Citation: L., Sp. Pl. 359 (1753).

Derivation: Greek poly, many; gonia, a knee; the stems have many nodes.

Synonymy: Not Applicable

Common name: None

Description:
Herbs, erect, prostrate or climbing; leaves linear to ovate; stipular sheath usually truncate.

Flowers small, in axillary or bracteate clusters, often forming narrow panicles, usually bisexual; perianth-segments usually 5, almost equal; stamens 5-8; styles 2 or 3, sometimes united towards the base, with entire terminal stigmas.

Nut enclosed in the persistent perianth; embryo lateral, curved.

Distribution:  About 300 species; cosmopolitan.

Biology: No text

Key to Species:

1. Young stems hairy
2. Stems prostrate
3. Inflorescence lax; stem hairs reflexed	P. strigosum 12.
3. Inflorescence dense; stem hairs, when present, ascending or spreading
4. Inflorescence capitate	P. capitatum 3.
4. Inflorescence elongate	P. prostratum 10.
2. Stems erect
5. Stipules dilated and green at the top (SL region)	P. orientale 7.
5. Stipules closely ensheathing and scarious at the top (LE region)	P. attenuatum 1.
1. Stems glabrous
6. Climber; leaves sagittate	P. convolvulus 4.
6. Prostrate or erect; leaves with cuneate or obtuse base
7. Flowers in clusters in the axils of scarcely reduced leaves; plant usually prostrate
8. Leaves 1-veined, linear-spathulate; nut shining	P. plebeium 9.
8. Leaves with several prominent lateral nerves below, more or less elliptic; nut dull	P. aviculare 2.
7. Flowers in dense or interrupted spikes or racemes; plant erect
9. Stipules ciliate; leaves subsessile	P. salicifolium 11.
9. Stipules entire or lacerate, not ciliate; leaves petiolate
10. Inflorescence very interrupted, merging gradually into the leafy part of the branches; largest laminas rarely exceeding c. 5 cm	P. patulum 8.
10. Inflorescence of clearly demarcated and usually compact racemes or spikes; larger leaves usually much exceeding c. 5 cm
11. Veins of the leaves scabrous below	P. lapathifolium 6.
11. Veins of the leaves glabrous-	P. glabrum 5.

Author: Not yet available