14 American Midland Naturalist Monograph No. 2 



2. Stem not prickly; chaff of the receptacle not as above, sometimes absent; stamens 



5, united by their anthers (syngenesious) 152. CoMPOSITAE 



1 . Flowers not sessile in dense heads on a common receptacle surrounded or subtended 

 by an involucre of bracts. 



3. Corolla of separate petals (or apparently so), or corolla absent (the calyx sometimes 



petal-like). 

 4. Leaves with black or pellucid dots, opposite, entire; flowers yellow or pink. 

 5. Styles 2-6 106. Hypericaceae 



5. Style 1 121. Primulaceae 



4. Leaves not punctate. 



6. Leaves with stipules; petals minute or absent; stigmas 2-4. 



7. Petals 2 or 3 ; capsule several-seeded, the seeds reticulated; leaves oblanceo- 

 late or obovate ; small plants of wet ground 59. Elatinaceae 



7. Petals none; fruit a 1 -seeded utricle 55. Illecebraceae 



6. Leaves without stipules. 



8. Plants with milky juice; capsule deeply 3-lobed; upper leaves usually 



whorled; flowers small, white or greenish 94. EuPHORBIACEAE 



8. Plants with colorless juice. 



9. Flowers solitary; stamens 6; ovary superior, 3-loculed 



genera in 31. LiLlACEAE 



9. Flowers not as above. 



10. Flowers irregular, in spikes or racemes; sepals 5, three of them small, 



and two larger and colored like the 3 petals; fruit flattened 



93. POLYGALACEAE 



10. Flowers regular, not in spikes or racemes. 

 I I . Leaves in whorls. 



12. Flowers axillary; leaves in fives or sixes; petals none; sepals 

 5; fruit a small 3-valved capsule; plants annual, prostrate 

 56. AlZOACE.AE 



12. Flowers in cymes or panicles; petals 5; plants perennial. 



13. Leaves (at least the lower) in threes; flowers in cymes; 



petals entire; fruit a follicle 



Sedum in 75. Crassulaceae 



13. Leaves mostly in fours, acuminate; inflorescence paniculate; 



petals laciniate; fruit a capsule 



5i7e/ie in 58. Caryophyllaceae 



I 1 . Leaves not whorled (or if so, not thick and succulent). 



14. Calyx and corolla absent; flowers small, green, solitary, axil- 

 lary; leaves spalulate or linear; styles 2, filiform; fruit 



notched; small plants of wet soil 95. Callitrichaceae 



14. Calyx present; corolla present or absent. 

 15. Sepals separate. 



16. Petals none; flowers crowded into an interrupted spike; 

 calyx woolly; bracts scarious; leaves lanceolate, sessile 



52. Amaranthaceae 



16. Petals usually present; inflorescence not as above. 



1 7. Sepals 2; stem-leaves a single pair; petals pink or 



while; stamens 5; style 3-cleft 



Claptoitia in 57. PoRTULACACEAE 



17. Sepals 5; leaves more than I pair. 

 18. Sepals equal or nearly so. 



19. Petals white (sometimes absent) ; leaves with 

 ordinary flat blades; stems usually soft.... 



58. Caryopi iyi.i.aceae 



19. Petals yellow; leaves small, scale-like or sub- 

 ulate, appressed or nearly erect 



Sarothra in 106. Hypericaceae 



18. Sepals unequal, the 2 outer much narrower than 

 the 3 inner ones; [letals yellow, greenish, or 



