308 IOWA ACADEMY OF SCIENCE 
KEY TO DICOTYEEDONE^ 
1. FIs. crowded in dense heads surrounded by an 
involucre, the 5 stam. united by their anthers 
into a tube 
1. FIs. not crowded, or if so not involucrate, or 
the stam. not united 
2. FIs. with no perianth, or with only one circle, 
in this case arbitrarily called a calyx 
2. FIs. with both calyx and corolla 
3. Petals separate from one another 
3. Petals united at least at base into a tube 
4. Stam. and pist. in different fls. on different 
plants (dioecious) 
4. Stam. and pist. in different fls.' on the same 
plant (monoecious) 
4. Stam. and pist. in the same fl. (perfect) 
5. Vines with opposite compound Ivs. 
5. Vines with alternate Ivs. 
5. Trees or Shrubs 
■ 5. Herbs 
6. Evs. opposite 
6. Evs. alternate 
7. Shrub with 2 short spines at each node 
7. Spineless 
8. Twigs scaly- roughened ; sep. 4; shrub 
8. Twigs smooth and shiny; sep. 4-12 or none; 
tree 
8. Twigs not shiny; bud scales downy; tree 
9. Fls. in catkins with no perianth, each in the axil 
of a scale 
9. FIs. with well defined perianth 
10. Bark aromatic to smell and taste; sep. 6 
10. Not aromatic; sep. 4 
11. Evs. deeply palmately lobed or divided 
11. Evs. 2-3 times divided into small Iflts. 
11. Evs. simple 
12. Evs. entire, with 2 narrow lobes at base 
12. Evs. toothed, oval, pointed 
13. Trees or shrubs 
13. Woody vines 
’13. Herbs 
14. Evs. opposite 
14. Evs. alternate 
15. Both stam. and pist. fls. in catkins or dense heads 
15. Only the stam. fls. in catkins or dense heads 
16. Heads of fls. globular; cal. absent 
16. Fls. in cylindric catkins 
17. Stipules early falling off 
17. Stipules forming a sheath around the twig 
Voi.. XXVIII, 1921 
134 
2 
4 
3 
38 
99 
5 
13 
22 
Ranunculaceae 
Vitaceae 
6 
11 
8 
7 
Rutaceae 
9 
Eleagnaceae 
Aceraceae 
Oleaceae 
Salicaceae 
10 
Eauraceae 
Urticaceae 
Urticaceae 
Ranunculaceae 
12 
Polygonaceae 
Urticaceae 
14 
Vitaceae 
21 
Aceraceae 
15 
16 
19 
17 
18 
Hamamelidaceae 
Platanaceae 
