Aconitum

The name aconitum comes from the Greek word ἀκόνιτον, which may derive from the Greek akon for dart or javelin, the tips of which were poisoned with the substance, or from akonae, because of the rocky ground on which the plant was thought to grow.^[7] The Greek name lycoctonum, which translates literally to "wolf's bane", is thought to indicate the use of its juice to poison arrows or baits used to kill wolves.^[8] The English name monkshood refers to the cylindrical helmet, called the galea, distinguishing the flower.^[4]

The dark green leaves of Aconitum species lack stipules.^[9] They are palmate or deeply palmately lobed with five to seven segments. Each segment is trilobed^[10] with coarse sharp teeth. The leaves have a spiral (alternate) arrangement. The lower leaves have long petioles.

The tall, erect stem is crowned by racemes of large blue, purple, white, yellow, or pink zygomorphic flowers with numerous stamens. They are distinguishable by having one of the five petaloid sepals (the posterior one), called the galea, in the form of a cylindrical helmet, hence the English name monkshood.^[4] Two to 10 petals are present.^[10] The two upper petals are large and are placed under the hood of the calyx and are supported on long stalks. They have a hollow spur at their apex, containing the nectar. The other petals are small and scale-like or nonforming. The three to five carpels are partially fused at the base.

The fruit is an aggregate of follicles,^[10] a follicle being a dry, many-seeded structure.

Unlike with many species from genera (and their hybrids) in Ranunculaceae (and the related Papaveroideae subfamily), there are no double-flowered forms.

Aconitum species have been recorded as food plant of the caterpillars of several moths. The yellow tiger moth Arctia flavia, and the purple-shaded gem Euchalcia variabilis are at home on A. vulparia.^[13] The engrailed Ectropis crepuscularia, yellow-tail Euproctis similis, mouse moth Amphipyra tragopoginis, pease blossom Periphanes delphinii, and Mniotype bathensis, have been observed feeding on A. napellus. The purple-lined sallow Pyrrhia exprimens, and Blepharita amica were found eating from A. septentrionale. The dot moth Melanchra persicariae occurs both on A. septentrionale and A. intermedium. The golden plusia Polychrysia moneta is hosted by A. vulparia, A. napellus, A. septentrionale, and A. intermedium. Other moths associated with Aconitum species include the wormwood pug Eupithecia absinthiata, satyr pug E. satyrata, Aterpia charpentierana, and A. corticana.^[14] It is also the primary food source for the Old World bumblebees Bombus consobrinus and Bombus gerstaeckeri.^[15][16][17]

Aconitum flowers are pollinated by long-tongued bumblebees.^[18] Bumblebees have the strength to open the flowers and reach the single nectary at the top of the flower on its inside.^[18] Some short-tongued bees will bore holes into the tops of the flowers to steal nectar.^[18] However, alkaloids in the nectar function as a deterrent for species unsuited to pollination. The effect is greater in certain species, such as Aconitum napellus, than in others, such as Aconitum lycoctonum.^[19] Unlike the species with blue-purple flowers such as A. napellus, A. lycoctonum—which has off-white to pale yellow flowers, has been found to be a nectar source for butterflies.^[18] This is likely due to the nectary flowers of the latter being more easily reachable by the butterflies; however, the differing alkaloid character of the two plants may also play a significant role or be the primary influence.^[18]

The species typically utilized by gardeners fare well in well-drained evenly moist "humus-rich" garden soils like many in the related Helleborus and Delphinium genera, and can grow in the partial shade. Species not used in gardens tend to require more exacting conditions (e.g. Aconitum noveboracense). Most Aconitum species prefer to have their roots cool and moist, with the majority of the leaves exposed to sun, like the related Clematis. Aconitum species can be propagated by divisions of the root or by seeds, with care taken to avoid leaving pieces of the root where livestock might be poisoned. All parts of these plants should be handled while wearing protective disposable gloves.^[4] Aconitum plants are typically much longer-lived than the closely related delphinium plants, putting less energy into floral reproduction. As a result, they are not described as being "heavy feeders" (needing a higher quantity of fertilizer versus most other flowering plants)—unlike gardeners' delphiniums. As with most in the Ranunculaceae and Papaveraceae families, they dislike root disturbance. As with most in Ranunculaceae, seeds that are not planted soon after harvesting should be stored moist-packed in vermiculite to avoid dormancy and viability issues. The German seed company Jelitto offers "Gold Nugget" seeds that are advertised as utilizing a coating that enables the seed to germinate immediately, bypassing the double dormancy defect (from a typical gardener's point of view) Aconitum—and many other species in Ranunculaceae genera—use as a reproductive strategy. By contrast, seeds that are not immediately planted or moist-packed are described as perhaps taking as long as two years to germinate, being prone to very erratic germination (in terms of time required per seed), and comparatively quick seed viability loss (e.g. Adonis). These issues are typical for many species in Ranunculaceae, such as Pulsatilla (pasqueflower).

