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This key has as its original framework the key and work of Donald Pinkava and Elinor Lehto of the Arizona State University. The goal is to make there work more useful and helpful to those attempting to identify plants in the Valley of the Sun. |
KEY OUTLINE
| Cacti Section 1 |
| Palms and Palm Like Plants Section 2 |
| Grasses (including Bamboos) and Grass-Like Plants Section 3 |
| Yuccas and Yucca-Like Plants Section 4 |
| Leaves Bladeless (Needles, Scales, Bristles) Section 5 |
| Leaves absent most of the year, drought conditions Section 6 |
| Vines Section 7 |
| Leaves Broad (Plants not of categories above) Section 8 |
| Leaves compound or appearing so Section 8A |
| Leaves simple Section 8AA |
| Leaves whorled or opposite Section 8B |
| Leaves alternate Section 8BB |
| Plants armed with thorns, spines or prickles Section 8C |
| Plants unarmed Section 8CC |
| Margins lobed, serrate, dentate, etc. Section 8D |
| Margins entire or undulate Section 8DD |
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2 1 Areoles bearing glochids; stems jointed, cylindric or flattened, not ribbed, not bearing prominent tubercles. 3 Areoles not bearing glochids; stems cylindric, sometimes bearing joints, ribs or prominent tubercles. 16 |
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3 2 Joints cylindric; spines sheathed when young: Chollas 4
Joints flattened (pads), spines not sheathed 9 |
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4
3 Lateral joints ¼” in diameter, 1-3” long; Plant bushy
Lateral joints ½” or more in diameter, over 3” long 5 |
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5 4 Branchlets ¾” or more in diameter, bearing elongate, low tubercles 6
Branchlets to ½” in diameter, smooth or bearing obscure
tubercles; plant
arborescent at maturity
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6
5 Branches in
whorls; plants
arborescent
Branches not in whorls; plants sometimes arborescent 7 |
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7 6 Plants arborescent, much branched; spines straw-colored 8
Plants sprawling shrubs, loosely branched; spines dark to light, but
not straw-colored
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8
7 Plants to 6’ tall; terminal joints short, very easily dislodged;
fruits not in chains
Plants to 12’ tall; terminal joints longer, not as easily dislodged;
fruits persisting in chains (variety with fewer and shorter spines on
more prominent tubercles is mammillata
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9
3 Joints broad, flattened, alternate or irregularly arranged;
Prickly Pears
10 |
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10
9
Joints 3-4 times longer than wide, tapering to a long slender tip
Joints not more than twice as long as wide, orbicular to obovate 11 |
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11
10 Central spines present, stout, whitish or yellowish
Central Spines, if present, not stout, yellowish to reddish 12 |
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12 11 Plants arborescent, with distinct trunks 13
Plants shrubs, not with distinct trunks 15 |
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13
12 Pads very thick; glochids few, scarcely visible; areoles widely
spaced
Pads less than ¾” thick; glochids numerous, obvious; areoles closely spaced 14 |
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14
13
Pads about ½” thick, green to blue-green
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15
12
Plants to 1 ½’ tall, mostly one joint high; joints obovate, gray,
wrinkled, with abundant red glochids
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16 2 Stems weak, arching or trailing, with long slender joints 17
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17
16
Stems gray, angled with 3-6 prominent longitudinal ribs bearing
blackish spines less than 1/8” long
Stems green (or purplish), ribbed but not angled; spines white or yellow to gray, more than ¼” long 1 ?? |
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18
17
Spines ½” (or less) long; ribs not prominent
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19
18 Older stems approximately 3” in diameter, turning red during cold or
dry periods, branching near the base
Older stems approximately 2” in diameter, green, branching above the
base
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20 16 Stems columnar, 6’ or more tall, ribbed; spines terete, straight (in one form absent) 21
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21 20
Plant
branching well above the constricted base
Plant branching near the unconstricted base, sometimes also above 22 |
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22
21
Ribs numerous,
12-17; spines uniform throughout plant
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23 20 Plants with prominent tubercles not arranged in longitudinal ribs 24
Plants with longitudinal ribs 25 |
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24
23 Tubercles
grooved above; central spine straight
Tubercles not grooved; central spine hooked
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25 23 Spines straight or slightly curved, but not hooked or distinctly twisted 26
At least some of the spines hooked or distinctly twisted 28 |
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26
25
Plants
cylindric, branching mostly at or below soil line
Plants globose, solitary or branched at base or above 27 |
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27
26 Spines terete,
dark-colored; plants often branched above base, apex not depressed,
not woolly
Spines flattened, golden yellow; plants solitary or branched at
base; apex depressed, woolly
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28
25
Plants nearly as wide as tall; central spines not twisted, sometimes
hooked
Plants much taller than wire; central spines twisted, often hooked
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| Palms and Palm Like Plants Section 2 |
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29 1 Plants palms or palm-like (some without trunks) 30
Plants not palm-like 53 |
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30 29 Leaves palmately veined; Fan Palms 31
Leaves pinnately veined; Feather Palms 43 |
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31 30 Trunks clustered, usually dward to 10’ tall, often hidden in foliage 32
Trunks solitary, of various heights 33 |
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32
31 Blades deeply divided into 5-10 segments, almost as leaflets
(appearing like dwarf bamboo); petioles not armed or irregularly so
Blades not deeply divided to appear as leaflets; petioles distinctly
armed with teeth
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33
31 Palms dwarf; trunk to 4’ tall; blades deeply divided into two equal
parts, each with minor divisions; petioles not armed
Palms not dwarf; trunks to 10’ or more tall; blades not deeply divided into two parts; petioles armed or not 34 |
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34 33 Midvein decidedly curled downward and backward; petiole not with marginal teeth 35
Midvein little or not at all curled downward and backward; petioles with or without marginal teeth 36 |
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35
34
Leaf blades to 6’ across; inflorexcence shorter than petiole; fruit
about ½” in diameter
Leaf blades to 4’ across; inflorescence longer than petiole; fruit
about 3/8” in diameter. |
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36
34
Very long,
stout spines terminating stiff network of old leaf sheaths.
