POLYaONACE^ (buckwheat FAMILY.) 701 



Var. lieteraiitlia, Boiss. Some of the flowers (often in the 

 same receme), 4-merous, with flat akene, others 5-merous, with trique- 

 trous akene — Same range as last; also Aintab and Sof Dagh. 



7. POIuYGONVm, L. Knotweed. 



Flowers perfect. Perigonium 4-5-cleft or -parted, herbaceous or 

 petaloid, persistent, enclosing the fruit. Stamens 4-8, in two rows, 

 inserted at base of perigonium. Styles or stigmas 2-3. i\.kene trian- 

 gular or lenticular, crustaceous, with erect seed. Embryo accumbent 

 to angle of albumen, or curved and somewhat immersed, with leafy 

 cotyledons and superior radicle — Annual or perennial herbs or shrubs, 

 with the base of the petiole expanded into a membranous, tubular 

 sheath (ockrece), and membranous, interfloral bracts (ochreoles). 



(a) Tip of a flowering branch of a Polygonum, showing the ochrea3, leaves, and spikes 

 of flowers. (&) A single flower, showing the 4 lobes of perigonium with stamens inserted 

 at their base, and the free ovary with two styles, connate at base, (c) Vertical section of 

 ovary, showing the erect ovule, (d) Vertical section of seed, showing the lateral embryo. 



* S2nl:e 1, at ti^) of simple stem. Styles 3,' free^ with small stigmas. 



Stamens 5-8. Oclirem oblique, not ciliate. 



1 P. Bistorta. 



* * Stems usually drancJdng, spikes at end of hrandies. Styles 3-3, m,ore 

 or less connate. Stamens 8-4, loith alternate scales. Ochrem cylindrical, 



usually ciliate. 



t Perennials. ' Flowers in 'i pjentandrous^ in 3 hexandrous. 



2 P. amphibium, 3 serrulatum. 



