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ALDER BUCKTHORN

Frangula alnus

(Formerly: Rhamnus frangula)
Buckthorn Family [Rhamnaceae]

Flowers:
month8jun month8june month8jul month8july

Berries: berryZpossible        berryZgreen berryZyellow berryZorange berryZred  (poisonous)
berry8jun berry8june berry8jul berry8july berry8aug berry8sep berry8sept

category
category8Shrubs
category
category8Deciduous
category
category8Broadleaf
status
statusZnative
flower
flower8white
inner
inner8green
morph
morph8actino
petals
petalsZ5
stem
stem8round
toxicity
toxicityZmedium
sex
sexZbisexual

13th July 2011, Linnyshaw Rly Line, Blackleach, Walkden. Photo: © RWD
A deciduous shrub between 2m - 6m tall which grows in damp woods, scrub and fens mainly in acid soils in the south of the UK. A more open shrub less dense than is Buckthorn.


13th July 2011, Linnyshaw Rly Line, Blackleach, Walkden. Photo: © RWD
Leaves alternate or sometimes accidentally in opposite pairs. They are without teeth (entire margin) and ovate in shap and slightly downy on the prominently grooved veins.


13th July 2011, Linnyshaw Rly Line, Blackleach, Walkden. Photo: © RWD
Berries, 6-10mmφ, start appearing in June, green at first, going through red, dark-purple and finally to black when ripe. They contain 2-3 pale brown seeds 5mm across. Berries dispersed by birds which eat the fruits.


13th July 2011, Linnyshaw Rly Line, Blackleach, Walkden. Photo: © RWD
Hermaphroditic flowers appear in the axils of the leaf stalks. Leaves somewhat similar to those of Dogwood such as White Dogwood with one major difference: the veins fan out to the edges of the leaf rather than recurve back into the leaf.


13th July 2011, Linnyshaw Rly Line, Blackleach, Walkden. Photo: © RWD
Stems reddish-brown.


13th July 2011, Linnyshaw Rly Line, Blackleach, Walkden. Photo: © RWD
Flowers in 2-6 axillary cymes. Unopened flower buds on short stalks look like Kermit the frog with mouth tight shut. The green sepal tube splits half-way along to become five thick equilateral-triangular white petals with rounded tip splayed open. The reddish-brown stems are slightly hairy.


13th July 2011, Linnyshaw Rly Line, Blackleach, Walkden. Photo: © RWD
The hermaphroditic flower with male and female parts. Green pistil in centre formed from five fused carpels.


13th July 2011, Linnyshaw Rly Line, Blackleach, Walkden. Photo: © RWD
Sepal tube and petals part of same structure.


13th July 2011, Linnyshaw Rly Line, Blackleach, Walkden. Photo: © RWD
Five petals, five stamens with anthers inside some king of folded cowl structure.


13th July 2011, Linnyshaw Rly Line, Blackleach, Walkden. Photo: © RWD
Leaves unusual - they look like they sit on top of the leaf stem, which is grooved for a short distance from the leaf.


13th July 2011, Linnyshaw Rly Line, Blackleach, Walkden. Photo: © RWD
In the centre is a bud for a new stem, which are hairy and look damaged. Note how the leaves seem to be in two separate halves sitting atop the leaf stalk.


Not to be semantically confused with : Fragaria [which is the Genus containing the various Strawberrys]

Some similarities to : Buckthorn (Rhamnus cathartica) which is also poisonous but has only four petals which are narrower and longer in shape than the stubby triangular ones of Alder Buckthorn. Alder Buckthorn also lacks the thorns of Buckthorn.

Slight resemblance to : The leaves look similar to those of Dogwood (Cornus sanguinea) and has been mistakenly called Dogwood in the past, but the veins are very different in the path they take through the leaves.

No relation to : Alder [trees with similar names] nor to Buckwheat (Fagopyrum esculentum) nor yo Buck's-Beard (Aruncus dioicus) nor to Sea-Buckthorn (Hippophae rhamnoides) a sea-side shrub.

Some sources leave Alder Buckthorn in the Rhamnus Genus for historical reasons (where it lies along with Buckthorn (Sloe) itself), indeed, both are in the Rhamnaceae family, but a separate Frangula Genus for Alder Buckthorn seems to be widely accepted, being also supported by recent genetic data.

It's name is somewhat of a misnomer for it lacks thorns, but does belong to the same family as Buckthorn (not to be confused with Blackthorn (Prunus spinosa), of sloe fame) which does. However, it has five petals whereas Buckthorn has but four, and its flowers are hermaphroditic (whereas in Buckthorn they are dioecious with mame and female flowers on separate plants).

Some sources say that the shrub has dioecious flowers, with male and female flowers on separate plants, whilst many other sources claim it is bisexual (aka hermaphrodite) where each flower has both male and female parts. Maybe the shrub is a bit ambivalent on this matter. Whatever, the flowers in the above photos of the plant are hermaphroditic.

Charcoal made from the wood of Alder Buckthorn was especially prized for its suitability for making gunpowder and fuses for dynamite because of its even burn-rate.

Native to the UK it originates from Scotland. It obtains its scientific name alnus meaning 'aldes' from because it likes to grow together with Alders in on damp sites.

The Genus name Frangula refers to the brittle nature of the wood. Cultivars are made, Rhamnus frangula 'variegata', 'Tallhedge' for hedging and 'Aslenifolia' with extremely long and narrow leaves, longer even than those of Chinese Weeping Willow.

The bark yields a yellow dye whilst the un-ripe berries produce a green dye which has been used for dying wool. Both berries and bark are poisonous containing a glycosides of poisonous anthraquinones which are purgative, as are those of Purging Buckthorn (Frangula cathartica). The two differently-coloured dyes are derived from these anthraquinones.

ANTHRAQUINONES



Alder Buckthorn contains the anthraquinones Aloe-emodin (in the callus but not the bark) and Emodin (aka Frangula-Emodin / Rheum-Emodin).

 Chrysophanol and Emodin are orange.

 AloeEmodin is orange-yellow



EMODIN GLYCOSIDES


The mono-glycosides of Emodin, called Frangulin A (Emodin-6-O-Rhamnoside) and Frangulin B (Emodin-6_O-Apioside) occur in the bark, the mixture of the two together are known as 'Frangulosid' or 'Frangulin'.

 Frangulin is a component of Yellow Lake Pigment (as used by the painters such as Vermeer) which is made from Frangula species. These Lake pigments are very prone to fading by the exposure to light (especially the UV component) over time, and particularly if they are used with chalk rather than aluminium hydroxide as the substrate/absorbent.

Certain anthraquinones, for example Lucidine, can form DNA-adducts with the DNA bases Guanine or Adenine on DNA strands, which result in malfunctional DNA and perhaps cancer.


DIANTHRONES


Within the Frangula genus the bianthrones Emodin­Dianthrone, Chrysophanol­Dianthrone and the mixed Chrysophanol­Emodin­Dianthrone are found. The fresh callus predominantly contains the glycosides of Chrysophanol­Dianthrone and Chrysophanol­Physcion­Dianthrone.


  Frangula alnus  ⇐ Global Aspect ⇒ Rhamnaceae  

Distribution
 family8Buckthorn family8Rhamnaceae

 BSBI maps
genus8Frangula
Frangula
(Alder Buckthorn)

ALDER BUCKTHORN

Frangula alnus

(Formerly: Rhamnus frangula)
Buckthorn Family [Rhamnaceae]