No stout spines terminating old leaf sheaths 37 |
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37 36 Leaf blades with sharply drooping segments Fountain Palms 38
Leaf blades not with sharply drooping segments 39 |
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38
37 Trees to 60’
tall; leaves soft green; petioles armed.
Trees to 30’ tall; leaves bright shiny green; petioles sometimes
armed.
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39
37
Petiole smooth (or with
few small teeth at base) Petiole with marginal teeth 40 |
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40
39 Petiole with very fine
teeth; trunk with very many hair-like fibers.
Petiole with coarse teeth; trunk not with very many hair-like fibers (though some may be present) 4 ?? |
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41
40 Leaves blue-glaucous.
Leaves green or gray-green 42 |
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42
41
Trunks short to medium height, stout, about 2’ or more in diameter
at middle; blades very filiferous at maturity
Trunk tall, slender, about 1’ in diameter at middle; blades little
filiferous.
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43
30
Leaves coiled
upon unfolding from bud (circinnate venation); leaf segments (pinnae)
with revolute margins
43a
Leaves flat or folded lonitudinally in bud; pinnae not with revolute margins 44 |
| 43a 43 Leaflets with
prominent midveins Cycas revoluta Leaflets not with a prominent midvein Dioon edule |
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44
43
Lower pinnae represented by stiff, long, folded spines
45 Lower pinae not developed into spines 48 |
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45
44
Trunks clustered, usually dwarf
46 Trunks solitary, not dwarf 47 |
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46
45
Leaves white
floccose in interrupted lines on ribs beneath
Leaves not white floccose beneath |
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47
45 Trees slender to 100’
tall, with a rather dense crown of green to bluish green leaves,
often glaucous; fruit cylindric, 1-2” long, edible; seed more than 3
times longer than wide
Trees stout, to 60’ tall, with a dense crown of green to light green
leaves;, fruit about ¾” long, not considered edible; seed less than
3 times longer than wide
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48
44
Pinnae tips erose
(jagged); leaflets rigid, many-veined, broadened at apex.
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49
48
Leaves blue-glaucous,
arching, petiole spiny at base.
Leaves green; petiole not spiny 50 |
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50
49 Shrubby trees to 8’
tall; pinnae to
20 pairs in number
Trees 20-50 feet or more tall; pinae many, 40 pairs or more 51 |
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51
50 Petiole
fibrous shaggy
Petiole not fibrous shaggy 52 |
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52
51
Pinnae with lateral veins prominent above, chaffy on midvein and
margins beneath, at least when young; stems branching at maturity;
leaf rachis yellow to red beneath.
Pinnae with lateral vines prominent beneath, coarsely chaffy on only
midvein beneath; leaf rachis slightly grayish beneath; stems not
branching.
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| Grasses (including Bamboos) and Grass-Like Plants Section 3 |
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53 29 Plants grasses (including bamboos) or grass-like; leaves parallel veined, ensheathing stems 54
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54 53
Plants aquatic or
semiaquatic; leaves strongly ascending; Cattails
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55 54 Culms(stems) terete, jointed, or various heights; all leaf sheaths with blades, these sometimes deciduous 56
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56 55 Blades much broader than the sheath, stalked, deciduous from the joint at sheath; sheaths sometimes persistent Bamboos 57
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57 56 Culms flattened on one side above the node 58
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58 57 Culms becoming black
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59 58
Culms flattened on
one side above node
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60 57 Culms to about 3' tall, from running rhizomes, not clumping 61
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61 60
Internodes solid,
short; culms to 1 foot tall, purplish
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62 60 Rhizome internodes with many scattered roots developing; culms with several branches at a node; sheath bristles stiff, scabrous 63
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63 62 At least some
internodes swollen in the middle (intensifies if pot-bound)
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64 63
Stems to 60' or
more tall, 2-4" in diameter at maturity, deep green
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65 56 Leaf margins finely serrate (serrulate) 66
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66 65
Culms 18-36" tall,
less than 1/8" in diameter, scabrous below the inflorescence;
inflorescence narrow, to 12" long
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| Yuccas and Yucca-Like Plants Section 4 |
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67 53 Plants yuccas or yucca-like, often scapose; leaves in a rosette, basal or atop a trunk (occasionally well distributed along trunk in young plants), often linear, sometimes succulent 68
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68 67 Leaves with marginal prickles 69
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69 68 Leaves very succulent, usually spotted with a lighter color; no fibers in center of leaf; basal rosette to 2' in diameter Aloe spp.
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70 69
Blades thin, to 1"
wide, about 3' long, tapering to long foliaceous tips; margins
bearing numerous tiny recurved prickles
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71 68 Leaf margins serrulate to entire 72
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72 71 Leaves rigid, dagger-like 73
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73 72 Leaves to about 8" long, about 1/2" wide; arborescent, much branched Yucca brevifolia
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74 72 Arborescent, stems often with swollen bases; leaf margins sharply serrate Yucca elephantipes
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75 71 Plants at maturity with trunks; leaf blades flat, narrow, with many fine fibers Yucca elata
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76 75 |