# Dichotomous Key/Cycas

Key to the species of Cycas:

## Cycas

* CYC1: Ovules coated with hair.
* CYC2: Ovules lacking hair.

## CYC1

* Cycas taitungensis: Pinnae flat
* Cycas revoluta: Pinnae rolled near the tip

## CYC2

* CYC3: Expanded portion of Megasporophyll leaf with closely parallel toothlike projections.
* CYC4: Expanded portion of megasporophyll leaf without closely parallel toothlike projections.

## CYC3

* CYC5: Male cones are stiff and rigid
* CYC6: Male cones are soft

## CYC4

* CYC10: Spongy tissue present in seeds.
* CYC11: Spongy tissue not present in seeds.

## CYC5

* CYC7: Hard seed coat is ribbed.
* Cycas panzhihuaensis: Hard seed coat is not ribbed.

## CYC6

* CYC8: Soft seed coat is not fibrous; hard seed coat is studded with wart-like projections
* CYC9: Soft seed coat is fibrous; hard seed coat is smooth.

## CYC7

* Cycas curranii: Pinnae over 6 millimeters wide; seeds over 40 millimeters long.
* Cycas wadei: Pinnae less than 6 millimeters wide; seeds less than 40 millimeters long.

## CYC8

* CYC14: Top of megasporophyll spine much longer and wider than lateral spines
* CYC15: Top of megasporophyll spine similar to lateral spines

## CYC9

* Cycas lindstromii: Male cones less than 5 centimeters in diameter; Stems underground
* CYC17: Male cones over 5 centimeters in diameter; stem rises at least partially above ground.

## CYC10

* CYC20: Seeds have a wing on the tip
* CYC21: Seeds do not have an obvious wing on the tip

## CYC11

* CYC12: Hard seed coat has a fibrous layer
* CYC13: Hard seed coat does not have a fibrous layer.

## CYC12

* Cycas beddomei: Pinnae less than 5 millimeters wide
* CYC27: Pinnae over 5 millimeters wide.

## CYC13

* CYC37: Basal pinnae gradually reducing in size
* CYC38: Basal pinnae not gradually reducing in size

## CYC14

* CYC49: Pinnae less than 11 millimeters wide.
* CYC50: Pinnae over 11 millimeters wide

## CYC15

* CYC54: Pinnae simple
* CYC55: Pinnae dichotomously divided

## CYC16

* Cycas chamaoensis: Male cones rounded and tapering from the middle toward each end; Spindle-shaped
* CYC63: Male cones elliptical or oval-shaped

## CYC17

* Cycas hongheensis: Leaves have a distinct longitudinal ridge and covered with hair.
* CYC19: Leaves mostly flat and at least the top is without hair.

## CYC18

* Cycas siamensis: Basal pinnae reducing to spines
* CYC64: Basal pinnae not reducing to spines.

## CYC19

* CYC16: Phelloderm smooth
* CYC18: Phelloderm corky

## CYC20

* Cycas rumphii: Megasporophyll lateral spines are small bumps
* CYC22: Megasporophyll lateral spines distinct

## CYC21

* CYC23: Pinnae are broad, very glossy, and bright green
* CYC24: Pinnae are slightly glossy; Pinnae are bluish when new

## CYC22

* Cycas micronesica: Apical spine is less than 15 millimeters long
* CYC25: Apical spine is over 15 millimeters long

## CYC23

* Cycas edentata: Plants found in the Philippines.
* Cycas litoralis: Plants found in Thailand

## CYC24

* Cycas thouarsii: Fewer broad, short cataphylls present. Plants of Madagascar
* Cycas zeylanica: Numerous thin, long cataphylls present. Plants of Sri Lanka.

## CYC25

* Cycas boubainvilleana: Pinnae over 12 millimeters wide
* CYC26: Pinnae less than 12 millimeters wide.

## CYC26

* Cycas falcata: Petioles usually spiny.
* Cycas seemannii: Petioles without spines, or with few spines.

## CYC27

* CYC28: Pinnae less than ten millimeters wide
* CYC29: Pinnae over ten millimeters wide.

