Jones: Flora of Illinois 27 



16. Leaves with sheathing stipules; corolla none; calyx 5-lobed; 

 flowers perfect; fruit an achene 32. Polygonaceae 



16. Leaves without sheathing stipules. 



17. Plants dioecious; perianth 6-parted ; stamens 6. 



18. Flowers in drooping racemes or panicles; styles 3, dis- 

 tinct; fruit a 3-angled or -winged capsule 



137. DiOSCOREACEAE 



18. Flowers in umbels: stigmas thick, almost sessile; fruit a 



small bluish black berry SmiUix in 130. Liliaceae 



17. Flowers perfect; corolla sympetalous; stamens 5. 



19. Corolla funnelform; fruit a capsule; plants often with 



milky juice 105. Convolvulaceae 



19. Corolla rotate, purple or blue (or white) ; anthers 

 yellow, connivent around the style, opening by api- 

 cal pores; berries red; juice watery 



Solanum dulcamara in 107. Solanaceae 



15. Plants bright yellow or orange, parasitic on other plants and 

 lacking chlorophyll; leaves reduced to scales; fruit a capsule 

 Cuscuta in 105. Convolvulaceae 



Section II. Aquatic Plants, Floating on or Submerged in Water 



1. Plants very small, free-floating, thalloid, without stems and leaves 



142. Lemnaceae 



1. Plants larger, normally with leaves and usually with stems. 

 2. Leaves entire or finely toothed. 



3. Blades roundish, cordate at base, or peltate; flowers large, solitary. 



4. Leaves peltate; carpels immersed in a fleshy turbinate receptacle 



6. Nelumbonaceae 



4. Leaves and carpels otherwise 5. Nymphaeaceae 



3. Blades neither cordate nor peltate. 



5. Floating leaves spatulate; leaves opposite, small; flowers minute, 



unisexual, sessile, 1-3 in the axils; stamen I; styles 2, filiform; 



fruit 4-lobed, notched at the apex 85. Callitrichaceae 



5. Leaves never spatulate. 



6. Plants acaulescent; leaves long, linear; fertile flowers on long 



slender scapes; fruit many-seeded 



Vallisneria in 138. Hydrocharitaceae 



6. Plants with stems. 



7. Leaves alternate, or all basal, or imperfectly opposite. 



8. Flowers green, in spikes; sepals 4; stamens 4; carpels usually 



4; stipules present, membranous; fruit 1-seeded 



129. Potamogetonaceae 



8. Flowers not green. 



9. Leaves mostly parallel-veined. 

 10. Ovary or ovaries superior. 



11. Ovaries several or many, simple, 1-ovuled, forming 



achenes 126. Alismaceae 



11. Ovary one, compound; fruit several-seeded 



134. Pontederiaceae 



10. Ovary inferior 138. Hydrocharitaceae 



9. Leaves net-veined. 



