ROSY GARLIC

Allium roseum

Onion & Garlic Family [Alliaceae]

month8may month8jun month8june

status
statusZneophyte
 
flower
flower8bicolour
 
flower
flower8lilac flower8pink
 
flower
flower8white
 
inner
inner8yellow
 
morph
morph8actino
 
petals
petalsZ6
(3 + 3)
type
typeZglobed
 
type
typeZbell
 
stem
stem8round
 
smell
smell8yyy
garlic

16th June 2010, a garden, Colwyn Bay, North Wales. Photo: © RWD
Mainly a garden plant growing to 75cm.


16th June 2010, a garden, Colwyn Bay, North Wales. Photo: © RWD
The globular clusters are very open, with maybe up to 20 rose-pink flowers.


16th June 2010, a garden, Colwyn Bay, North Wales. Photo: © RWD
The flower head is about 8cm across, with the flowers singly on 3cm long thin stalks.


16th June 2010, a garden, Colwyn Bay, North Wales. Photo: © RWD
Bulbils in the centre. Unlike several other plants belonging to the Allium Genus, Rosy Garlic never displays bulbils alone without the flowers also being present (although it can have flowers alone without bulbils).


16th June 2010, a garden, Colwyn Bay, North Wales. Photo: © RWD
The flowers are mostly bell-shaped rarely opening wide.


16th June 2010, a garden, Colwyn Bay, North Wales. Photo: © RWD


16th June 2010, a garden, Colwyn Bay, North Wales. Photo: © RWD
With three inner and three outer petals (actually tepals), all a lilac colour with whitish parts. Six white stamens topped by cream coloured anthers. The stamens are shorter than the tepals (whereas in Keeled Garlic they are longer than the tepals). The bulbils are like miniature Red Onions and wrapped in a whitish thin papery sheath that peels away.


16th June 2010, a garden, Colwyn Bay, North Wales. Photo: © RWD
Six creamy anthers.


16th June 2010, a garden, Colwyn Bay, North Wales. Photo: © RWD
And a longer white tapering stigma in the centre topped by a much smaller pale-yellow blob.


24th June 2012, Home Counties. Photo: © Richard Eyre
Underneath the bulbils are short papery bracts (Keeled Garlic has extremely long and narrow paper bracts).


16th June 2010, a garden, Colwyn Bay, North Wales. Photo: © RWD
The bulbils have red 'skins' and are almost spherical.


16th June 2010, a garden, Colwyn Bay, North Wales. Photo: © RWD
The stems are glaucous green, thin and stiff. The leaves long and linear, flat and scarcely keeled, apt to bend over.


Can be mis-identified as : Crow Garlic (Allium vineale) but that does not usually have flowers and the bulbils are a deeper beetroot colour. Another similar species, Sand Leek also has beetroot coloured bulbils rather than the Red Onion red of Rosy Garlic. Garlic too has different coloured bulbils, being paler, and the flowers are a different shade.

Some similarities to : Wild Leek (Allium ampeloprasum) which has a globular cluster of similarly shaped and similarly coloured pink flowers, but the number of flowers is so high as to completely fill the sphere.

It can have flowers alone, or flowers with bulbils, but never bulbils alone.

It is found growing in the wild mainly down south near the coast in rough or cultivated ground, hedgerows, old dunes or waysides, but is much more likely to be found in a Garden, from where they frequently escape. It is an introduced plant that has become well naturalised.

SULFUR CONTAINING COMPOUNDS found in ROSY GARLIC

Rosy Garlic is used in folk medicine for the treatment of headache and rheumatism. It is also used for the treatment of bronchitis, for inhalation to alleviate the bronchial symptoms of common cold and to reduce a high body temperature. It is also used as a food ingredient by the foodstuff industry and as a development base for new phytomedicinal pharmaceuticals. Extracts of the plant have antimicrobial properties against P. aeroginosa, E. coli and M. luteus. It exhibits the largest activity against Gram negative bacteria.

Many of the compounds within Rosy Garlic contain sulfur, just like they do in Onions and Garlic. According to many authors, it is the sulfurous compounds within these plants which are responsible for both the odour and taste of many plants belonging to the Allium genus, and also to the associated health benefits.


DimethylTrisulfide (DMTS) is found amongst the volatile compounds emitted by cooked onions, leeks, broccoli, cabbage and noted as a component of the un-palatable aroma of stale beer. It has a foul odour detectable in air at a concentration of just 1 part in 1012. It is a decomposition product of decaying flesh and attracts blowflies (bluebottles) searching for hosts. It is also the malodorous compound emitted by the Common Stinkhorn (Phallus impudicus) fungus. It has been used as a bait in insect traps.

Methional [aka 3-methylsulfanylpropanal or thio-4-pentanal] is the main constituent in the essential oil from Rosy Garlic. It is a skin irritant and may cause cyanosis of the extremities. Inhalation of the vapours causes irritation of the respiratory tract and may lead to pulmonary oedema. Exposure to high concentrations of mercaptans can produce unconsciousness, cyanosis, tachycardia, cold extremities, depression of the CNS and asphyxiation. In small amounts it is characteristic of boiled potatoes when used as a food additive.


