1.  Leaves pinnate.....2.
1.  Leaves palmate.....3.

2.  Leaves induplicate in vernation.....4.
2.  Leaves reduplicate in vernation.....5.

4.  Multistemmed habit, descending curved leaves, slender trunk.....Phoenix reclinata
4.  Solitary habit, if multistemmed, central leaves ascending and robust trunk.....6.

6.  Leaves about six meters in length.....7.
6.  Leaves one to three meters in length, leaves descending.....8.

7.  Dark/dull green leaf color, dark brown crumbly area along trunk.....Phoenix canariensis (more pictures: 1, 2)
7.  Gray-green leaf color, no dark brown crumbly area along trunk.....Phoenix dactylifera (more pictures: 1, 2)

8.  Leaflets many-ranked, pale green color.....Phoenix zeylanica (another picture)
8.  Leaflets few-ranked, bluish-green color.....Phoenix sylvestris (another picture)

5.  Leaves strongly recurved towards trunk.....Butia capitata (another picture)
5.  Leaves not recurved towards trunk.....9.

9.  Leaflets short and stiff, acute.....Jubea chiliensis
9.  Leaflets long virith pendulous tips.....Syagrus romanzoffiana (another picture)

3.  Leaf with pronounced costa (costapalmate).....10.
3.  Leaf with no costa (palmate.....11.

10.  Costa strongly arched, no petiolar spines.....12.
10.  Costa not strongly arched, petiolar spines (although some without.....13.

12. Leaves bluish-green, sparse crown.....Sabal uresana
12. Leaves dull green, dense crown.....Sabal palmetto (more pictures: 1, 2)
 
13. Leaves bluish-gray green.....Brahea armata (more pictures: 1, 2, 3, 4, 5, 6)
13. Leaves bright or dull green.....14.

14.  Petiolar spines white, palms no taller than ten meters.....Brahea edulis
14.  Petiolar spines orange when present, palms attain 15-25 meters in height.....15.

15.  Trunk slender, to 25 meters tall, white patch on abaxial surface of leaf where the petiole joins the blade.....
        Washingtonia robusta (more pictures: 1, 2, 3, 4)
15.  Trunk robust, to 15 meters tall, no white patch on abaxial surface of leaf (or not as prominent.....Washingtonia filifera

11.  Solitary habit, trunk covered with dense fibers, monoecious.....Trachycarpus fortunei (more pictures: 1, 2)
11.  Multistemmed habit, trunk slightly covered with fibers, dioecious.....Chamaerops humilis (more pictures: 1, 2, 3)

Director - Elizabeth Davison
UA Campus Arboretum - University of Arizona
PO Box 210036 - Tucson AZ, 85721
Telephone: 520-621-7074