BUCKWHEAT FAMILY. 555 
Plants erect or ascending, rather stout. 
Achene invested by the calyx. 
Leaves oval, oblong or obovate, persistent. 25. P. ereclum. 
Leaves narrowly lanceolate or linear-oblong, persistent. 27. P. ramosissimum. 
Leaves oblong-lanceolate or narrowly oblong, fugacious. 28. P. camporum. 
Achene much exserted beyond the calyx. 26. P. exsertum., 
Plants strictly erect and very slender. s Lp. ot ; 
Leaves with a lateral impression on either side of the midvein; fruiting pedicels stout, erect. 
29. P. tenue. 
Leaves without lateral impressions; fruiting pedicels slender, deflexed. 30. P. Douglasii. 
4, Flowers in axillary and terminal clusters, racemes or panicled racemes; stems mostly twining. 
Stems twining; herbaceous vines. 
Outer segments of the calyx unchanged, or keeled in fruit. 
Achene granular and dull; ocreae not bristly. gu. P. Convolvulus. 
Achene smooth and shining; ocreae bristly. 32. P. cilinode. 
Outer segments of the calyx conspicuously winged in fruit. 
Calyx-wings not incised. 
Fruiting calyx 5'’-6’’ long, the wings crisped. 33. P. scandens. 
Fruiting calyx 3''-4'' long, the wings rather flat. 34. P. dumetorum. 
Calyx-wings incised. / 4 F 35. P. cristatum. 
Stems stout, erect, tall; outer calyx-segments winged in fruit. 36. P. Zuccarinii. 
5. Flowers in capitate clusters or racemes; stem climbing by recurved prickles. 
Leaves sagittate; achene 3-angled. 37. P. sagittatum. 
Leaves halberd-shaped; achene lenticular. 38. P. arifolium. 
1. Polygonum viviparum LL. Alpine 
Bistort. (Fig. 1318.) 
Polygonum viviparum I,. Sp. Pl. 360. 1753. 
Perennial by a corm-like rootstock, mostly gla- 
brous and somewhat glaucous; stems solitary or 
clustered, erect, simple, slender, 2’-10/ tall. Basal 
leaves oblong or lanceolate, 1/-8’ long, rather acute 
at the apex, cordate or subcordate at the base, long- 
petioled; stem leaves narrowly lanceolate or linear, 
1/-3/ long, the lower petioled, the upper sessile, 
their margins often revolute; ocreae long, clasping 
below, open above; raceme solitary, terminal, nar- 
row, rather dense, bearing a number of dark colored 
bulblets about its base; calyx 5-parted, pale rose- 
color or white; stamens 8, exserted; style 3-parted, 
its branches exserted; achene oblong, 3-angled. 
Greenland and Labrador to Alaska, south to the high 
sumunits of the mountains of New England, and in the 
Rocky Mountains to Colorado. Also in arctic and 
alpine Europe and Asia. June-Aug. 
/ 
2. Polygonum amphibium J,. Water Persicaria. (Fig. 1319.) 
Polygonum amphibium 1, Sp. Pl. 361. 1753. > 
Aquatic, perennial, glabrous when mature; : 
stem floating or submersed, simple or spar- : 
ingly branched, 4°-20° long. Leaves oblong, 
elliptic or elliptic-lanccolate, 14/—4/ long, peti- 
oled, obtuse or subacute at the apex, slightly 
inequilateral, rounded or narrowed at the 
base, sometimes ciliate; ocreae cylindric, those 
of the branches often longer than the inter- 
nodes, their limbs sometimes spreading, usu- 
ally glabrous; raceme terminal, usually soli- 
tary, 4’-1’ long, dense, erect, oblong or ovoid; 
calyx rose-color, 5-parted; stamens 5, exserted; 
style 2-cleft, exserted; achene orbicular ob- 
long, lenticular, 11%4’’ long, biconvex, black, 
smooth and shining, or granular. 
In ponds and lakes, Quebec to Alaska, south to 
northern New Jersey, Kentucky, Colorado and 
California. Ascends to 2000 ft. in the Adiron- 
dacks.}, Also in Europe. July—Aug. 
