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1 Pistils in a single whorl, borne on a flat receptacle; stamens 6; inflorescence compound, many of the primary nodes bearing whorled branches which in turn bear whorled branches or whorled flowers |
1 Pistils spiraled in several to many whorls, borne on a globose receptacle; stamens 6-many; inflorescence either racemose (or in some species of both Echinodorus and Sagittaria somewhat compound, with the lowermost node or two bearing branches which in turn bear whorled flowers) or umbellate ( Hydrocleys). |
..2 Scape septate; fruits follicles |
..2 Scape not septate; fruits achenes. |
....3 Achenes flattened, with winged margins and often also with irregular corky ornamentations on the faces; flower whorls subtended by 3 bracts, with no additional bracteoles |
....3 Achenes turgid, with ribs or ridges; flower whorls subtended by 3 bracts and additional bracteoles. |
......4 Leaf blades 5-20 cm long, 3-15 cm wide; achenes (pistils) 45-250 per head; stamens ca. 21; petals 6-12 mm long, scapes 20-120 cm tall, erect or arching/reclining |
......4 Leaf blades 1-3 cm long, 0.2-2 cm wide; achenes (pistils) 10-20 per head; stamens 6 or 9; petals 1-3 mm long; scapes 5-10 cm tall, erect |
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..2 Leaf blades oval in shape, ca. 1.5-2× as long as wide, at maturity floating on the water’s surface; underwater portions of fresh plant coated in transparent mucilage |
..2 Leaf blades orbicular in shape, ca. 1× as long as wide, at maturity floating on the water’s surface, emersed, or submersed; underwater portions of fresh plant not mucilaginous (though possibly with green algae, etc.). |
....3 Leaves small, < 8 cm in diameter, at maturity emersed or submersed |
....3 Leaves large, > 20 cm in diameter, at maturity floating on the water’s surface or emersed |
1 Leaves not peltate, the petiole attached at a cuneate, cordate, or sagittate base. |
......4 Leaf blades cuneate, rounded, or truncate at the base. |
........5 Basal leaves lanceolate, 3-6 mm long |
........5 Basal leaves variously shaped, > 10 mm long. |
..........6 Main veins palmate from the leaf base and also diverging from the midvein, the secondary and tertiary veins then reticulating; inflorescence a spike; [Eudicots] |
..........6 Main veins either parallel or palmate from the leaf base with cross-veins at nearly right angles to the main veins; inflorescence either a diffuse raceme or panicle of white flowers, or a linear spadix of tightly packed golden-yellow flowers; [Monocots]. |
............ 7 Inflorescence diffuse, a raceme or panicle with whorled branches or pedicels, the flowers widely spaced and white; leaves green, “wettable” |
............ 7 Inflorescence tightly packed with flowers, an elongate, golden yellow spadix; leaves blue-green, “unwettable” |
......4 Leaf blades cordate or sagittate at the base. |
............ ..8 Leaf blades sagittate, the two lobes distinctly acute; leaf apex acute; leaf blade 1.3-3× as long as wide |
............ ..8 Leaf blades cordate, the two lobes rounded or sub-acute; leaf apex rounded or apiculate; leaf blade 0.8-8× as long as wide. |
............ ....9 Leaf blade margins serrate, dentate, and/or incised |
............ ....9 Leaf blade margins entire or obscurely crenate. |
............ ......10 Flowers 4-5-merous (sepals 4-5, petals 4-5, stamens 4-5); [Eudicots] |
............ ........11 Leaves emersed or submersed, on stout, stiff petioles (the submersed and winter leaves cuneate-based and lanceolate); flowers 4-merous (sepals 4, petals 4, stamens 4); inflorescence a spike |
............ ........11 Leaves floating, on slender, flexuous petioles (all leaves cordate-based); flowers 5-merous (sepals 5, petals 5, stamens 5); inflorescence an umbel |
............ ......10 Flowers 3-merous or many (>5-) -merous; [Basal Angiosperms or Monocots]. |
............ ..........12 Perianth parts numerous (usually showing differentiation into sepals and petals, though often with some intergradation), borne in a spiral; stamens numerous; leaves usually > 10 cm long or > 10 cm wide, or both (a few northern species of Nymphaea with leaves as small as 2.5 cm × 2.5 cm); [Basal Angiosperms] |
............ ..........12 Perianth parts 3-6 (either differentiated or not into sepals and petals); stamens either 3, or 9-12 (-18), or >20; leaves 1-10 cm long, 1-10 cm wide; [Monocots]. |
............ ............ 13 Perianth strongly differentiated, the 3 sepals green, leathery, and persistent, the 3 petals yellow or white, delicate, deciduous; stamens 20 or more |
............ ............ 13 Perianth not strongly differentiated, the sepals petaloid and similar in texture and color to the petals; stamens 10 or fewer. |
............ ............ ..14 Flowers unisexual, white, the sepals and petals separate; stamens 3, 6, 9, 12, 15, or 18; leaves either with a central area of spongiform cells (most easily seen on the lower leaf surface) ( Limnobium), or without spongiform cells ( Ottelia) |
............ ............ ..14 Flowers bisexual, white to blue, the perianth segments united below into a perianth tube 3-45 mm long; stamens 3; leaves lacking a central area of spongiform cells |