## CYC28

* CYC30: Lateral megasporophyll teeth less than four millimeters long.
* CYC31: Lateral megasporophyll teeth over four millimeters long.

## CYC29

* Cycas pranburiensis: Petioles lacking spikes or bristles
* CYC32: Petioles have spines or bristles

## CYC30

* Cycas circinalis: Megasporophyll lamina 75 to 100 millimeters long. Plants of India
* Cycas nathorstii: Megasporophyll lamina 40 to 70 millimeters long. Plants of Sri Lanka

## CYC31

* Cycas chamberlainii: Lateral spines on megasporophyll lamina over ten millimeters long.
* CYC33: Lateral spins on megasporophyll lamina less than 10 millimeters long.

## CYC32

* Cycas macrocarpa: Lateral teeth of megasporophyll over seven millimeters long.
* CYC34: Lateral teeth of megasporophyll less than seven millimeters long.

## CYC33

* Cycas riuminiana: Plants of the Philippines
* Cycas spherica: Plants of India

## CYC34

* Cycas apoa: Lamina lacking lateral spines
* CYC35: Lamina has distinct lateral spines or teeth.

## CYC35

* Cycas javana: Lamina thin and tapering toward the tip.
* CYC36: Lamina egg-shaped.

## CYC36

* Cycas inermis: Stems 1 to 4 meters tall; 8 to 14 centimeters in diameter; Petiole is 60 to 80 centimeters long.
* Cycas scratchleyana: Stems over 4 meters tall; 12 to 20 centimeters in diameter; Petiole is 20 to 70 centimeters long.

## CYC37

* CYC39: Lateral megasporophyll teeth large; Basal pinnae reducing to spines.
* CYC40: Lateral megasporophyll teeth small; Basal pinnae not reducing to spines.

## CYC38

* CYC41: Hypodermis present; Leaf edges recurved.
* CYC42: Hypodermis absent; Leaf edges flat.

## CYC39

* Cycas basaltica: Leaves are flat
* CYC67: Leaves are keeled

## CYC40

* CYC68: Pinnae edges flat or recurved; Pinnae more than five millimeters wide.
* CYC69: Pinnae rolled backward or downward; Pinnae less than five millimeters wide.

## CYC41

* CYC43: Hypodermis continuous; Leaves grey or blue.
* CYC44: Hypodermis interrupted; Leaves green.

## CYC42

* Cycas canalis: New leaves glaucous blue
* CYC70: New leaves green or bluish green

## CYC43

* CYC45: Leaves strongly glaucous; Male cones oval-shaped.
* CYC46: Leaves not glaucous, or only slightly; Male cones large and spherical.

## CYC44

* CYC47: Spines and/or bristles present on cataphylls
* CYC48: Spines and/or bristles not present on cataphylls

## CYC45

* CYC76: Pinnae edges rolled backward or downward; Pinnae less than four millimeters wide.
* CYC77: Pinnae edges flat or recurved, but not rolled backward or downward; Pinnae over four millimeters wide.

## CYC46

* Cycas angulata: Pinnae are less than six millimeters wide.
* Cycas brunnea: Pinnae are over six millimeters wide.

## CYC47

* Cycas megacarpa: Leaves are keeled over 135 degrees.
* CYC75: Leaves are flat, or at least keeled less than 135 degrees.

## CYC48

* CYC79: Cataphylls and crown densely orange and wooly.
* CYC80: Cataphylls and crown gray or white.

## CYC49

* Cycas hainanensis: Seeds relatively large
* CYC51: Seeds relatively small

## CYC50

* Cycas taiwaniana: Twelve to thirty leaves in crown
* Cycas tanqingii: Four to seven leaves in crown

## CYC51

* CYC52: Plants relatively large
* CYC53: Plants relatively small

## CYC52

* Cycas tropophylla: Leaves keeled
* Cycas ferrunginea: Leaves flat

## CYC53

* Cycas chanfjiangensis
* Cycas miquelii

## CYC54

* CYC56: Microsporophylls coming to a short, abrupt point.
* CYC57: Microsporophylls rounded

## CYC55

* CYC58: Pinnae dichotomously divided two to three times.
* CYC59: Pinnae pinnately divided and dichotomously divided more than three times.

