88 American Midland Naturalist Monograph No. 7 



1. Chenopodium L. — Goosefoot. Pigweed 

 1. Plants more or less glandular and aromatic, not at all farinose. 

 2. Leaves sinuate-pinnatifid; pericarp not gland-dotted; fruit only 

 partly enclosed by the calyx; roadsides, waste ground, occa- 

 sional; nat. from Eur. July-Sept. Jerusalem Oak ...C. hotrys L. 



2. Leaves repand-dentate to subentire; pericarp gland-dotted; fruit 



completely enclosed by the calyx; waste ground, common; 



nat. from trop. Am. July-Oct. Mexican Tea 



- C. ambrosioides L. 



1. Plants not glandular or aromatic, but sometimes farinose. 



3. Flowers in globose clusters 1 cm or more in diameter, forming 



an interrupted spike, the calyx becoming red, succulent, and 

 strawberry-like at maturity; leaves triangular to lanceolate; 

 seeds horizontal, dull, 0.8 mm in diameter; sandy soil; Mc- 

 Henry and Peoria counties. May-Aug. Strawberry Pigweed 

 C. capitatum (L.) Aschers. 



3. Flowers in smaller glomerules; calyx not succulent. 

 4. Leaves sinuately dentate or entire. 



5. Sepals more or less prominently keeled in fruit. 



6. Pericarp loose, readily separating from the seed; leaves 

 thin; seeds horizontal. 

 7. Leaves green and glabrous or nearly so on both sur- 

 faces when mature, slender-petioled, lanceolate to 

 ovate, entire, or the lower ones sinuate-dentate; 

 woods, common. June-Oct. [C. sta?idleya?ium 

 Aellen] C. boscianurn Moq. 



7. Leaves densely farinose at least beneath, rather short- 



petioled, linear or lanceolate, often somewhat has- 

 tately toothed; sandy soil, occasional; native west of 

 the Mississippi R.; adv. in 111. July-Sept. Narrow- 

 leaved Goosefoot. [C. leptophylluin sensu auth., non 



Nutt.] -- ---C. pratcricola Rydb. 



6. Pericarp firmly adherent to the seed. 



8. Leaves more or less sinuately dentate. 



9. Leaves commonly densely farinose on the lower 

 surface; seeds 1-1.5 mm in diameter; cultivated 

 ground and waste places, common; nat. from 

 Eur. July-Sept. Lamb's Quarter. [C. viride L.; 

 C. missouricn.se Aellen; C. bushianum Aellen; 

 C. paganuyn Reichenb.] C. album L. 



9. Leaves green and glabrous on both surfaces, 

 triangular-ovate or somewhat deltoid-hastate, 

 often truncate at base; seeds 1 mm in diam- 

 eter; stem 30-90 cm tall; waste places, occasional; 



nat. from Eur. July-Sept. City Goosefoot 



C. urbicum L. 