1-propenyl-methyl-disulfide [aka 1-(methyldisulfanyl)prop-1-ene or allylmethyldisulfide] and 2-Propenyl-methyl-disulfide [aka 2-methyl-1,3-dithiolane] used as a flavoring ingredient



Another similar compound is Allyl­propyl­disulfide (APDS), which is a pale yellow liquid with a strong aroma and spicy taste. It is also present in Garlic and Onion (Allium cepa) and causes the eyes to lachrymate when Onions are sliced. It evaporates when onions or garlic are cooked to leave a sweeter taste. It exhibits a hypoglyacaemic effect even when administered by mouth and may be useful to control (lower) the blood glucose level in hypoglycaemic diabetics.



2,5-dimethylthiophene is used as an odorant and flavoring agent with a sulfurous type odour. It too is found in Onion.



Methiine (aka Methiin or S-methyl-L-cysteinsulfoxide)) is a non-proteinogenic amino acid (NPAA) which can mimic the real amino acid Cystein. Methiin is also found in other Allium species but is dominant in Chives (Allium schoenoprasum).



Alliin is the S-oxide of S-Allyl Cysteine which is itself contained in many Allium species and is derived from the amino acid Cystein. Alliin dominates in garlic-type Allium species which includes Garlic (Allium sativum), Elephant Garlic (Allium ampeloprasum var. ampeloprasum), Rosy Garlic, Wild Leek (Allium ampeloprasum) and Sand Leek (Allium scorodoprasum).

Note how the glutamyl group is analogous to Methiine without the sulfur.



IsoAlliin is isomeric with Alliin; the only difference being in the position of the double bond between carbon atoms. Note how the glutamyl group is analogous to Methiine without the sulfur.

Ultimately, the specific flavour of all Allium species depends upon the ratios and amounts of these cystein sulfoxides. Very high levels of cystein sulfoxides are associated with a very hot taste (the thiosulfinates) which protect these plants against herbivores.

Alliin is the S-oxide of S-Allyl Cysteine which is itself contained in many Allium species and is derived from the amino acid Cystein. Alliin dominates in garlic-type Allium species which includes Garlic (Allium sativum), Elephant Garlic (Allium ampeloprasum var. ampeloprasum), Rosy Garlic, Wild Leek (Allium ampeloprasum) and Sand Leek (Allium scorodoprasum) whilst Methiine is dominant in Chives and Isoalliin is dominant in the 'onion-type alliums such as Garden Onion (Allium cepa), Chives (Allium schoenoprasum), Shallot and Garden Leek (Allium porrum). There is an enormous difference in the ratio of isoalliin between mild 'Spanish' onions and the extremely pungent 'dehydrator onion cultivars' which are bred to have a low moisture content (and double the dry-weight of Mild Onions) making them more suitable for dehydrating. Garlic (Allium sativum) contains more alliin than does the milder tasting Elephant Garlic (Allium ampeloprasum var. ampeloprasum) which is more on the 'leek' side of the family. Alliin and Isoalliin are rarely co-dominant, but equal amounts of alliin, isoalliin and Methiin are present in Ramson (Allium ursinum).

Methyl derivates, such as methiin, are more associated with allium species having a sharper and unpleasant odour and which are rarely eaten by man. Relatively low levels of methiin (<20%) are found in Allium species used as vegetables or medicinal plants such as Wild Leek (Allium ampeloprasum), Onion (Allium cepa), Chinese Chives (Allium tuberosum) and the non-natives Tree Onion (Allium proliferum) and Milk Onion (Allium galanthum).


Butenyl derivatives are rare but both butiin and S-1-butenylcystein sulfoxide are present in Honey Garlic (aka Sicilian Honey Garlic) (Nectaroscordum sicilum previously known as Allium sicilum) endowing upon the plant a strong gas-type odour when cut.


Pentenyl derivatives such as S-3-PentenylCystein Sulfoxide is found in Red Onion (Allium cepa var. tropaena)

Differences in the concentration ratios between the four flavour precursor compounds, methiin, propiin, alliin and isoalliin is very useful in determining the differing Allium species. This is called chemotaxonomy. However, the same plant grown under differing environmental conditions can lead to variations in the ratios and amounts of these precursors. Presumably Onions grown in Spain yield milder onions.

Many compounds of sulfur are notoriously unstable and great care is required in their proper identification; they can easily change into other moieties during the isolation process even during moderate heating. The usual method of gas chromatography, where volatile oils are heated and carried by a flow of helium gas into a glass column where they are deposited in layers can introduce artifacts.


  Allium roseum  ⇐ Global Aspect ⇒ Alliaceae  

Distribution
 family8Onion & Garlic family8Alliaceae

 BSBI maps
genus8Allium
Allium
(Onions)

ROSY GARLIC

Allium roseum

Onion & Garlic Family [Alliaceae]