Polygonaceae and Loranthaceae- Introduction

Polygonaceae

(Buckwheat or smartweed family)

Plants of this family are mostly herbs, some shrubs (Polygonum hydropiper) or climbers (Antigonon leptopus) and only rarely trees (Triplaris, Coccoloba uvifera). Often they have swollen nodes; sometimes geniculate i.e. bent like a knee.

                                                               represented by about 40 genera and 1000 species, Polygonaceae are distributed chiefly in north temperate regions, and a few also in tropical, arctic and southern hemisphere. About 10 genera and over 100 species have been reported from India. 

Selected Indian genera are: 

• Antigonon, 
• Coccoloba, 
• Fagopyrum, 
• Polygonum, 
• Rheum and 
• Rumex. 
• Polygonum orientale an ornamental plant is commonly known as "kiss-me-over-the-gate".

Economic Importance

Except for some medicinal and ornamental value, the family is not of much importance. Some of its economic aspects are-

Ornamental plants:

• Antigonon leptopus (climber with bright pink or white flowers)
• Muehlenbeckia platyclada syn. Coccolaba platyclada
• Polygonum alpinum
• P. glabrum (pink flowers)
• P. orientale
• P. paniculateum
• P. blebejum (pink flowers)

Medicinal plants of the family:

• Polygonum aviculare, used against diabetes and rheumatism,
• Rheum modi and R. officinale roots and rhizome yield the drug 'rhubarb' used as a laxative, purgative and stomach tonic,
• Rumex acetosella leaves are said to be effective in tumours and cancer,
• Rumex acetosa is used in bronchial diseases and also as a blood purifier,
• Polygonum glabrum seeds are used in leucorrhoea.

Edible plants:

• Leaves of Oxyria digyna, Rumex acetosella and R. acetone (sorrel) are eaten as vegetable or salad.
• Fagopyrum esculentum (buckwheat or 'kuttu') seeds are edible because they are rich source of protein. Its flowers are very rich in honey. F. tataricum (buckwheat) is also used for similar purposes.
• Rumex hastatus leaves are used as condiment.

Dye:

Polygonum tinctorium is the source of a blue dye.

Loranthaceae

(Mistletoe family)

Plants of this family are mostly semiparasitic herbs or small shrubs attached to their hosts by sucking haustoria; rarely erect, terrestrial trees (eg. Nuytsia) Usually aerial parasitic habit; cup-shaped receptacle; inferior ovary; ovules not differentiated from the placenta.

               Family is represented by about 36 genera and 1300 species and distributed in both tropical and temperate regions. About 10 genera and over 52 species have been reported from India. 

Some largely represented genera are: 

• Loranthus, 
• Phoradendron, 
• Struthanthus, 
• Viscum, 
• Dendrophthora and 
• Psittacanthus. 

Selected Indian genera are: 

• Dendrophthoe, 
• Loranthus and 
• Viscum.

Economic Importance

Plants of Loranthaceae are of no specific economic importance. Only Viscum album (mistletoe) and some species of Phoradendron (eg. P. flavescens) are of ornamental value and used for decorative purposes, specially at Christmas time.