Genus 6. 



BUCKWHEAT FAMILY. 



665 



Calyx more or less colored, somewhat curved. Sepals 4, the 2 lateral ones overlapping the 

 others. Stamens 4, and alternating with the sepals, or 5, the fifth one opposite the lower 

 sepal ; filaments barely flattened, erect or slightly spreading. Styles 2, conspicuously 

 exserted, recurved or curled. Achenes lenticular, strongly biconvex, brown or cream- 

 colored, smooth and shining. Endosperm horny. Cotyledons accumbent. [Derivation 

 uncertain.] 



Two known species, the following typical, the other Japane 



i. Tovara virginiana (L.) Raf. Virginia 

 Knotweed. Fig. 1629. 



Polygonum virginianum L. Sp. PI. 360. 1753. 

 Tovara virginiana Raf. Fl. Tell. 3 : 12. 1836. 



Plants nearly glabrous or strigose-pubescent, stem 

 erect or arching, simple or branched above, i°-4° tall. 

 Leaves ovate or elliptic-ovate or ovate-lanceolate, short- 

 petioled, acuminate at the apex, 2'-6' long, sparingly 

 ciliate; ocreae cylindric, strigose, fringed with short 

 bristles; racemes spicate, erect, terminal and axillary, 

 naked, greatly elongated and interrupted, sometimes 12' 

 long; calyx curved, greenish or rose-color, 4-cleft; 

 stamens 5 ; style long, exserted, 2-parted to the base, 

 its branches^ at length curled ; achene 2" long, ovate- 

 oblong, lenticular, strongly biconvex, dark brown or 

 cream-colored, smooth, shining. 



In woods, Nova Scotia to Minnesota, south to Florida and 

 Texas. Ascends to 4000 ft. in North Carolina. July-Nov. 



7. PERSIC ARIA (Tourn.) Mill. Gard. Diet. Abr. Ed. 4. 1754. 



Annual or perennial, often pubescent or glandular caulescent herbs, various in habit, 

 never twining nor climbing. Leaves alternate, entire, continuous with the ocreae, often 

 glandular-punctate. Ocreae cylindric, mostly membranous, truncate, naked, ciliate or fringed 

 with bristles. Racemes spike-like, varying from linear to ovoid, dense and erect, or few- 

 flowered, lax and drooping. Ocreolae funnelform, naked, ciliate or fringed. Pedicels rather 

 stout, articulated at the base of the calyx. Calyx more or less colored, varying from white 

 and green to red, often glandular-punctate, investing the achene. Sepals mostly 5, 2 wholly 

 exterior, 2 wholly interior and 1 with one margin interior and the other exterior, none of 

 them winged or keeled. Stamens varying from 4 to 8, included or exserted; filaments not 

 dilated, erect or nearly so. Styles mostly 2, sometimes 3, usually partially united, included 

 or exserted; stigmas capitate. Achene mostly lenticular, sometimes 3-angled and lenticular 

 on the same plant, usually black, smooth or granular. Endosperm horny. Cotyledons 

 accumbent. [From Persica, from the resemblance of the leaves to those of the peach.] 



About 125 species, widely distributed. Type species : Polygonum Persicaria L. 



Racemes solitary or paired. 



Raceme short and stout ; leaves obtuse or merely acute. 1. P. amphibia. 



Raceme long and slender ; leaves acuminate. 2. P. Muhlenbergii. 



Racemes several or numerous. 



Ocreae not fringed with bristles. 



Racemes drooping. 3. P. lapathifolia. 



Racemes erect. 



Style and stamens included or slightly exserted ; achene-faces concave. 



Achene biconvex, broadly oblong ; plants perennial. 4. P. portoricensis. 



Achene concave, orbicular ; plants annual. 5. P . pennsylvanica. 



Style or stamens conspicuously exserted ; achene-faces swollen. 6. P. longistyla. 



Ocreae bristle-fringed. 



Ocreae without spreading borders ; leaves relatively narrow, short-petioled or sessile ; stigmas 

 minute. 

 Stem, branches and peduncles rough-glandular. 7. P. Careyi. 



Stem, branches and peduncles not rough-glandular. 

 Sepals not glandular-punctate. 



Racemes short, stout and compact. 



Ocreae inconspicuously fringed ; achene narrowly ovoid. ■ 8. P. Persicaria. 

 Ocreae conspicuously fringed ; achene broadly ovoid. 9. P. persicarioides. 



Racemes slender, elongated and lax or interrupted. 



Ocreae strigose, fine-bristly ; leaves glabrous or somewhat strigose. 



Calyx greenish-white; ocreolae copiously long-bristly.io. P. opelousana. 

 Calyx white, pink or purplish-pink; ocreolae sparingly fine-bristly. 



P. hydropiperoid.es. 

 leaves conspicuously ap- 

 12. P.setacea. 



Ocreae hirsute or appressed-hirsute, coarse-bristly 

 pressed-hirsute. 

 Sepals glandular-punctate. . 



Achene granular and dull; racemes drooping. 13. P. Hydropiper, 



Achene smooth and shining; racemes erect. 14. P. punctata. 



Ocreae with spreading border ; leaves broad, long-petioled ; stigmas large. 



15. P. orientalis. 



