GREAT LETTUCE

LETTUCE OPIUM, WILD LETTUCE

Lactuca virosa

Daisy & Dandelion Family [Asteraceae]

Flowers:
month8jun month8june month8jul month8july month8aug month8sep month8sept

Pappus: pappusZpossible (white)
pappus8jul pappus8july pappus8aug pappus8sep pappus8sept pappus8oct

status
statusZnative
 
flower
flower8bicolour
 
flower
flower8yellow
 
inner
inner8red
 
morph
morph8actino
 
petals
petalsZMany
 
stem
stem8round
 
stem
stem8milkysap stem8milkylatex
 
stem
stem8spines stem8thorns
 
toxicity
toxicityZmedium
 

1st June 2010, Sandscale Haws, Cumbrian Coast. Photo: © RWD
A stout plant which grows up to 2m tall; taller and stouter than the similar Prickly Lettuce.


1st June 2010, Sandscale Haws, Cumbrian Coast. Photo: © RWD
Leaves alternate and darker green than those of Prickly Lettuce and less deeply divided. Also, un-like Prickly Lettuce the leaves have a red rather than white mid-rib and are often flushed red, and the main stem is more flushed with purple.


1st June 2010, Sandscale Haws, Cumbrian Coast. Photo: © RWD
The leaves have a tendency to stick up vertically, and the obverse may follow the sun. Stems have sparse long hairs.


1st June 2010, Sandscale Haws, Cumbrian Coast. Photo: © RWD
Obverse of leaves has long prickles on the mid-rib and major veins.


1st June 2010, Sandscale Haws, Cumbrian Coast. Photo: © RWD
The prickles on the veins on the reverse side of the leaves.


1st June 2010, Sandscale Haws, Cumbrian Coast. Photo: © RWD
Several yellow dandelion-type flowers near and at the top. Prickly leaves at stem junctions.


1st June 2010, Sandscale Haws, Cumbrian Coast. Photo: © RWD
The un-opened flowers have a lower bulge and a neck near the top.


1st June 2010, Sandscale Haws, Cumbrian Coast. Photo: © RWD
The underside of the outer ray florets has a reddish central stripe. Long hairs or weak prickles on sepals.


1st June 2010, Sandscale Haws, Cumbrian Coast. Photo: © RWD
Broken stems exude a poisonous milky sap.


Despite the synonym Opium Lettuce it is not related to: Opium Poppy

Related to: ordinary Garden Lettuce. If lettuces are allowed to grow then they 'bolt' producing a long stalk and prickly leaves much like as here.

Some similarities to : Prickly Lettuce, but that has much a finer pitch of the teeth on the edge of the leaves, and the mid-rib of the leaves is not purple as in Great Lettuce, but white. Prickly Lettuce also has lighter green leaves, a green stem, and smells slightly foetid.

Possibly confusable with: Rough Sow-thistle and Smooth Sow-Thistle.

Uniquely identifiable characteristics

Distinguishing Feature :

Great Lettuce has a very stout and reddish stem, with long flexible prickles on it. The leaves are darkish green with reddish tinges and wavy edged and teeth sharpish teeth on the periphery and on the underside of the red mid-rib. The stem exudes a milky liquid when broken (but so does Prickly Lettuce).

Great Lettuce is one of the few Daisy & Dandelion Family members that has a red stripe on the rear of the outer ray florets. Others include Cat's-ear, Smooth Hawk's-Beard, Mouse-ear Hawkweed and Beaked Hawk's-beard.

It inhabits disturbed and waste ground, especially near the sea.

The milky sap which exudes from broken stems is not called laudenum as has been suggested elsewhere, and despite that name of Opium Lettuce being one of its synonyms, it does not contain any opiates, but rather several lactones with pharmacological properties only similar to that of opium. The latex that can be prepared from the milky sap is called Lactucarium; it was prescribed as a tincture in the 1800's for use in cough medicines and lozenges. All lettuces contain some amount of this narcotic liquor, even garden lettuce, although the consumer may have to eat considerable quantities of lettuce before any harmful effects become apparent.

The native American Hopi tribe used to smoke the dried resinous sap from the broken stems. It induced dream-like trances and lucid dreaming.

The milky sap contains the lactones Lactucin and two derivatives, Lactucopicrin and 11-,13-dihydrolactucin. Lactucopicrin has acetylcholineesterase inhibitory actions, whilst Lactucin is an agonist against the Adenoside receptors. These extracts can help induce sleep, but are also poisonous in excess, death can result.

OTHER CHEMICAL CONSTITUENTS

Great Lettuce also contains flavonoids, coumarins and N-methyl-phenylethylamine (aka NMPEA), which is chemically similar to the manufactured pharmacological drug Methamphetamine.


NMPEA occurs naturally in humans in trace trace amounts and acts as a neuromodulator. Like the derivative PhenylEthylAmine (PEA) it is an alkaloid. It acts similar to Epinephrine (aka Adrenaline) but exhibits only 1/350th the potency. It has similar pharmacological and toxicological properties as Amphetamine, PhenylEthylAmine and other Methyl-PhenylEthylAmines (or at least it does in rats, which have similar, but not identical, biological mechanisms to humans).


  Lactuca virosa  ⇐ Global Aspect ⇒ Asteraceae  

Distribution
 family8Daisy & Dandelion family8Asteraceae

 BSBI maps
genus8Lactuca
Lactuca
(Lettuces)

GREAT LETTUCE

LETTUCE OPIUM, WILD LETTUCE

Lactuca virosa

Daisy & Dandelion Family [Asteraceae]

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