Technical Dichotomous Key: A Scientific Guide for Pollen Identification

1. Apertures present

2. Colporate

3. Sculpting on exine reticulate

4. Onci present

5. Exine less than 1 μm thick

Basswood

5. Exine more than 1 μm thick

Dock

4. Onci absent

Willow

3. Sculpting on exine not reticulate

6. Onci present

Sage

6. Onci absent

Ragweed

2. Porate or colpate

7. Colpate

8. Onci present

9. Sculpting on exine reticulate

Ash

9. Sculpting on exine scabrate

Oak

8. Onci absent

10. Shape oblate

Sycamore

10. Shape sphere

Maple

7. Porate

11. Shape triangular

12. Aspis present

Hickory

12. Aspis absent

Sedge

11. Shape not triangular

13. Polyporate

14. Onci present

15. Aspis present

Walnut

15. Aspis absent

Hackberry

14. Onci absent

16. Number of pores greater than 10

Goosefoot

16.  Number of pores less than 10

Plantain

13. Stephanoporate

17.  Monoporate

18.  Aspis present

Grass

18. Aspis absent

Cattail

17.  Multiple pores

19.  Diporate and Triporate

20. Diporate

Mulberry

20. Triporate

21. Aspis present

22. Sculpting on exine scabrate

Ironwood

22. Sculpting on exine rugulate

Birch

21. Aspis absent

Hemp

19. Tetraporate and greater

23. Size below 19 mm

Nettle

23. Size above 19 mm

24. Aspis present

Alder

24. Aspis absent

Elm

1. Apertures absent

25. Bladders present

26.  Sharp bladder sculpting change

Spruce

26.  Gradual bladder sculpting change

27. Dorsal cap thick

Pine

27. Dorsal cap of variable thickness

Fir

25.  Bladders absent

28.  Protoplast star-shaped

Juniper

28.  Protoplast circular

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