SOLANACEAE

The Solanaceae or nightshade family comprises some 2700+ species of trees, shrubs, and climbers of cosmopolitan distribution. They usually bear simple alternate leaves, symmetrical 5-lobed flowers, and fruits in the form of capsules or berries. The nightshade is the most iconic family of poisonous plant. It contains species that are invaluable to the agricultural and pharmaceutical industry. Almost all nightshade species produce chemical toxins including alkaloids, steroids and vanilloids. Even food crops such as potato, tomato and eggplant contain steroidal alkaloids called solanines (saponins). The nightshade saponins act like soap, they disrupt or dissolve cell membranes, much like soap washing off fats and oils. This causes inflammation, cell death and multi-organ failure. Human poisoning due to ingestion of edible nightshades, particularly raw potato shoot is rare but well-documented. Another important food crop the chili (Capsicum spp.) produces a vanilloid toxin called capsaicin, which causes spiciness. Capsaicin activates human heat receptors called the TRPV-1. Despite its pain-inducing effect, sensory overload by capsaicin can  lead to numbness. Pure capsaicin is investigated as a drug to treat chronic pain. Other Solanaceae alkaloids are diverse and extremely potent, such as tropane alkaloids and nicotine. Those will be discussed in the section [Science].

One of the most iconic poisonous plants, the Datura belongs to the nightshade family (Solanaceae).

The tobacco plants Nicotiana tabacum and Nicotiana rustica are  cultivated worldwide for the ‘smoking industry’, which causes 8 million human deaths annually! This makes tobacco the most deadly plant known to humans. Even those who are not smoking can be harmed by second-hand smoke. Tobacco smoking is the leading cause of cancer deaths and chronic lung diseases. This is due to the presence of an addictive pyridine alkaloid called nicotine, which is a stimulant in low quantities, but fatal in overdose (less than 0.1 grams can be lethal to an adult human). Human skin readily absorbs nicotine, as tobacco farmers are afflicted with an occupational disease called 'Green Tobacco Sickness'. Another Nicotiana species the tree tobacco (N. glauca) produces an even more potent nicotinic alkaloid called anabasine, which is often fatal if ingested. Pure nicotine was once produced as an insecticide for organic farming, but it has been replaced by less toxic, semi-synthetic analogs called neonicotinoids. Neonicotinoids like imidacloprid and acetamiprid are some of the most important and widely used agricultural pesticides. However, they are implicated in colony collapse disorder (CCD) of bees.

Tobacco (Nicotiana tabacum)

Flowering tobacco (Nicotiana alata). This species is common in the ornamental plant trade, but it is less poisonous compared to other Nicotiana species (little to no nicotine content).

Aztec tobacco (Nicotiana rustica) contains the highest nicotine content of all tobacco species (9% w/w). It is three times more potent than N. tabacum. It also contains harmala alkaloids, which are monoamine oxidase inhibitors. N. rustica is used as a ritual entheogen by South American tribes.

Nicotiana rustica, flower close-up.

Nicotiana rustica, flower cluster

While tobacco is an insidious killer, the star of poisonous nightshades is none other than the tropane alkaloid containing plant, e.g., the deadly nightshade (Atropa belladonna), angel’s trumpet (Datura and Brugmansia), mandrake (Mandragora), and henbane (Hyoscyamus and Scopolia). The tropane alkaloids atropine, hyoscine and hyoscyamine block human body’s involuntary nervous system. They induce a set of symptoms called the anticholinergic toxidrome (toxic syndrome), which is characterised by dilated pupils, inability to sweat and urinate, dry mouth, flushed skin, increased heart rate, delirium (inability of the brain to perceive ‘reality’), and death by respiratory depression. Tropane alkaloids are exploited since antiquity well into modernity as medicine, poison and ritual hallucinogen. The plants have such profound influence on humans, they are incorporated into local legend, history and even religion. Today, tropane alkaloids and their semi-synthetic derivatives are some of the most valuable human medicines. They have probably saved more lives than they had ended in the past.

Golden Angel's trumpet (Brugmansia x cubensis).  This is a hybrid cultivar of B. aurea X B. suaveolens X B. versicolor. It has very long petal tip and calyx that sheaths the narrowest region of corolla tube (B. aurea predominant). The leaves are toothed and less hairy compared to other cultivars.

White Angel's trumpet (Brugmansia suaveolens). Note: The narrowest region of corolla tube protrudes out of calyx. This species/ hybrid cultivar has hairy round leaves, seldom toothed.

Pink Angel's trumpet (Brugmansia suaveolens)

White Angel's trumpet (Brugmansia x candida). This is a hybrid cultivar of B. aurea X B. versicolor. It has long petal tips and calyx that sheaths the narrowest region of corolla tube. The leaves are large, densely haired, seldom toothed

Sacred Datura (Datura innoxia)

Note: Datura innoxia is closely related to D. wrightii and D. metel (section Dutra). D. innoxia often has stigma that is shorter than anthers. Its seeds have several marginal furrows. D. innoxia can be distinguished from D. wrightii by close examination of the stem indumentum. D. innoxia has long erect multicellular glandular hairs; D. wrightii has retrose eglandular hairs.

 Datura wrightii (purple variant). D. wrightii is very closely related to D. innoxia, the two can potentially form natural hybrids. D. wrightii often has stigma that long exceeds the anthers. Its seeds have a single marginal furrow. See stem indumentum (above) for species confirmation.

