58 POLYGONACEAE 



7. Polygonum erectum L. Erect Knotweed. Fig. 1449. 



Polygonum erectum L. Sp. PI. 363. 1753. 



Annual with glabrous yellowish green foliage, the stem erect or ascending, 2-9 dm. high, 

 simple to much branched, strongly striate. Leaves elliptic-lanceolate, oval or obovate, 1-6 cm. 

 long, obtuse or acutish at apex, narrowed at base to a short petiole ; stipule-sheaths prominent, 

 united only near the base; axillary clusters mostly 1-2-flowered ; calyx 3 mm. long, greenish 

 yellow ; stamens 6 or sometimes 5 ; achenes ovoid, 3-angled, 2-3 mm. long, closely invested by 

 the calyx-lobes or the tip slightly protruding. 



Dry or moist soil, Upper Sonoran and Arid Transition Zones; eastern Oregon, near Lakeview, east to Idaho, 

 Utah, New Mexico, and the Atlantic States. Type locality: Philadelphia. June-Sept. 



8. Polygonum ramosissimum Michx. Yellow-flowered or Bush Knotweed. 



Fig. 1450. 



Polygonum ramosissimum Michx. Fl. Bor. Amer. 1: 237. 1803. 



Annual with glabrous usually yellowish green foliage, the stems erect or ascending, often 

 much branched, slender and usually rigid, 1-10 dm. high. Leaves lanceolate, acute at both ends, 

 2-5 cm. long; stipule-sheaths silvery, becoming deeply lacerate; axillary clusters several- 

 flowered; pedicels exserted ; calyx-lobes 5 or 6, yellow or with yellowish margins, 2.5-3 mm. 

 long; stamens 3-6; achene 3-angled, ovoid, included, black, smooth and shining. 



Dry plains and hills, Upper Sonoran and Arid Transition Zones; eastern Washington to Nevada, southern 

 California,, Texas, and the Atlantic States. Type locality: "In regione Illinoense. July-Sept. 



9. Polygonum majus (Meisn.) Piper. Palouse Knotweed. Fig. 1451. 



Polygonum coarctatum var. majus Meisn. in DC. Prod. 14: 101. 1856. 

 Polygonum majus Piper in Piper & Beattie, Fl. Palouse Reg. 63. 1901. 



Annual, the stems erect, 15-35 cm. high, usually much branched, slender and wiry, incon- 

 spicuously striate. Leaves linear-lanceolate, 2-6 cm. long, stipule-sheaths 15-20 mm. long; 

 flowers remote, in elongated spikes, subtended by short subulate bracts; calyx campanulate, 

 the lobes 4-5 mm. long, white with a simple green midvein; styles 3-cleft to the middle; achenes 

 reflexed, 3-angled, 3-3.5 mm. long, acuminate, black, smooth and shining. 



Sterile stony ground, Arid Transition Zone; Chelan County, eastern Washington, to Klamath County, 

 Oregon, east to Idaho. Type locality: along the Columbia, eastern Washington. Collected by Douglas. May-July. 



10. Polygonum Douglasii Greene. Douglas' Knotweed. Fig. 1452. 



Polygonum Douglasii Greene, Bull. Calif. Acad. 1: 125. 1885. 

 Polygonum exile Eastw. Proc. Calif. Acad. III. Bot. 2: 286. 1902. 



Annual, pale green and somewhat glaucous, the stems erect, slender, 2-5 dm. high, usually 

 sparingly branched, glabrous or somewhat scabrous about the nodes, terete or slightly ridged. 

 Leaves oblong to narrowly lanceolate, 1-5 cm. long, 2-8 mm. wide, obtuse to acute, sessile or 

 nearly so, thin and plane on the margins, revolute, the articulation with the sheath conspicuous, 

 stipules at length lacerate, the sheathing portion very short; flowers drooping, 1-3 in a cluster, 

 borne in all but the lowest axils ; pedicels 2-3 mm. long, reflexed ; calyx greenish, 3-4 mm. long, 

 the lobes oblong, with white or roseate margins; stamens 8; styles very short, 3-parted to the 

 base ; achene 3-angled. included, oblong to oblong-ovoid, black, smooth and shining. 



Rocky or sandy soils, Transition and Boreal Zones; British Columbia to the mountains of southern Cali- 

 fornia, east to the Rocky Mountains, and locally to the north Atlantic States. Type locality: not designated. 

 June-Sept. 



Polygonum Douglasii var. latifolium (Engelm.) Greene, Bull. Calif. Acad. 1: 125. 1885 (P. montanum 

 (Small) Greene; P. Howellii Greene.) Stems stouter, simple or sparingly branched. Leaves oblong or oblance- 

 olate, 10-45 mm. long; flowers more crowded; the bracts linear-subulate, the lower fohaceous. Olympic and 

 Cascade Mountains, south to the mountains of northern California. Usually at higher elevations than the typical 



species. 



11. Polygonum Austiniae Greene. Austin's Knotweed. Fig. 1453. 



Polygonum Austiniae Greene, Bull. Calif. Acad. 1: 212. 1885. 



Polygonum Douglasii var. Austiniae Jones, Contr. West. Bot. No. 12: 75. 1908. 



Erect annual, 6-15 cm. high, branched from the base. Leaves ovate, elliptic-ovate, or ovate- 

 lanceolate, 5-12 mm. long, acute at apex, basal narrowed to a petiole, cauline sessile, uppermost 

 reduced to bracts ; flowers in all but the very lowest axils, solitary or in pairs, drooping ; calyx 

 2-2.5 mm. long, the lobes with green midrib and white margins; achene 2.5-3 mm. long, black, 

 smooth and shining. 



Dry ridges, mainly Arid Transition Zone; Wheeler County, eastern Oregon, to Modoc County, California, 

 east to southern Idaho. Type locality: sagebrush plains, Modoc County, California. June-Aug. 



12. Polygonum minimum S. Wats. Leafy Dwarf Knotweed. Fig. 1454. 



Polygonum minimum S. Wats. Bot. King Expl. 315. 1871. 

 Polygonum Torreyi S. Wats. Amer. Nat. 7: 664. 1873. 



Annual, usually somewhat scurfy, the stems slender, simple or branched from the base, leafy 

 throughout, 5-15 cm. high. Leaves ovate to ovate-lanceolate, 5-15 mm. long, sessile or subsessile, 

 obtuse or acutish at apex, minutely scurfy-scabrous on the margins ; flowers mostly 2 or 3 in 

 the axils of most of the leaves ; pedicels 2 mm. long, equaling the stipule-sheaths ; calyx 2 mm. 