## CYC56

unfinished
* Cycas chevalieri:
* Cycas fugax:
* Cycas hoabinhensis:

## CYC57

* Cycas diannanensis: Cataphylls long and rigid.
* CYC60: Cataphylls short and soft.

## CYC58

* Cycas micholitzii: Leaves 110 to 240 centimeters long and moderately keeled (inserted at 90-120 degrees on rachis)
* Cycas multifrondis: Leaves 200 to 500 centimeters long and flat to slightly keeled (inserted at 120-180 degrees on rachis)

## CYC59

* Cycas debaoensis: Megasporophylls are 12-14 centimeters long
* Cycas multipinnata: Megasporophylls are 7-11 centimeters long

## CYC60

* CYC61: Male cones are small and narrow
* CYC62: Male cones are large

## CYC61

unfinished
* Cycas balansae
* Cycas brachycantha
* Cycas simplicipinna

## CYC62

unfinished
* Cycas collina
* Cycas dolichophylla
* Cycas guizhouensis
* Cycas segmentifida
* Cycas yunnanensis

## CYC63

* Cycas pectinata: Has long apical microsporophyll spine.
* CYC65: Has a short apical microsporophyll spine.

## CYC64

* Cycas nongnoochiae: Male cones small
* CYC66: Male cones medium to small.

## CYC65

unfinished
* Cycas clivicola
* Cycas elongata
* Cycas tansachana

## CYC66

unfinished
* Cycas condaoensis
* Cycas pachypoda

## CYC67

* Cycas furfuracea: Pinnae margins flat or recurved; pinnae are over five millimeters wide
* Cycas pruinosa: Pinnae margins are rolled backward or downward; pinnae are less than five millimeters wide.

## CYC68

* Cycas arnhemica: New growth with mostly brown or orange trichomes.
* Cycas maconochiei: New growth with mostly white or grey trichomes.

## CYC69

* Cycas arenicola: Pinnae four to seven millimeters wide; 180-270 pinnae present.
* Cycas calcicola: Pinnae two to four millimeters wide; 200-400 pinnae present.

## CYC70

* Cycas conferta: Pinnae the same color throughout and have stomata on upper and lower surfaces.
* CYC71: Pinnae more or less different colors throughout and only have stomata on one side.

## CYC71

* CYC72: Cataphylls pale brown and hairy
* CYC73: Cataphylls orange and wooly

## CYC72

* Cycas orientis: Midrib more prominent below than above.
* CYC74: Midrib equally prominent above and below.

## CYC73

* Cycas armstrongii: Stems less than twelve centimeters in diameter.
* Cycas lane-poolei: Stems over twelve centimeters in diameter.

## CYC74

unfinished
* Cycas papuana
* Cycas xipholepis

## CYC75

* Cycas media: Pinnae are less than nine millimeters wide; Cataphylls are persistent.
* Cycas silvestris: Pinnae are over nine millimeters wide; Cataphylls are deciduous.

## CYC76

* Cycas cairnsiana: Cataphylls soft and short.
* Cycas desolata: Cataphylls sharply pointed and long.

## CYC77

* Cycas couttsiana: Main growth mostly gray or white trichomes.
* CYC78: Main growth mostly orange or brown trichomes.

## CYC78

* Cycas ophiolitica: Pinnae six to eight millimeters wide; Leaves keeled at 80-120 degrees.
* Cycas platyphylla: Pinnae four to six millimeters wide; Leaves keeled at 45-60 degrees.

## CYC79

* Cycas campestris: Lateral spines of megasporophyll lamina over 8 millimeters long.
* CYC81: Lateral spines of megasporophyll lamina less than 8 millimeters long

## CYC80

* Cycas semota: Megasporophylls 18 to 25 centimeters long; Apex 15 to 35 millimeters wide and not dilated.
* Cycas tuckeri: Megasporophylls 10 to 15 centimeters long; Apex 35 to 50 millimeters wide and dilated.

## CYC81

unfinished
* Cycas badensis
* Cycas schumanniana
* Cycas yorkiana