Lookee-Likees : The red berries and its climbing tendencies are similar to Black Bryony, but unlike that, it twines anti-clockwise. The leaves of Black Bryony are shaped like the Ace of Spades, whereas those of White Bryony have large long lobes. The tendrils, which also come from the leaf axils (like the flowers) are used for clinging to branches of other plants are simple, unbranched.
Uniquely identifiable characteristics : there is no other plant quite like this.
Distinguishing Feature : White Bryony has only five petals; Black Bryony six.
No relation to : Black Bryony [a plant with similar name] which belongs to the Yam Family, whereas White Bryony belongs to the Marrow Family.
The flowers themselves bear some resemblance to those of Virgin's-Bower (Clematis flammula) in that they are covered in short hairs (but in the case of White Bryony on both sides rather than only on the lower surface on Virgin's-Bower), and curve backwards but they have five petals rather than four. Other than the flowers, the plants are totally different.
The lesser-well-known alternative name for White Bryony is 'Red Bryony' and is named after the red berries it displays after flowering, as opposed to the black berries of Black Bryonys'.
White Bryony contains the bitter and toxic principle
bryonin (also known as bryonidin or bryonol) a glycoside responsible for the plants purgative effect. It can cause convulsions in horses. The roots can be mistaken for parsnips or turnips. It also contains the alkaloid
bryonicine or bryonidine and
cucurbitacins which are tri-terpenoids.
The flowers are slightly fuzzy hairy and creamy white with green veins, giving the overall appearance as a greenish flower. The plant is dioecious, meaning that male and female flowers are on separate plants. Male flowers, at 12-18mm across, are larger than the female flowrers at only 10-12mm across. Male has 3 stamens with deep-yellow anthers (although some specimens shown above seem to have more than 3), the female 1 style split into 3 green hairy discoidal stigmas near the top. It grows from a thick tuberoua rootstock.
There are 8 species of White Bryony with a presence in Europe (but seemingly only one in the UK). In some parts of the world Bryonia alba is confusingly also known as White Bryony, which differs slightly from the UK White Bryony Bryonia dioica in that Bryonia alba may have male and female flowers on the same plant. The plants is perennial and fairly common, occurring in hedges and in scrub, usually on well-drained alkaline soils in England, but mostly avoiding most of the North and the South-West. It is native, but introduced elsewhere.
The berries, which are greenish at first, turn orange then red. All parts of this plant are highly poisonous, especially the red berries and the roots. Just 40 berries are lethal for adults, only 15 for children.. The red berries also accumulate a toxic protein called
Brydiofin, with a molecular weight of 66 kiloDaltons, which is far too big to draw on here. Cucurbitacins bind to microtubules within cells preventing cell division and are therefore cytotoxic; also a skin irritant, and ingestion causes nausea, vomiting, diarrhoea, strong colic with spasms, tachycardia, and finally respiratory arrest. Because Cucurbaticins inhibit cell division they therefore have anti-tumour activity. Although they have in the distant past been used medicinally, they are too toxic and the effects too drastic to be used in modern times.
Cucurbaticin B is a triterpene steroid, and is one of the most bitter and acrid substances known; a property utilised by the plant to defend itself against being eaten by herbivores. Cucurbaticins are stored as glycosides in plant cell vacuoles and only upon wounding is the toxic Cucurbaticin freed of the sugar molecules by the action of an enzyme, β-glucosidase. Contact with the sap from plants containing cucurbaticins results in erythrema, painful inflammation and blister formation. The cucurbaticins from Bryonia species are therefore, somewhat surprisingly, used in creams and ointments to alleviate rheumatism and muscle pain.
Related to the Cucurbaticins (of which Cucurbaticin B is just one) are the Arvenins, of which four are know, Arvenin I, Arvenin II, Arvenin III and Arvenin IV. Shown is just one, Arvenin I. Arvenin I is just Cucurbaticin B with a glycoside attached. The Arvenins are glucopyranosides. Possibly all are present to some extent in White Bryony and some other members of the Marrow Family. In the vegetables Cucumber and Marrow most of the toxic Cucurbaticins have been bred out, and are mostly safe to eat. The same poisons are also in Scarlet Pimpernel,
Begonia, New-Zealand Flax (Agave Family),
Garden Cress and
Wild Candytuft, as well as numerous other non-native plants.
Other sources name seven triterpene glycosides (
Bryoniosides A-G) occur in this plant, as well as the two more triterpene glycosides: