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
 

Photo: © Kerry Woodfield
By silhouette.


18th June 2012, sand quarry, Marshside, Sefton Coast. Photo: © RWD
Grows up to 2m in height and sometimes taller to 2.5m! The terminal umbel )of the main stem) has bisexual flowers whereas the flowers on the other (lateral) umbels are male mixed with bisexual flowers.


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


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


Photo: © Kerry Woodfield
Partially opened flowers display a creamy-green colour; they will all be dazzle white when fully opened.


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
The petals are white and the outer petals do not radiate out noticeably longer than any other petals.


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.


Photo: © Kerry Woodfield
The 5 to 6 bracts beneath the main umbels (bottom left and right) are narrowly triangular to lanceolate and angled downwards (deflexed) with a wide white margin (scarious) [bottom half of photo]. The 3-6 bracteoles below the satellite umbeletts are often conjoined near their bases [top half of photo].


Photo: © Kerry Woodfield
The bracts below the umbels have a white margin.


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. The whole plant is glabrous (without hairs [except for the scabrid nature (rough feel) to the rays of the umbels)


Photo: © Kerry Woodfield
The stems are hollow (if cut open - but do not get any sap on your skin!) and characteristically blotched purple.


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 mid-green (except where it is purple such as the characteristic blotches on the main stem) but Your Author thinks these lower leaves are a bit on the chloretic side. This leaf conforms to the overall triangular outline and is 4-pinnate, being near the base of the plant.


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


Photo: © Kerry Woodfield
A typical leaf, triangular in overall outline. Basal leaves are between 2- and 4-pinnate. This leaf is 3-pinnate.


Photo: © Kerry Woodfield
The fruits are between 2.5-3.5mm, ovoidal, slightly flattened in one direction. Each in two halves (as is usual for Umbellifers) the two halves having 5 ridges each, the ridges having slight undulations or knobbles on, especially in the top half.


Photo: © Kerry Woodfield
The two thin white styles at the top are bent over the stylopodium outwards. The stylopodiums here have a white margin


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 of 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 penetrate 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 exhibits a burning sensation in the mouth and smells foetid or 'mousey', contributing to the awful smell of Hemlock. [Coniine might not be found in Cowbane (Cicuta virosa) despite the synonym Cicutine which is (sometimes) applied to Coniine - Cowbane contains a differing highly toxic component, Cicutoxin, which is a polyyne rather than a piperidine - the alias Cicutin which is sometimes applied to Coniine 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. Both stereoisometric forms are present in Hemlock. 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, as shown above right, is present in Hemlock but 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 has 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]