188 OCTANDRIA TKIGYNIA. [CL. VIII. 



TRIGYNIA. 

 10. POLY/GONUM. BUCK- WHEAT. 



Calyx inferior, turbinate, coloured, deeply divided into five 

 egg-shaped, permanent segments. Corolla none. Filaments 

 variable in number, awl-shaped, very short ; anthers roundish. 

 Germen superior, roundish, triangular, or compressed. Styles 

 generally three, in some species two, thread-shaped, very short ; 

 stigmas simple. Seed solitary, triangular, or compressed, 

 pointed. Named from polys, many, and gonu, a knee or joint. 



216. 



1. P. Bistorta. Great Bistort. Snake-weed. Stem simple, bearing 

 a single spike ; leaves egg-shaped, waved, running down into the 



foot-stalks. Stems erect, about two feet high, leafy : flowers 



rose-coloured. Perennial : flowers in June : grows in pastures and 

 meadows: frequent. Eng. Bot. vol. viii. pi. 509. Eng. FL vol. ii, 

 p. 236. 607. 



2. P. mmparum. Alpine Bistort. Stem simple, bearing a single 



spike ; leaves lance-shaped, revolute at the margin. Stem from 



three to eight inches high, erect, leafy: flowers pale-red. Peren- 

 nial : flowers in June and July : grows in mountain pastures : fre- 

 quent. Eng. Bot. vol. x. pi. 669. Eng. FL vol. ii. p. 237. 608. 



3. P. aviculdre. Common Knot-grass. Flowers axillar ; leaves 



lance-shaped, rough-edged ; stem procumbent. Stems several, 



decumbent, spreading in all directions : leaves alternate, stalked : 

 flowers two or three together, reddish. Annual : flowers in summer 

 and autumn : grows in fields, waste places, byroads, &c.: common. 

 Eng. Bot. vol. xviii. pi. 1252. Eng. Fl. vol.ii. p. 238. 609. 



4. P. Roberti. Robert' s Knot-grass. Flowers axillar; leaves lance- 

 shaped, distant ; fruit shorter than the calyx, smooth. A large 



straggling species, appearing intermediate between the preceding 

 and following. Annual : flowers in August and September : grows 

 on the sea-shore : common. Eng. Bot. Suppl. pi. 2805. Brit. Fl. 

 4th ed. p. 163. 610. 



5. P.maritimum. Sea -side Knot-grass. Flowers axillar ; leaves 

 lance-shaped, fleshy, glaucous, crowded ; fruit longer than the 

 calyx, smooth. Annual : flowers in August and September : grows 

 in the south of England, and the Channel Islands, on the sea-shore. 

 Eng. Bot. Suppl. pi. 2804. Brit. FL 4th ed. p. 164. 611. 



6. P. Fagopy'rum. Buck-wheat. Branks. Leaves between heart- 

 shaped and arrow-shaped ; stem nearly erect, without prickles; 



angles of the seeds equal. Clusters many-flowered, panicled, 



spreading : flowers variegated with red, green, and white : the 

 seeds furnish a nutritious meal, -which in some parts of England is 

 made into thin cakes called crumpets. It is usual for farmers to 

 sow a crop of buck- wheat, and plough it down for manure. An- 

 nual : flowers in July and August : grows in cultivated fields, but 

 is not indigenous. Eng. Bot. vol. xv. pi. 1044. Eng. Fl. vol. ii. p. 

 239. 612. 



7. P. Convolvulus. Black Bindweed. Leaves between heart- 

 shaped and arrow-shaped ; stem twining, angular; segments of the 

 calyx bluntly keeled ; fruit striated with minute points. Stem 



