Top 10 most poisonous plants

1/Abrus precatorius(rosary pea)

Rosary pea has been widely used in Florida as an ornamental plant for many years. The native range of rosary pea is India and parts of Asia, where this plant is used for various purposes. The roots of this plant are used to induce abortion and relieve abdominal discomfort. The seeds of this plant are so uniform in size and weight that they are used as standards in weight measurement. The seeds can also be used to make jewelry. Interestingly, one of the most deadly plant toxins, abrin, is produced by rosary pea (Abrus precatorius). Studies have shown that as little as 0.00015% of toxin per body weight will cause fatality in humans (a single seed). Interestingly, birds appear to be unaffected by the deadly toxin as they have been shown to readily disperse rosary pea seed.Rosary pea is a small, high climbing vine with alternatelycompound leaves, 2-5 inches long, with 5 to 15 pairs of oblong leaflets. A key characteristic in identifying rosary pea is the lack of a terminal leaflet on the compound leaves. The flowers are small, pale, and violet to pink, clustered in leaf axils. The fruit is characteristic of a legume. The pod is oblong, flat and truncate shaped, roughly 1½ – 2 inches long. This seedpod curls back when it opens, revealing the seeds. The seeds are small, brilliant red with a black spot. These characteristics give the plant another common name of crab’s eyes.

2/Aconitum

Aconitum also has the common name Monkshood. The hooded blue flowers have quite a dramatic look, and do look like hoods when seen close-up.The stem is about 3 feet high, with dark green, glossy leaves, deeply divided in palmate manner and flowers in erect clusters of a dark blue colour. The shape of the flower is specially designed to attract and utilize bee visitors, especially the humble bee. The sepals are purple – purple being specially attractive to bees – and are fancifully shaped, one of them being in the form of a hood. The petals are only represented by the two very curious nectaries within the hood, somewhat in the form of a hammer; the stamens are numerous and lie depressed in a bunch at the mouth of the flower. They are pendulous at first, but rise in succession and place their anthers forward in such a way that a bee visiting the flower for nectar is dusted with the pollen, which he then carries to the next flower he visits and thereby fertilizes the undeveloped fruits, which are in a tuft in the centre of the stamens, each carpel containing a single seed.

The roots of Aconitum ferox supply the Nepalese poison called bikh, bish, or nabee. It contains large quantities of the alkaloid pseudaconitine, which is a deadly poison. Aconitum palmatum yields another of the bikh poisons. The root of Aconitum luridum, of the Himalaya, is said to be as poisonous as that of A. ferox or A. napellus.Several species of Aconitum have been used as arrow poisons. The Minaro in Ladakh use A. napellus on their arrows to hunt ibex, while the Ainu in Japan used a species of Aconitum to hunt bear.The Chinese also used Aconitum poisons both for hunting and for warfare.

3/Wisteria

Wisteria (also spelled Wistaria) is a genus of flowering plants in the pea family, Fabaceae, that includes ten species of woody climbing vines native to the eastern United States and to China, Korea, and Japan. Aquarists refer to the species Hygrophila difformis, in the family Acanthaceae, as Water Wisteria. Some species are popular ornamental plants, especially in China and Japan.Wisteria vines climb by twining their stems either clockwise or counter-clockwise round any available support. They can climb as high as 20 m above the ground and spread out 10 m laterally. The world’s largest known Wisteria vine is in Sierra Madre, California, measuring more than 1 acre (0.40 ha) in size and weighing 250 tons.Wisteria is part of the Leguminosae family, and contains the glycoside wistarin and another toxic component called lectin.  While the pods and seeds contain the majority of these toxins, all parts of this plant are considered to be poisonous. If ingested, wisteria can produce significant abdominal pain, vomiting, diarrhea, and potentially profound central nervous system depression. Ingestion of only one or two seeds can cause serious illness.  Based on this, you should not allow your dog to chew on this plant.

