1:(A)
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Reproductive organs (flowers) unisexual, often subtended by bract-like structures, rarely by 2 or 4 free or connate, opposite bracteoles (Gnetales), but true perianth absent. Stamens (micro-sporophylls) more or less developed, several to many together (pollen cones or micro-sporangia), each with 2-many, rarely 1, anthers (pollen sacs) Carpels (macro-sporophylls) not connate into a closed ovary. Ovules naked, rarely enclosed in a utricle, atropous or anatropous, sessile, 1-several together, subtended by a bract; bracts usually aggregated into cones. Seeds exposed, or enclosed, either by the bracts ('cone-scales') or by parts of the seed-bearing structure ('epimatia'), these usually woody or leathery, sometimes fleshy and pseudo-carp berry- or drupe-like, rarely seed more or less enclosed in a basally attached, fleshy aril. Stem woody. (Gymnospermae)
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1:(B)
Flowers unisexual or bisexual. True perianth usually present. Anthers usually on a filament. Ovules completely enclosed¹ by the ovary. Fruit very rarely cone-like. Seeds completely enclosed by the fruit, which may dehisce at maturity. Style usually present. (Angiospermae) ¹incomlpetly so in Degeneriaceae, Nelumbo, Platanus, Resedaceae.
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2:(A)
previous:A
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Flowers usually in branched and very compound inflorescence; at least the male ones with a pseudo-perianth of 2 opposite, free and/ or 2 more or less connate bracteoles. Resin absent. Leaves opposite, simple, sometimes scale-like. Ovule enclosed in a utricle, atropous with a style-like, elongated integument. Seeds nut-like, en closed by fleshy bracts in a cone or a drupe- or berry-like syncarp. (Gnetales)
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2:(B)
Flowers solitary, or in capitules, or in spikes, or in cones. Pseudo-perianth absent, flowers usually subtended by bract-like scales.
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3:(A)
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Shrubs, trees, or woody climbers with well-developed trunks. Leaves more than 2, scale-like or well-developed, pinninerved.
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3:(B)
Woody perennial with a very stout, truncate, subterraneous stem, apically bi-lobed, each lobe with a strap-shaped, parallel-nerved leaf, which may tear to the base. Male flowers with 2 free and 2 connate bracteoles, 6 micro-sporophylls at base connate into a tube and a pistillode. Deserts of S.W. Africa.
4:(A)
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Virgate shrubs. Leaves small, scale-like, connate. Flowers in cones. Male flowers with 2 connate bracteoles and 2-8 micro-sporophylls on an androphore. Warm temperate Eurasia, N. and S. America.
4:(B)
Usually climbing shrubs, rarely trees. Leaves well-developed, free, pinninerved. Flowers whorled in spikes. Male flowers with 2 bracteoles connate into a tube. Micro-sporophylis 1 or 2 on an androphore. Tropics.
5:(A)
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Bole tuberous or columnar, simple, rarely branched, then usually only at the apex and branches not originating from axillary buds. Sap slimy. Leaves large, palm-like, usually accompanied by scales, terminally tufted. Pollen sacs many (25 or more) per microsporophyll, in clusters of 2-6. (Cycadales)
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5:(B)
Bole usually branched, branches slender, originating from axillary buds. Sap usually resinous. Leaves moderately sized to small, not palm-like, simple, entire or fan-shaped. Pollen sacs up to 15 per micro- , sometimes in 2 rows, never in clusters.
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6:(A)
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Leaflets either with a midrib and lateral nerves, or without a midrib and nerves parallel. Ovules 2 per bract, floral axis not growing through the female pseudo-flower.
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6:(B)
Leaflets with a midrib, lateral nerves absent. Ovules 4-8, rarely 2 per bract. Floral axis growing through the female flower (i.e. the whorls of ovule-bearing bracts)
7:(A)
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Leaflets parallel-nerved, nerves straight or wavy, simple or forked at base.
7:(B)
Leaflets pinninerved, midrib distinct, lateral nerves parallel, forked. Leaflets convolute in bud. S. Africa.
8:(A)
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Leaves usually with a single midrib, sometimes with additional parallel veins, or a dichotomous venation, rarely with 2 unbranched veins, then leaves in whorls of 16-30, each with a small bract at base (Sciadopitys); apex rounded to acute. Ovules either subtended by bracts, or surrounded by sterile parts of a modified shoot structure, almost always by both in a compound structure.
