Peucedanum galbanum
Encyclopedia
Peucedanum galbanum, better known as the Blister Bush, is a plant best known for its ability to cause painful blistering after contact. The plant is in the family Apiaceae, subfamily Apioideae. Although it is in the same family as edible plants such as the carrot
and herbs such as fennel
and dill
, it is not edible and touching it can cause severe blistering particularly if the irritant chemicals are exposed to sunlight.
or celery
. The flower head has a very green and slightly yellow appearance and is made up of many tiny yellow flowers that occur in large green compound umbels. The umbel gives off flat winged seeds.
and western Cape Fold Belt
region of the Western Cape in South Africa. It is usually found at medium- to high-altitudes in partially shady and damp areas but will also grow at lower altitudes and in areas of direct sunshine. The plant grows in the winter rainfall areas, which are relatively frost-free and have well-drained soils.
, xanthotoxin and bergapten
that causes a phototoxic
reaction resulting in blistering two or three days after exposure. The moment of exposure is innocuous, without any untoward sensations to the unwary. Exposure of the affected skin to ultra violet light, such as contained in sunlight, triggers the effects of the plant's toxins, leading to severe itching and blistering. The welts and resulting blisters can be as small as the size of a coin to covering as much exposed skin as came into contact with the plant. Where more than 5% of the body is afflicted, the scarring can be a serious matter. Washing the affected area immediately after exposure may help but preventing any further exposure to ultra violet light such as the sun or many artificial light sources will reduce and /or eliminate blistering.
If untreated the welt should stop itching and weeping after the first five to seven days. Once this has happened, it should be left exposed to allow the affected area to breathe. Blisters sometimes subside into a tender scab or scar that can take many months to disappear altogether.
Carrot
The carrot is a root vegetable, usually orange in colour, though purple, red, white, and yellow varieties exist. It has a crisp texture when fresh...
and herbs such as fennel
Fennel
Fennel is a plant species in the genus Foeniculum . It is a member of the family Apiaceae . It is a hardy, perennial, umbelliferous herb, with yellow flowers and feathery leaves...
and dill
Dill
Dill is a perennial herb. It is the sole species of the genus Anethum, though classified by some botanists in a related genus as Peucedanum graveolens C.B.Clarke.-Growth:...
, it is not edible and touching it can cause severe blistering particularly if the irritant chemicals are exposed to sunlight.
Appearance
The Blister Bush's leaves look like flat-leaved parsleyParsley
Parsley is a species of Petroselinum in the family Apiaceae, native to the central Mediterranean region , naturalized elsewhere in Europe, and widely cultivated as an herb, a spice and a vegetable.- Description :Garden parsley is a bright green hairless biennial herbaceous plant in temperate...
or celery
Celery
Apium graveolens is a plant species in the family Apiaceae commonly known as celery or celeriac , depending on whether the petioles or roots are eaten: celery refers to the former and celeriac to the latter. Apium graveolens grows to 1 m tall...
. The flower head has a very green and slightly yellow appearance and is made up of many tiny yellow flowers that occur in large green compound umbels. The umbel gives off flat winged seeds.
Distribution and habitat
The Blister bush is native to the Table MountainTable Mountain
Table Mountain is a flat-topped mountain forming a prominent landmark overlooking the city of Cape Town in South Africa, and is featured in the flag of Cape Town and other local government insignia. It is a significant tourist attraction, with many visitors using the cableway or hiking to the top...
and western Cape Fold Belt
Cape Fold Belt
The Cape Fold Belt is the folded sedimentary sequence of rocks in the southwestern corner of South Africa. It is related to the Ventana Mountains near Bahía Blanca in Argentina...
region of the Western Cape in South Africa. It is usually found at medium- to high-altitudes in partially shady and damp areas but will also grow at lower altitudes and in areas of direct sunshine. The plant grows in the winter rainfall areas, which are relatively frost-free and have well-drained soils.
Effects on the body
The surface of the plant is covered in a mix of chemicals including psoralenPsoralen
Psoralen is the parent compound in a family of natural products known as furocoumarins. It is structurally related to coumarin by the addition of a fused furan ring, and may be considered as a derivative of umbelliferone...
, xanthotoxin and bergapten
Bergapten
Bergapten is a psoralen found in bergamot essential oil, in other citrus essential oils, and in grapefruit juice. It is the chemical in bergamot oil that causes phototoxicity. Bergapten-free bergamot essential oil or synthetics are now used in perfumery....
that causes a phototoxic
Phototoxic
Phototoxicity is a chemically induced skin irritation requiring light . The skin response resembles an exaggerated sunburn. The involved chemical may enter into the skin by topical administration or it may reach the skin via systemic circulation following ingestion or parenteral administration...
reaction resulting in blistering two or three days after exposure. The moment of exposure is innocuous, without any untoward sensations to the unwary. Exposure of the affected skin to ultra violet light, such as contained in sunlight, triggers the effects of the plant's toxins, leading to severe itching and blistering. The welts and resulting blisters can be as small as the size of a coin to covering as much exposed skin as came into contact with the plant. Where more than 5% of the body is afflicted, the scarring can be a serious matter. Washing the affected area immediately after exposure may help but preventing any further exposure to ultra violet light such as the sun or many artificial light sources will reduce and /or eliminate blistering.
Treatment
Preventing the blister from forming is the best way to deal with the affliction. Apart from covering the area and preventing any exposure to sunlight, it is useful to directly apply suntan lotion as well, employing as high as possible a screen factor such as factor 50 or 100. Reapply the lotion as soon as the itching starts again. While the red itchy welt is best treated before the blister appears, all is not lost if you are late. Direct application of the spray-on types of sunscreen, particularly those high in alcohol, tends to both dry the welt and reduce the irritation with immediate effect. If sun tan lotion is applied soon enough, the process can be interrupted in its entirety.If untreated the welt should stop itching and weeping after the first five to seven days. Once this has happened, it should be left exposed to allow the affected area to breathe. Blisters sometimes subside into a tender scab or scar that can take many months to disappear altogether.
Other references
- Germishuizen, G. & Meyer, N.L. (eds). 2003. Plants of southern Africa : an annotated checklist. Strelitzia 14. National Botanical Institute, Pretoria.
- Goldblatt, P. & Manning , J. 2000. Cape plants. A conspectus of the Cape flora of South Africa. Strelitzia 9. National Botanical Institute, Cape Town and Missouri Botanical Garden.