4/Cassava

Cassava (Manihot esculenta) is a short-lived perennial, 1 to 5 meters tall. The origin of cassava is in South America, presumably eastern Brazil. From stem cuttings, the plant produces 5 to 10 very fleshy adventitious roots up to 15 centimeters in diameter. Young roots may have 30-35% starch by weight but very little protein or fat. As many as 300 million people in the tropics consume cassava daily. After planting a stem cutting, the crop does not have to be tended, and the roots are harvested 6 to 8 months later before they become woody. Cassava has the greatest yield of starch per acre of any crop in the world–often exceeding 20 tons of roots per acre.Starch from cassava can be used for producing sugar, acetone, and alcohol. Some people believe that Brazil can produce 20% of the alcohol its needs for motor fuel from cassava.

The cells in cassava root contain highly poisonous cyanoglucoside. The latex contains enzymes which break down the poison, but the enzyme and the poison do not come into contact in the living plant. Processing cassava breaks down the cells, allowing the enzymes to reach the poisonous cyanoglucoside and convert it to hydrogen cyanide gas. The gas is given off, leaving the root safe to eat.

5/Phaseolus vulgaris

Phaseolus vulgaris, the common bean, is an herbaceous annual plant domesticated independently in ancient Mesoamerica and the Andes, and now grown worldwide for its edible bean, popular both dry and as a green bean.The common bean is the most important economic variety of the genus Phaseolus, and is grown in all parts of the world. It requires much warmth and sun. Cool weather and wind hamper the growth. Medium heavy or light soils are preferred.Common beans include the French or European beans that produce very narrow, sometimes pencil-thin, pods. Italians prefer the thicker, flatter Romano beans. Wax beans are long and narrow with yellow pods and a waxy appearance. Purple beans such as Royal Burgundy, add color to the garden but the pods change to green when boiled. They are produced both as ornamentals and as edible vegetables. Ornamental beans like scarlet runner beans produce striking, bright red blooms followed by beans that are edible while young. Blue hyacinth beans produce deep lilac-blue flowers which produce maroon bean pods. Ornamental beans are usually planted for their attractive flowers rather than for consumption. They grow quickly up to beautifully cover fences, trellises and arbors.

The toxic compound phytohaemagglutinin, a lectin, is present in many varieties of common bean but is especially concentrated in red kidney beans. Beans are high in purines, which are metabolized to uric acid. Uric acid is not itself considered a toxin, but it may promote the development or exacerbation ofgout. For this reason, persons with gout are often advised to limit their consumption of beans.Uric acid is also an important antioxidant in humans and, according to cohort studies, might be neuroprotective in cases of multiple sclerosis and Parkinson’s disease.

6/Lima bean

The lima bean, also known as the chad bean or butter bean, is a large disk-shaped bean used in succotash. Lima beans originated in Peru and have been grown there since 6000 B.C. The name comes from the capital city of Peru, Lima. Lima beans are almost always called “butter beans” in the southern part of the United States, even in markets and restaurants.Lima bean is a crop widely distributed in Mesoamerica and the Andes, where several human groups have used it as food resource since pre-Columbian times. In spite of that, scientists have yet to describe its evolutionary history.Fresh lima beans need to be shelled before they are eaten. Shelling can be a little tricky, especially with larger beans. Beans are easier to handle if they are tender and have full pods. One method used for larger beans is to simply cut open the pod with scissors and remove the beans by hand. Raw beans contain dangerous amounts of linamarin, a cyanogenic glucoside.

7/Rhubarb

Rhubarb is a group of plants that belong to the genus Rheum in the family Polygonaceae. They are herbaceous perennial plants growing from short, thick rhizomes. They have large leaves that are somewhat triangular-shaped with long fleshy petioles. They have small flowers grouped in large compound leafy greenish-white to rose-red inflorescences.

