Dichotomous Key/Cycadophyta

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Dichotomous Key
CycadKingSago.jpg
Kingdom Plantae
Division Cycadophyta
Class Cycadopsida
Order Cycadales

This is the key to species of Cycadophyta.

Key to the species of Cycadophyta[edit]

  • Cycas: Pinnae have a single midrib and lack secondary veins
  • 1: Pinnae have more than one vein

1[edit]

  • Bowenia: Leaves are bipinnate
  • 2: Leaves are once-pinnate

2[edit]

3[edit]

  • 4: Sporophylls in vertical rows
  • 5: Sporophylls in spirals

4[edit]

  • Chigua: Pinnae have an obvious midrib
  • 6: Pinnae lack an obvious midrib

5[edit]

  • Lepidozamia: Pinnae attach to midline of rachis
  • 8: Pinnae attach to sides of rachis

6[edit]

  • Microcycas calocoma: Leaves are square or broad at the end.
  • 7: Leaves are not broad or square at the end.

7[edit]

8[edit]

  • Macrozamia: Sporophylls have a sharp upturned spine
  • 9: Sporophylls lack a sharp upturned spine.

9[edit]

  • Dioon: Sporophylls have flat overlapping tips.
  • Encephalartos: Sporophyll tips do not overlap

Bowenia[edit]

  • Bowenia spectabilis: One to ten leaf bearing branches; Largest leaves have ten or less pinnae; Pinnules usually entire, or nearly so.
  • Bowenia serrulata: Five to twenty leaf bearing branches; Largest leaves have more than ten pinnae; Pinnules toothed or lobed.

Ceratozamia[edit]

unfinished

Chigua[edit]

  • Chigua bernalii: Pinnae are over 30 centimeters long and less than 20 millimeters wide.
  • Chigua restrepoi: Pinnae are less than 30 centimeters long and over 20 millimeters wide.

Cycas[edit]

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

CYC1[edit]

CYC2[edit]

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

CYC3[edit]

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

CYC4[edit]

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

CYC5[edit]

CYC6[edit]

  • 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[edit]

  • 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[edit]

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

CYC9[edit]

  • 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[edit]

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

CYC11[edit]

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

CYC12[edit]

CYC13[edit]

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

CYC14[edit]

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

CYC15[edit]

  • CYC54: Pinnae simple
  • CYC55: Pinnae dichotomously divided

CYC16[edit]

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

CYC17[edit]

  • 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[edit]

CYC19[edit]

  • CYC16: Phelloderm smooth
  • CYC18: Phelloderm corky

CYC20[edit]

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

CYC21[edit]

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

CYC22[edit]

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

CYC23[edit]

CYC24[edit]

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

CYC25[edit]

CYC26[edit]

CYC27[edit]

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

CYC28[edit]

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

CYC29[edit]

CYC30[edit]

  • 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[edit]

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

CYC32[edit]

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

CYC33[edit]

CYC34[edit]

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

CYC35[edit]

CYC36[edit]

  • 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[edit]

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

CYC38[edit]

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

CYC39[edit]

CYC40[edit]

  • 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[edit]

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

CYC42[edit]

CYC43[edit]

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

CYC44[edit]

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

CYC45[edit]

  • 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[edit]

CYC47[edit]

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

CYC48[edit]

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

CYC49[edit]

CYC50[edit]

CYC51[edit]

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

CYC52[edit]

CYC53[edit]

CYC54[edit]

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

CYC55[edit]

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

CYC56[edit]

unfinished

CYC57[edit]

CYC58[edit]

  • 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[edit]

CYC60[edit]

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

CYC61[edit]

unfinished

CYC62[edit]

unfinished

CYC63[edit]

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

CYC64[edit]

CYC65[edit]

unfinished

CYC66[edit]

unfinished

CYC67[edit]

  • 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[edit]

CYC69[edit]

  • 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[edit]

  • 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[edit]

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

CYC72[edit]

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

CYC73[edit]

CYC74[edit]

unfinished

CYC75[edit]

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

CYC76[edit]

CYC77[edit]

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

CYC78[edit]

  • 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[edit]

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

CYC80[edit]

  • 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[edit]

unfinished

Dioon[edit]

  • DIO1: Leaflets straight
  • DIO2: Leaflets curved or hooked

DIO1[edit]

  • DIO3: Leaflets less than fifteen millimeters wide.
  • DIO4: Leaflets over fifteen millimeters wide.

DIO2[edit]

DIO3[edit]

DIO4[edit]

DIO5[edit]

  • DIO7: Leaflets inserted at 90 degrees to rachis.
  • DIO8: Leaflets inserted at 45 degrees or less to rachis.

DIO6[edit]

DIO7[edit]

  • Dioon holmgrenii: Leaflets seven to nine millimeters wide; Leaflets do not overlap.
  • Dioon merolae: Leaflets en to twelve millimeters wide; Leaflets overlap.

DIO8[edit]

  • Dioon caputoi: Leaflets less than five millimeters wide; Leaflets flat and do not overlap.
  • DIO9: Leaflets over five millimeters wide; Leaflets keeled and overlap.

DIO9[edit]

Encephalartos[edit]

unfinished

Lepidozamia[edit]

  • Lepidozamia hopei: Pinnae have fifteen to thirty parallel veins; Broadest pinnae fifteen to thirty millimeters wide.
  • Lepidozamia peroffskyana: Pinnae have five to fifteen parallel veins; Broadest pinnae five to fifteen millimeters wide.

Macrozamia[edit]

unfinished

Zamia[edit]

unfinished

References[edit]

  • Jones, David L. Cycads of the World: Ancient Plants in Today's Landscape. Smithsonian Books: Reed, Sydney, 2002.
  • Walters, T. and Osborne, R. 2004. Cycad Classification Concepts and Recommendations. Wallingford UK: CABI Publishing.
  • Whitelock, Loran. The Cycads. Portland: Timber Press, 2002.