Datura wrightii, flower.

 Datura wrightii, lateral view of flower.

Hindu Datura (Datura metel var. metel, single white flower, pre-bloom).

Datura metel var. metel, single white flower, full bloom.

Datura metel var. metel (single white), flower front view. Note: Datura metel has much wider corolla 'mouth' compared to Datura innoxia and Datura wrightii.

Datura metel var. metel (single white), locality Bali, Indonesia. This is actually my first Datura and probably the one that started my whole journey of creating a Poison Garden.

Hindu Datura (Datura metel var. fastuosa, double purple flower). Horticulture cultivar 'Purple Ballerina'.

Datura metel var. fastuosa hort. 'Purple Ballerina', flower lateral view. Note: This variant can sometimes produce up to 3-4 layered flower.  

Datura metel var. fastuosa hort 'Purple Ballerina', flower front view.

Datura metel var. fastuosa (single purple / white) variant. Note: The purple pigment anthocyanin develops intensely (and unevenly) on parts of the flower that are exposed to sunlight, giving a 'stripe' appearance.

Datura metel var. fastuosa, single purple variant.

Datura metel var. chlorantha. Note: chlorantha means green flower, probably alluding to the immature greenish flower.

Datura metel var. chlorantha. Horticulture cultivar 'Golden Queen'.

Datura metel var. chlorantha, close up of flower.

Datura metel 'Triple White'. This is likely a pale flower cultivar of D. metel var. chlorantha.

Jimson weed (Datura stramonium var. tatula).

Datura stramonium var. tatula, unusual flower with six united petals.

Datura stramonium var. tatula, lateral view.

Datura stramonium var. tatula, growth form

Datura stramonium var. stramonium, front view of flower. The variety bears pure white flowers.

Datura stramonium var. stramonium. Lateral view of flower.

Datura stramonium var. stramonium.

Cup of gold (Solandra maxima). The genus Solandra is closely related to the Datura, and it is equally poisonous. Solandra maxima can be found naturalised in the highlands of Peninsular Malaysia.

Chalice vine (Solandra grandiflora). This species is more adapted to the heat of lowland Malaysia.

Solandra grandiflora, flower lateral view.

The Shoo-fly plant (Nicandra physalodes) is closely related to the Datura. While its toxins are not well-understood, this species is known to cause poisoning to livestock. It is considered as an invasive species in parts of the world. It appears to adapt well and produce viable seeds in Peninsular Malaysia.

Nicanrdra physalodes, flower and immature seedpod.

Some lesser-known nightshades are also highly poisonous, particularly the genera Cestrum (jessamine) and Brunfelsia (lady of the night). Both are woody shrubs that produce intensely fragrant flowers. The day blooming jessamine (Cestrum diurnum) contains vitamin-D3 glycosides in its leaves that can cause vitamin D toxicosis when consumed in large quantities. Vitamin D overdose causes weakened bones and abnormally high blood calcium level. This leads to kidney stone formation and the calcification of blood vessels and organs. The victim's body is gradually turned to bone! The willow leaf jessamine (Cestrum parqui) and golden jessamine (Cestrum aurantiacum) are even more poisonous because they contain the metabolic poison carboxyparquin, which is a structural analog of carboxyatractyloside. Carboxyparquin prevents the body from using energy. Victims suffocate from the inside out, then die of multi-organ failure. Cestrum species are responsible for epidemics of cattle deaths in South America, particularly during periods of drought when animals have limited choices to graze. Last but not least, the lady of the night (Brunfelsia americana) and the yesterday today tomorrow (Brunfelsia calycina) contain a neurotoxic pyrrolidine alkaloid called brunfelsamidine, which is known to cause severe convulsion and multi-organ failure in domestic animals. For unknown reasons, dogs tend to gorge on Brunfelsia berries and become fatally poisoned.

Chilean jessamine (Cestrum parqui). This is one of the most poisonous Cestrum species, it causes massive poisoning and death to livestocks due to the presence of a metabolic toxin called carboxyparquin.

Cestrum parqui, berry.

Day blooming jessamine (Cestrum diurnum). It is sometimes said that Cestrum diurnum flowers smell like chocholate, but that is apparently a case of acquired taste! This species poisons its victim with an overdose of vitamin D, turning the organs and blood vessels into bone!

Queen of the night jessamine (Cestrum nocturnum). This is one of the most intensely fragrant ornamental flowers of Malaysia, and it is especially pleasant during cool rainy nights. Cestrum nocturnum contains the alkaloid toxin nicotine.

The yesterday today and tomorrow (Brunfelsia calycina) is well-known for its colour changing flowers from purple to lilac to white over three consequitve days. While the reason behind this colour change is unclear, it is due to the oxidative degradation of a purple pigment called anthocyanin.

Lady of the night (Brunfelsia lactea). The flower starts off white in colour, turning a cream yellow as it age. It emits a powerful fragrant akin to that of the Datura.

Less poisonous Solanaceae species with edible berries:

Black nightshade (Solanum nigrum), immature fruits. The black nightshade is potentially poisonous due to the presence of solanine alkaloids. It appears that the green berries are most poisonous and inedible. The plant foliage is edible but may accumulate high level of nitrates.

Solanum nigrum, matured fruit. Likely edible. 

Sticky nightshade (Solanum sisymbriifolium). This species produces sour but edible berries sometimes called 'litchi tomato'. All parts of the plant have sharp prickles.

Solanum sisymbriifolium, berries.