sometimes highly colored; ovary superior; style 2- or 3-cleft or -parted; stigmas 

 capitate; achene trigonous or lenticular, 1 -celled, sometimes both kinds on the 

 same plant, light-tan through reddish-brown to black. 



A cosmopolitan genus of about 320 species. Persicaria Mill. 



The seeds of these species are eaten by many kinds of songbirds, upland game 

 birds, waterfowl, marsh birds, shorebirds and small mammals. The plants are 

 often eaten by browsers. It has been noted that where these plants are in abun- 

 dance about the borders of an aquatic area the region is apt to be popular with 

 waterfowl. 



1. Flowers in terminal spikelike or narrowly racemelike inflorescences; blades 

 never jointed to petioles; styles never indurate and persistent or if 

 so less than 0.5 mm long; plants often aquatic or semiaquatic, never 

 vinelike (12) 



1. Flowers not in terminal spikelike or racemelike inflorescences, or if so then 



a joint (zone of abscission) present between blade and petiole or 

 else the plants vinelike (2) 



2(1). Leaf blade jointed or articulated to petiole (6) 



2. Leaf blade not jointed to petiole (3) 



3(2). Plants with erect or ascending stems, not at all vinelike; styles persistent, 



deflexed, hook- or hornlike, rigid, about 3 mm. long 



1. P. virginianum. 



3. Plants vinelike or with long weak reclining stems; styles not rigid, persistent 



and elongate (4) 



4(3). Stems 4-angled, weak and reclining, not twining 2. P. sagittatum. 



4. Stems twining (5) 



5(4). Perianth after anthesis becoming about 3.5 mm. long, closely investing the 



achene, the 3 outer sepals minutely keeled but never winged 



3. P. Convolvulus. 



5. Perianth after anthesis eventually about 6 mm. long, the outer 3 sepals with 



dorsomedial wings 0.25-1 mm. broad 4. P. cristatum. 



6(2). Flowers crowded toward the ends of the branches (appearing to be ter- 

 minal spikes) or else solitary or in 2's or 3's in the upper nodes (7) 



6. Flowers in axillary clusters along the stem (10) 



7(6). Strong perennial, often rhizomatous; flowers solitary or in 2's or 3's at 

 the upper nodes 5. P. texense. 



7. Taprooted annual with the ends of the branches appearing to be terminal 



spikes (8) 



8(7). Stems slender usually less than 1.5 dm. tall; flowers in leafy-bracted spike; 

 anther-bearing stamens 3(9) 



8. Stems stout, with ascending branches, striate; upper leaves reduced to incon- 



spicuous bracts; perianth lobes usually 6; stamens 6 to 8 



6. P. argyrocoleon. 



9(8). Floral bracts mostly plainly white-margined, the upper ones often no 

 longer than the flowers 7. P. confertiflorum. 



9. Floral bracts only slightly or not white-margined, the upper ones usually 



exceeding the flowers 8. P. Kelloggii. 



10(6). Stems usually decumbent or prostrate, upper leaves not greatly reduced; 



achenes usually brown, dull and striated or roughened 



9. P. aviculare. 



10. Stems usually erect or ascending; achenes dark-brown or black (11) 



808 



