owner who sowed lots of its seed around 1840.

Growth Rate:

Rapid

2. Mexican fireplant

Mexican fireplant is native to tropical America, but it has been naturalized in other tropical and subtropical regions in the world. *Euphorbia heterophylla* is a poisonous plant to humans and livestock. It contains a toxic milky sap which can cause strong skin irritation.

3. Pepper elder

Pepper elder (Peperomia pellucida) is a perennial flowering plant that blooms all year. The entire pepper elder plant is edible and can be eaten raw or cooked.

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4. Chamber bitter

Chamber bitter is blooms in summer. Its striking branched leaf pattern makes it an attractive ornamental, but it is a weedy plant that takes careful management to stop its seeds from spreading to unwanted areas. It is considered invasive in the southern United States.

Growth Rate:

Moderate

5. Curlytop Knotweed

Curlytop Knotweed is an annual herb that grows 20 to 79 cm tall. It features purplish stems that bulge at the joints. Flowers bloom in mid to late summer and are tiny and pink. Its fruit is a rounded, flat nut.

6. Artillery plant

The artillery plant is often utilized as a groundcover or an ornamental in many landscapes. It's commonly named the "artillery plant" because the males generally produce pollen in an explosive way. It grows best in a humid environment in partial shade or indirect sunlight. It's a particularly popular plant in indoor rock gardens.

7. Creeping woodsorrel

Creeping woodsorrel (Oxalis corniculata) is a flowering herb which grows aggressively. The leaves have a lemony flavor and are often made into tea that's rich in vitamin C. However, if ingested in large amounts the oxalic acid for which the genus is named can begin to block the body's calcium absorption.

8. Three-lobed false mallow

Three-lobed false mallow (Malvastrum coromandelianum) is an annual and perennial herbaceous shrub native to North America and South America. This plant has been introduced to other areas of the world and is commonly found in Australia, Asia, and Africa.

9. Straggler daisy

The straggler daisy is a low-growing ground cover plant that tolerates shade and can withstand moderate foot traffic. The straggler daisy blooms for the entire spring, summer, and well into fall. In frost-free areas, year-round blooming is possible and the flowers of this plant are a sunny yellow color.

10. Arrowleaf sida

Arrowleaf sida (Sida rhombifolia) is a perennial plant with delicate yellow blooms on stiff, almost woody stems. The stems are used to make brooms, giving it the common name "broom jute." It is also used to make cord and twine.

11. Water hyacinth

Water hyacinth (Eichhornia crassipes) is a fast-growing flowering plant species with ovular, waxy leaves. Water hyacinth is listed as a federal noxious weed in the United States. This species is invasive to ponds, lakes, rivers and other wetland habitats. It forms dense, floating mats of vegetation that restricts light to underwater environments.

Growth Rate:

Rapid

12. Asthma-plant

Asthma-plant (Euphorbia hirta) is a ground-hugging spurge weed whose branches can grow to 61 cm long. It blooms from summer through early fall, dying off after the first frost. A milky sap will seep from broken stems or leaves. It can be a nuisance weed that reproduces rapidly.

Growth Rate:

Rapid

13. Cutleaf groundcherry

Physalis angulata is an annual plant belonging to the nightshade family Solanaceae. It has dark green leaves that are roughly oval, and often have tooth shapes around the edge. The flowers are a pale yellow and the yellow-orange fruits are wrapped inside a balloon-like calyx, which is toxic and should not be eaten.

14. American black nightshade

American black nightshade (*Solanum americanum*) is a flowering herb with unknown native origins, and it is poisonous. Its berries should not be consumed, as berry consumption has resulted in death in children.

15. Pigeonberry

The pigeonberry is a vine-like herb that can reach heights of 40 to 200 cm. It produces a bright red berry as a fruit that is tested to be safe to consume. The juice made from these berries was once used as a dye and ink.

16. Goosegrass

When there is a famine or a lack of food, the seeds of goosegrass are eaten. This agricultural weed is utilized for cultivated crops, animal feed, and golf courses. It is classified as an environmental weed in various nations. Some Asian countries employ parts of this plant as herbal medicine.

Growth Rate:

Rapid

17. Dallis grass

Dallis grass (Paspalum dilatatum) is a grass that could serve as a food source for many birds - particularly the long-tailed widowbird. On the stalks grow prodigious numbers of seeds, which enable its fast spread. Dallis grass is considered an invasive species in many places outside its home range. Once established, it is very hard to eradicate.

Growth Rate:

Moderate

18. Common purslane

Portulaca oleracea, colloquially known as common purslane, is an annual succulent species with reddish stems and tiny yellow, five-petal flowers. It is used for culinary purposes in various parts of the world, most often raw, in salads. Common purslane is also a good companion plant for crops that thrive in moist soils.

Growth Rate:

Rapid

19. Graceful spurge

Graceful spurge (Euphorbia hypericifolia) is a perennial flowering bush that blooms all year round. This species grows best in full sunlight or partial shade. Graceful spurge is resistant to rabbits and deer due to its toxic sap. This species is often cultivated as an ornamental plant and grown in containers, hanging baskets and gardens. Gardeners should wear gloves when handling graceful spurge due to its toxic sap.

Growth Rate:

Moderate

20. Pink woodsorrel

Pink woodsorrel (Oxalis debilis) is a flowering herb that can now be found on every inhabited continent. All the parts of pink woodsorrel are edible, but only in small amounts due to the presence of oxalic acid. The flavor is zesty and similar to lemon. This species can become a weed if not adequately controlled.

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As Spring awakens in Tonga, the environment transforms, offering a canvas for local flora to flaunt their colors. Flowers like , , and emerge, heralding the season's arrival. These blooms not only add vibrancy to the landscape but often carry deep cultural symbolism and are integral to local festivities and traditions, reflecting the island's rich botanical heritage.

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Most Common Trees

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Most Common Plants

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