Rhubarb will grow and produce on most soils, but grows best in fertile, well-drained soils that have good organic matter content. Careful soil preparation will help rhubarb stay healthy and productive for many years. The planting area should be cleared of any weeds, especially tough, hard-to-control perennial weeds.Other considerations for a planting site for rhubarb include exposure and location. Earliness is favored by a southern exposure, free from shading trees or buildings. Since rhubarb is a perennial, it should be planted to one side or at the end of the garden so as not to interfere with planting and growing annual vegetables. The rhubarb plant has bold ornamental texture and size, and some gardeners find it suitable to include in a perennial flower border.

Rhubarb leaves contain poisonous substances, including oxalic acid which is a nephrotoxic and corrosive acid that is present in many plants. The LD₅₀ (median lethal dose) for pure oxalic acid in rats is about 375 mg/kg body weight,or about 25 grams for a 65 kg  human. While the oxalic acid content of rhubarb leaves can vary, a typical value is about 0.5%,so a rather unlikely 5 kg of the extremely sour leaves would have to be consumed to reach an LD of oxalic acid. Cooking the leaves with soda can make them more poisonous by producing soluble oxalates.However, the leaves are believed to also contain an additional, unidentified toxin,which might be an anthraquinone glycoside (also known as senna glycosides).

8/Adenium obesum

Adenium obesum is a species of flowering plant in the dogbane family, Apocynaceae, that is native to the Sahel regions, south of the Sahara (from Mauritania and Senegal to Sudan), and tropical and subtropical eastern and southern Africa and Arabia. Common names include Sabi Star, Kudu, and Desert-rose.The plant can be poisonous to people and pets so keep it out of their reach if you want to grow this plant indoors.

Desert Rose or Adenium Obesum grows as tall as 1 to 3 meters in height. It produces green, leathery leaves that grow near the tips of branches. Adenium blooms in late spring and sometimes in mid fall. Flowers are red and pink with whitish shade and resemble the flowers of Frangipani.These days a number of hybrids are commercially grown and sold as houseplants. These hybrids bear spectacular flowers of many different shades. You can also find many different hybrids grafted on a single rootstock all producing flowers of different colors.

9/Aesculus hippocastanum

Aesculus hippocastanum is a deciduous Tree growing to 30 m (98ft) by 15 m (49ft) at a fast rate.It is hardy to zone 3 and is not frost tender. It is in flower in May, and the seeds ripen in September. The flowers are hermaphrodite (have both male and female organs) and are pollinated by Bees.The plant prefers light (sandy), medium (loamy) and heavy (clay) soils, requires well-drained soil and can grow in nutritionally poor soil.The plant prefers acid, neutral and basic (alkaline) soils..It can grow in semi-shade (light woodland) or no shade.It requires dry or moist soil.The plant can tolerates strong winds but not maritime exposure.It can tolerate atmospheric pollution.The nuts, especially those that are young and fresh, are slightly poisonous, containing alkaloid saponins and glucosides. Although not dangerous to touch, they cause sickness when eaten. Some mammals, notably deer, are able to break down the toxins and eat them safely. They are reputed to be good for horses with wind, but this is unproven and feeding them to horses is not advisable. The saponin aescin (a complex mixture of triterpene glycosides), however, has been used for health purposes (such as varicose veins, edema, sprains) and is available in food supplements, as is the coumarin glucoside aesculin.

10/White Snakeroot (Ageratina altissima)

White Snakeroot, also known as White Sanicle or Tall Boneset, is a poisonous perennial herb in the familyAsteraceae, native to eastern North America. This plant used to be placed in the genus Eupatorium, as did Smaller White Snakeroot (A. aromatica), a nonaromatic plant despite its name; it has less coarsely toothed leaves, the upper ones stalkless. White Snakeroot contains the toxin tremetol; when the plants are consumed by cattle, the meat and milk become contaminated with the toxin. When milk or meat containing the toxin is consumed, the poison is passed onto humans. If consumed in large enough quantities, it can cause tremetol poisoning in humans. The poisoning is also called milk sickness, as humans often ingested the toxin by drinking the milk of cows that had eaten snakeroot.