COMMON TOADFLAX

Linaria vulgaris

Plantain Family [Plantaginaceae]  
Formerly in: Figwort & Foxglove Family [Scrophulariaceae]

month8jun month8june month8jul month8july month8Aug month8sep month8sept month8Oct

status
statusZnative
flower
flower8bicolour
flower
flower8yellow
inner
inner8orange
morph
morph8zygo
petals
petalsZ2
type
typeZspurred
stem
stem8round

30th July 2004, anywhere Photo: © RWD
At heights up to 90cm it is usually shorter than Purple Toadflax. A spire of large yellow flowers tops every leafy stem.


16th Aug 2005, somewhere Photo: © RWD
The leaves are narrow and linear and all around the stem; very similar to those of Purple Toadflax.


30th July 2004, anywhere Photo: © RWD
The flowers are usually a pale yellow with two deeper yellow (sometimes nearly orange) bulges near the middle.


16th Aug 2005, somewhere Photo: © RWD
The flowers have zygomorphic symmetry, and a long greenish-yellow curved spur at the bottom.


6th July 2005, everywhere Photo: © RWD


6th July 2005, everywhere Photo: © RWD
There are two pale yellow cowls at the top, two central deeper yellow bulges, and a lower lip that is nicked into three parts.


16th Aug 2005, somewhere Photo: © RWD
At 18-35mm long, the flowers are much larger than those of Purple Toadflax at just 7-15mm (and Purple Toadflax has purple flowers)


16th Aug 2005, somewhere Photo: © RWD


10th July 2014, railway retaining wall, Blackburn, Lancs. Photo: © RWD
A much paler version exists, and is growing in profusion high up on a vertical retaining wall of the railway viaduct through Blackburn.


10th July 2014, railway retaining wall, Blackburn, Lancs. Photo: © RWD
The long spur is in evidence from a low perspective.


No relation to : Flaxes such as Cultivated Flax (Linum usitatissimum) [plants with similar names belonging to differing families].

Hybridizes with : Pale Toadflax (Linaria repens) to produce Linaria × sepium which has pale yellow flowers with violet veins.

Common Toadflax (sometimes called Yellow Toadflax) is by far and away the most common toadflax in the UK. It contains the Quinazolene alkaloids Vasicine (aka Peganine), Vascinone, DeOxyVascinone (Vasicine without the -OH group), and 1,2,3,9-tetraHydroPyrrolo(2,1)Quinazolin-1-Carboxylic Acid. It also contains Syringin and the lignan glycoside Liriodendrin, for which the author can find two differing structural formulae...

Native to Eurasia, Common Toadflax may have been introduced to the UK as a garden plant. It is a short-lived perennial and produces extensive, creeping rhizomatous roots, growing in dense patches. Because of this propensity to spread, in some parts of the world it is classed as an invasive species. Habitat includes grassy banks, road verges and waste places.

The seeds form in a brown and two-celled capsule which contains many very small, circular flattish seeds with a central bulge having many small bumps, a little like a flying saucer sweet, but far smaller. They can remain viable in the soil for 10 years.

A LIGNAN


Liriodendrin is a dimeric furo-furanoid lignan glycoside. One website (probably wrongly) shows it not with two glycosides, but with four). It is also found in Wild Madder and the Tulip Tree (Liriodendron tulipfera) from which it derives its name. It may have applications as a suppressor of Calcium chloride-induced arrhythimas due to its calcium-channel antagonistic effect in nerve cells.

QUINAZOLINES


These two alkaloids are Pyrroloquinazoline alkaloids, both found in Common Toadflax along with several similar derivatives. Peganine, aka Vasicine, was though to have a bronchodilatory effect comparable to that of Theophylline, but it has now been shown that this is false, and exhibits instead the opposite bronchoconstrictory activity! Vasicinone is the 9-ketone and the auto-oxidation product of Vasicine. These alkaloids are known uterotonic, oxytocic and abortifacients. They are also active principles present in the Harmala plants, which includes Syrian Rue (Peganum harmala), although chemically they are very different from Harmine, Harmaline and Harmalol which have the pentagonal ring in the centre.

Quinazoline itself and upon which the above substances are based, is an alkaloid with two nitrogen atoms, shown here only for the purpose of illustration; it has no quoted presence in Common Toadflax. Quinazoline is isomeric with Quinoxaline, Phthalazine and Cinnoline which have the two nitrogen atoms in differing positions on the same ring. There is no reported presence of Quinazoline in Common Toadflax.


  Linaria vulgaris  ⇐ Global Aspect ⇒ Plantaginaceae  

Distribution
family8Plantain family8Plantaginaceae

 BSBI maps
genus8Linaria
Linaria
(Toadflaxes)

COMMON TOADFLAX

Linaria vulgaris

Plantain Family [Plantaginaceae]  
Formerly in: Figwort & Foxglove Family [Scrophulariaceae]

WildFlowerFinder Homepage