Rhubarb

Relative of Chinese Rhubarb. Photo by H. Zell on Wikimedia Commons

Rheum palmatum

Common Name: Chinese Rhubarb.

Family: Polygonaceae.

Known Hazards: The leaves are poisonous. This report probably refers to high levels of oxalic acid found in the leaves. Perfectly safe in moderate quantities, oxalic acid can lock up certain . . . → Read More: Rhubarb

Cascara

Cascara Picture from Wikimedia Commons

Rhamnus purshianus

Common Name: Cascara Sagrada.

Family: Rhamnaceae.

Known Hazards: There is the suggestion that this species could be mildly poisonous.

Habitats: Rich bottom lands and sides of canyons, usually in coniferous forests.

Range: Western N. America - British Columbia to California.

Physical Characteristics . . . → Read More: Cascara

Buckthorn

Buckthorn Photo From US National Park Service invasive plants factsheet.

Rhamnus cathartica

Common Name: Common Buckthorn.

Family: Rhamnaceae.

Known Hazards: The fruit is purgative but not seriously poisonous. Other parts of the plant may also be poisonous.

Habitats: Fen peat, scrub, hedges, ash and oak woods, on calcareous often dry . . . → Read More: Buckthorn

Rehmannia

Rehmannia Photo by Shizhao http://commons.wikimedia.org/wiki/File:Rehmannia.JPG

Rehmannia glutinosa

Common Name: Chinese Foxglove.

Family: Gesneriaceae.

Synonyms: R. chinensis.

Habitats: Well-drained stony ground along roadsides and in woods. Mountain slopes and trail-sides from near sea level to 1100 metres.

Range: E. Asia - N. China, Korea.

Physical Characteristics

Rehmannia glutinosa is a . . . → Read More: Rehmannia

Lesser Celandine

Lesser Celandine by H. Zell on Wikimedia Commons

Ranunculus ficaria

Common Name: Lesser Celandine.

Family: Ranunculaceae.

Known Hazards: All parts of the plant are poisonous. The toxins are unstable and of low toxicity, they are easily destroyed by heat or by drying. The sap can cause irritation to the skin.

. . . → Read More: Lesser Celandine

Oak

Oak Photo by Jorchr http://commons.wikimedia.org/wiki/File:Svaneholm,_ek.jpg

Quercus robur

Common Name: Pedunculate Oak.

Family: Fagaceae.

Habitats: Often the dominant woodland tree, especially on clay soils and in the eastern half of Britain, but avoiding acid peat and shallow limestone soils.

Range: Europe, including Britain, from Scandanavia south and east to Spain, the . . . → Read More: Oak