874 AMMIACEAE 



36. PHELLOPTERUS Nutt. 



Perennial acaulescent or nearly acaulescent herbs, with thick roots. Leaves basal : 



blades bipinnate. Flowers inconspicuous. Involucres rarely present. Involucels of hyaline 



bractlets. Sepals manifest. Petals pink, purple or rarely white, inflexed at the apex. Disk 



flat, stylopodium wanting. Fruit oblong to orbicular, slightly dorsally flattened : carpels 



with 3-5 wings of about equal breadth : oil-tubes usually 3 in the intervals. Seeds flattened. 



Corolla white: bractlets of the invnlucel entire : fruit 8-12 mm. long. 1. P. montanus. 



Corolla pinlc : bractlets of the involucel fringed : fruit 4 mm. long. 2. P. macrorhizus. 



1. Phellopterus montanus Nutt. Roots elongated, sometimes fusiform. Foliage 

 often pubescent when young. Leaves clustei-ed ; blades glaucous, bipinnately parted or 

 bipinnate, 4-10 cm. long, the segments pinnatifid, suggesting pinnae of many common 

 species of ferns : peduncles very short, solitary or clustered, the umbels during anthesis 

 appearing sessile in the cluster of leaves : rays 6-12, unequal, 6-18 mm. long : bracts of 

 the involucre and involucels conspicuous, membranous, entire : fruit oblong in outline, 

 8-12 mm. long: wings of the carpels 3-5, very thin, from a thicker ;base ; oil-tubes 1-3 in 

 the intervals, and 4-8 on the commissural side. 



On dry slopes or hillsides, Wyoming to Nebraska and Texas. Spring. 



2. Phellopterus macrorhizus (Buckl. ) Coult. & Rose. Similar to P. montanus in 

 habit, but with peduncles becoming twice as long as the leaves : umbels with longer rays 

 and pedicels : bractlets of the involucels lacerate at the apex : corolla pink : fruit 4 mm. long. 



On prairies, eastern Texas. Spring and summer. 



37. CYMOPTERUS Raf. 



Perennial dwarf acaulescent herbs. Leaves alternate, basal : blades pinnate or bipin- 

 nate. Involucre generally wanting. Involucel of foliaceous bractlets. Umbels dense. 

 Hypanthium truncate or supporting small sepals. Corolla white or yellow. Stylopodium 

 wanting. Fruit dorsally flattened, broad, normally glabrous : carpels with the dorsal and 

 intermediate ribs filiform or winged, the lateral wings broad, corky, those of each carpel 

 coherent until maturity : oil-tubes small, 4-8 in each interval, and 8-14 on the commissural 

 side. Seeds flat. 



1. Cymopteris acaulis (Pursh) Rydb. Plant glabrous, 7-20 cm. tall. Peduncles 

 clustered, mostly surpassed by the leaves: umbels congested: bractlets linear, entire: 

 corolla white : fruit oval, 6-8 mm. long, each carpel with 3-5 broad wings. 



On dry plains, Assiniboia to Arkansas and Colorado. Spring. 



38. POLYTAENIA DC. 



Perennial caulescent herbs, with thick roots. Leaves alternate : blades pinnately 

 decompound. Flowers in compound umbels. Involucres and involucels of few narrow 

 bracts or the former wanting. Sepals triangular. Petals broadest above the middle, in- 

 flexed at the apex. Disk without a stylopodium. Fruit strongly flattened dorsally : car- 

 pels with the dorsal and contiguous ribs corky but obscure and thick broadly winged lateral 

 ribs with a nerve near the margin : oil-tubes numerous, 12-18 accompanied by smaller ones 

 irregularly disposed. 



1. Polytaenia Nuttdllii DC. Root fusiform. Foliage nearly glabrous : stems 2-9 

 dm. tall, often branching above, slightly scabrous : leaf-blades twice pinnately divided or 

 parted, 5-20 cm. long, tlie lower ones long-petioled, the upper nearly sessile ; segments nar- 

 rowly cuneate, toothed or lobed : umbels peduncled, 2-7 cm. broad : bracts of the in- 

 volucres wanting : rays 6-12, 2-3 cm. long, a few conspicuously short : pedicels 2-4 mm. 

 long : corolla 2.5-3 mm. broad : fruit broadly oblong, 6-10 mm. long, the edges thickened, 

 the faces often depressed. 



In dry soil, Michigan to Wisconsin, Tennessee and Texas. Spring.— P. Kuttallii Texdna Coult. & 

 Rose, has obovate fruit with thinner wings, filiform dorsal and intermediate ribs and broader more dis- 

 tinct oil-tubes ; it occurs in southern Texas. 



39. OXYPOLIS Raf. 

 Perennial caulescent herbs of marshy localities, with glabrous foliage. Leaves alter- 

 nate : blades pinnate or ternate, or rarely reduced to hollow septate phyllodes : leaflets 

 toothed. Flowers perfect, in compound umbels. Sepals acute. Petals white. Disk with 



