HEMLOCK

Conium maculatum

Carrot Family [Apiaceae]

month8jun month8june month8jul month8july month8aug

status
statusZarchaeophyte
 
flower
flower8white
 
morph
morph8actino
 
morph
morph8zygo
 
petals
petalsZ5
 
type
typeZumbel
 
stem
stem8round
 
stem
stem8fluted
 
stem
stem8hollow
 
smell
smell8foetid
foetid
toxicity
toxicityZsevere
 
contact
contactZhigh
 

18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Grows up to 2m in height and sometimes taller to 2.5m!


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Paler green stems and white umbels. [Spiky darker-green foliage of Spear Thistle is behind]


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Each branch usually has a pinnate leaf at the branching point.


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Umbels are compound.


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Bracts on the umbel number 5-6 and are narrowly triangular to lanceolate, deflexed (bent downwards) and have a wide scarious (thin and dry, not green) margin. The bracteoles on the umbellets number 3-6, are widened and often connate (fused together) at the base.


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Umbels have 10-20 subequal (not quite equal in length) scabrid (rough to the touch with minute stiff hairs) rays, each with an umbellet of white flowers. The lower umbels have a mix of hermaphrodite and male flowers. The terminal umbel (near the top of the plant) has hermaphrodite flowers only.


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Flowers white and almost, but not quite, actinomorphic. That is, some are hemi-zygomorphic.


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Flowers are without sepals underneath.


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Smaller upper leaves emerge from stem bifurcations and have a short sheathing base. Stems hollow, upper stems furrowed, lower stems with purple striations and blotches.


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Lower leaves larger and between 2 to 4-pinnate.


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Lower stems striated or blotched with purple, a reliable characteristic feature of Hemlock. Leaf with short sheath at stem bifurcations.


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Lower leaves larger and pinnate to a higher order. Petioles (stalks) of lower leaves are longer.


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
The whole plant is pale green (except where it is purple) but Your Author doesn't think the leaves are usually this pale.


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Leaves are finely cut.


Easily confused with : many umbellifers with similar foliage, but the purplish blotches on the stem is indicative and only rarely absent. The foetid/mousey smell also helps ID, but careful not to get any juices on your skin - the toxin readily passes through skin.

Similar to : Cow Parsley (Anthriscus sylvestris) and Rough Chervil (Chaerophyllum temulum) but it is hairless and usually with many purplish blotches on the stem.

Not to be semantically confused with : Hemlock Water-Dropwort (Oenanthe crocata) [a highly-poisonous plant with similar name in a differing genus but within the same Umbellifer family Apiaceae]. Nor with Western Hemlock aka Western Hemlock-Spruce (Tsuga heterophylla), a very tall coniferous tree.

It is a biennial, producing basal leaves in its first year followed by flowers in the second. The specific epithet maculatum means blotchy or spotted, which the lower stems are: a purplish-red. It is far more common in the South of England, much less so in the North. Found by roads, on stream and river-banks, beside ditches and on other waste ground and rough grassland - on damp soil.

CONIINE-TYPE PIPERIDINE ALKALOIDS

Coniine
Coniine (aka Conicine and Cicutine), the first ever alkaloid to be synthesized in the laboratory, is one of the simplest alkaloids known along with Nicotine, but unlike Nicotine, is one of the most poisonous. It is based upon a Piperidine ring which contains a heterocyclic nitrogen atom with a short propane side-chain. Coniine has similar clinical effects to nicotine, both being biphasic, with first a stimulatory action, followed by Central Nervous System depression and muscle paralysis of respiratory muscles, when death occurs quickly. A fatal dose is estimated to be about 5mg of coniine ingested orally per kilogram of body mass, or less than 0.1 gram for a typical body-weight. Coniine is present in the leaves of Hemlock (at a concentration 2%) and in the un-ripe fruits and roots. Consuming just 6 - 8 leaves will kill. The symptoms may progress from drowsiness, paraesthesias (loss of sensation / 'pins and needles'), weakness, nausea, ataxia (un-coordination), extreme salivation, bradycardia (slow heart-beat) followed by tachycardia (fast heart-beat). Death is due to respiratory arrest, and occurs within 3 hours of a toxic dose. There exists a treatment regime for the various symptoms, but it might not lead to a successful outcome. Hemlock has at least five similar toxic alkaloids within it making estimation of toxic dose from Hemlock poisoning difficult to assess. Poisoning can also result from inhalation of coniine or from absorption by skin, as it is a small enough molecule to be both a volatile liquid and to permeate the skin with ease.

Coniine is also found in Fool's Parsley (Aethusa cynapium) and the non-native carnivorous plant Yellow Pitcher Plant (Sarracenia flava) which is native in the southeastern United States. Coniine has a burning sensation in the mouth and smells foetid or 'mousey', contributing to the awful smell of Hemlock. [It might not be found in Cowbane (Cicuta virosa) despite the synonym Cicutine which is (sometimes) applied to Coniine for that contains a differing highly toxic component, Cicutoxin, which is a polyyne rather than a piperidine - the alias might just might be a case resulting from mistaken identity of the two plants - for both plants are Umbellifers].

Coniine can exist in two differing stereoisomers, the D-(S) and L-(R) forms (and a racemic mixture of the two known as rac-Coniine), with one stereoisomer being slightly less toxic than the other but there is only about a 12% difference. It is present in Hemlock as a mixture of both stereoisomeric forms. It slowly oxidises in air. Coniine has been used as a poison-arrow toxin and as a death sentence for naughty Greeks, the most famous of whom was Socrates.

The following four further poisonous alkaloids found within Hemlock are of less importance, presumably because of their lower concentration rather than because of any lesser toxicity? Your Author knows not, and has not been able to ascertain.



Hemlock is at its most toxic in the spring when the precursor molecule, γ-Coniciene (L-PropenylPiperidine) is at its highest concentration. γ-Coniciene is converted into Coniine (and subsequently other similar compounds as shown here) within the plant.

N-MethylConiine
Is present in Hemlock only in smaller quantities than Coniine, and is similar to Coniine.


Conhydrine and PseudoConhydrine are isomers of each other, differing only in the position of the -OH group. Conhydrine exhibits a foetid odour similar to that of Coniine.


  Conium maculatum  ⇐ Global Aspect ⇒ Apiaceae  

Distribution
 family8Carrot family8Apiaceae

 BSBI maps
genus8Conium
Conium
(Hemlock)

HEMLOCK

Conium maculatum

Carrot Family [Apiaceae]