Dichotomous Key/Cycas

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Cycas
KingdomPlantae
DivisionCycadophyta
ClassCycadopsida
OrderCycadales

Information related to Cycas

Wikipedia • Wikispecies •

Wikicommons

Key to the species of Cycas:

Cycas

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

CYC1

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

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

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

CYC19

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

CYC24

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

CYC25

CYC26

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

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

CYC34

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

CYC35

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

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

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

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

CYC50

CYC51

  • CYC52: Plants relatively large
  • CYC53: Plants relatively small

CYC52

CYC53

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

CYC57

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

CYC60

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

CYC61

unfinished

CYC62

unfinished

CYC63

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

CYC64

CYC65

unfinished

CYC66

unfinished

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

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

CYC74

unfinished

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

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

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