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8:(B)
Leaves at base with 2 nerves, which branch dichotomously, midrib absent, apex usually 2-lobed. Ovules usually 2, on a long stalk, each with a cupule at base. Long and short shoots present. Leaves alternate, long-petioled, broad, fan-shaped. Female inflorescence in the axils of leaf-like bracts. (Ginkgoales)
9:(A)
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Seed either with a fleshy outer surface, or partly to completely enclosed by a fleshy aril, then drupe-like. Leaves with a single vein. Ovules atropous, at least partly exposed. (Taxales)
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9:(B)
Seed rarely fleshy, then ovule anatropous. Fleshy aril absent, but other fleshy structures sometimes present. Leaves with a single vein, or with a midrib and additional parallel veins. Ovules atropous or anatropous. (Coniferales)
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10:(A)
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Ovule 1, terminal on a specialised shoot, subtended by several decussate bracts. Seed at least partly enclosed by a fleshy aril, when completely so drupe-like. Pollen cones and ovule-bearing structures sometimes 2- more together on specialised fertile shoots.
10:(B)
Ovules 2 per bract, axillary; bracts in cone-like inflorescences. Seed with a fleshy outer surface. Pollen structures compound and reduced in cones in the axils of leaves of the preceding year.
11:(A)
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Ovule 1 per bract. Seed not winged, each surrounded by a fleshy bract, then drupe-like, or bracts forming a fleshy syncarp, or both. Pollen sacs 2 per micro-sporophyll, inverted.
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11:(B)
Ovules 1-several per bract. Seed usually winged. Syncarp usually woody, rarely fleshy (Juniperus) Pollen sacs 2-more per microsporophyll.
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12:(A)
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Leaves well-developed or scale-like, entire, phylloclades absent. Ovules usually anatropous, either with a thin cup-like epimatium at base, or enclosed by a leathery or fleshy one, then drupe-like, rarely atropous, then epimatium absent (Microstrobos) Pseudo-carp drupe-like.
12:(B)
Leaves inconspicuous, scale-like, phylloclades present, flagellate, lobed, or dentate. Ovule atropous with a thin epimatium or aril at base. Pseudo-carp a fleshy cone. (Phyllocladaceae)
13:(A)
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Pollen sacs usually 3-more per micro-sporophyll, rarely 2. Ovules 1-more per bract, atropous or anatropous. Seed usually with 1-3 wings. Bract adaxially inappendiculate, or with a transverse ridge, or with 1, rarely 2 scales.
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13:(B)
Pollen sacs 2 per micro-sporophyll. Ovules 2 per bract, anatropous. Bracts paired, the two more or less free from each other, the outer usually small and thin, the enlarging and finally woody. Leaves solitary or paired or tufted on specialised short shoots with which they are decumbent. Female bracts in a spiral.
14:(A)
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Leaves usually with 1 midrib, rarely with 2 unbranched main nerves, then in whorls of 16-30 (Sciadopitys) Female bracts usually not deciduous, if so, then seeds 2-more per bract and bracts without wing-like margins. Ovules usually more than 1 per bract, atropous or anatropous. Seeds usually with 1 - 3 wings.
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14:(B)
Leaves usually with both a midrib and several to many parallel veins. Female bracts usually deciduous with adnate, not winged seeds and with winged margins, if not deciduous, seed with 1 or 2 wings. Female bracts in a spiral.
15:(A)
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Leaves and female bracts decussate or 3 or 4 in a whorl, never distichous. ovules atropous, 1-several per bract. Seed not winged or with 1-3 wings.
15:(B)
Leaves and female bracts usually in a spiral, distichous or not; leaves rarely opposite on decussate, specialised branchless with which they are decumbent (Metasequoia), or in whorls of 16-30 (Sciadopitys) Ovules atropous or anatropous. Seed with 1-3 wings.
Sciadopityaceae
16:(A)
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Stem in transverse section with scattered vascular bundles. Leaves usually parallel-nerved, rarely reticulately so, or absent¹, usually narrow, undivided, entire, sometimes with adaxial appendages. Flowers usually 3-merous. Pollen usually monocolpate. Cotyledon usually 1, rarely absent. (Monocotyledones) ¹ Reticulately nerved in many Araceae, Dioscoreaceae, Musaceae, Orchidaceae, Taccaceae, some Liliaceae s.l.; absent in Corsiaceae, Geosiridaceae, Lemnaceae, Triuridaceae, and some Liliaceae s.l., Burmanniaceae, Cyperaceae, Juncaceae, Orchidaceae, Restionaceae.
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16:(B)
Stem in transverse section usually with the vascular bundles in a ring. Leaves usually reticulately nerved, rarely both narrow and en tire, or absent. Flowers usually 4- or 5-merous. Pollen rarely monocolpate. Cotyledons usually 2¹ rarely only 1,² or absent³.(Dicotyledones) ¹ Cotyledons 3 or 4; whorled in Degeneriaceae, Calycanthaceae (Idiospermum); and Opiliaceae.
² e.g. in some Portulacaceae (Claytonia), Gesneriaceae (Monophyllaea), Primulaceae (Cyclamen), Cruciferae (Dentaria), Ranunculaceae (Ficaria), Papaveraceae (Corydalis).
³ In the seedlings of the 'Barringtonia-', 'Garcinia-' and 'Orobanche-' type (cf. De Vogel, Seedlings of Dicotyledons, 1979).
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