Members of the genus Aconitum contain substantial amounts of highly toxic alkaloids (such as aconitine, mesaconitine, and pseudaconitine), especially in their roots and tubers. Ingestion of as little as 2 mg of aconitine or 1 g of plant material may cause death from respiratory paralysis or heart failure.^[3]

Mild to severe toxicity may be experienced from skin contact.^[27] Symptoms such as numbness and tingling and feelings of coldness in the face and extremities usually appear within one hour of exposure, and sometimes almost immediately.^[28] Other features may include nausea, vomiting, diarrhea, sweating, dizziness, difficulty in breathing, headache, and confusion.^[4] In severe poisoning, sensations of tingling and numbness spreads to the limbs, and pronounced motor weakness occurs. Cardiovascular features include low blood pressure and abnormal heart rhythm.^[29][30] Death usually occurs within two to six hours in fatal poisoning.^[29]

Treatment of poisoning involves close monitoring of blood pressure and cardiac rhythm. Gastrointestinal decontamination with activated charcoal can be used if administered within an hour or so of ingestion.^[31] Drugs such as atropine, lidocaine, and amiodarone may be used to treat dysrhythmias. Cardiopulmonary bypass, ECMO, and hemoperfusion may be useful if symptoms are refractory to treatment with these drugs.^[32]

Genetic analysis suggests that Aconitum as it was delineated before the 21st century is nested within Delphinium sensu lato, that also includes Aconitella, Consolida, Delphinium staphisagria, D. requini, and D. pictum.^[1] Further genetic analysis has shown that the only species of the subgenus "Aconitum (Gymnaconitum)", "A. gymnandrum", is sister to the group that consists of Delphinium (Delphinium), Delphinium (Delphinastrum), and "Consolida" plus "Aconitella". To make Aconitum monophyletic, "A. gymnandrum" has now been reassigned to a new genus, Gymnaconitum. To make Delphinium monophyletic, the new genus Staphisagria was erected containing S. staphisagria, S. requini, and S. pictum.^[46]

Aconitum chasmanthum is listed as critically endangered,^[47] Aconitum heterophyllum as endangered,^[48] and Aconitum violaceum as vulnerable due to overcollection for use as an herbal medicine.^[49]

Aconite and wolfsbane have been understood to be poisonous from ancient times, and are frequently represented as such in literature. In Greek mythology, the goddess Hecate is said to have invented aconite,^[52] which Athena used to transform Arachne into a spider.^[53][54] Medea is also said to have attempted to poison Theseus with a cup of wine poisoned with wolf's bane.^[55]

In the poem Metamorphoses, Ovid tells of the herb coming from the slavering mouth of Cerberus, the three-headed dog that guarded the gates of Hades.^[53][56] In his Natural History, Pliny the Elder supports the legend that aconite came from the saliva of the dog Cerberus when Hercules dragged him from the underworld.^[53][57] As the veterinary historian John Blaisdell has noted, symptoms of aconite poisoning in humans bear similarity to those of rabies: frothy saliva, impaired vision, vertigo, and finally, coma; thus, ancient Greeks could have believed that this poison, mythically born of Cerberus's lips, was literally the same as found inside the mouth of a rabid dog.^[58]

• 
  Aconitum napellus
• 
  Trailing white monkshood (A. reclinatum)
• 
  Southern blue monkshood (A. uncinatum)
• 
  Wild Alaskan monkshood (A. delphinifolium) is a flowering species that belongs to the family Ranunculaceae. The picture was taken in Kenai National Wildlife Refuge in Alaska.

• Rufus T. Bush, industrial tycoon who died of accidental aconite poisoning