| Class: | angiosperms |
| Order: | Alismatales |
| Family: | Potamogetonaceae |
| Name acc. to: | APGII |
| Herbar: | list records    |
| Description: | Aquatic plants with submerged stems, leaves floating or submerged. Leaves alternate rarely in verticils by 3. Flowers bisexual in spicate inflorescences; stamens by 4 or 1; pistils 2-5. Fruits sessile. |
| Tax. Comments: | See also Zannichelliaceae. |
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| genus: 1 |
| species: 18 |
| Habit (i)general appearance of a plant | |
| Growth form: (i)Herb, shrub, tree or climber. | herb (i)Herbaceous, erect plant, up to 2m high, mostly with a leafy shoot; if perennial, shoots die to the ground each season, shoots are not woody
example: Artemisia pectinata 
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| Parasite status: (i)Is the plant a half- or full parasite? | no parasite/saprophyte (i)Plant fully autonomous, leaves with chlorophyll
example: Most plants, Ranunculus
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| Water or terrestrial plant: (i)Where do the plants grow? | water or swamp plant
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| Leaf (i)expanded, usually photosynthetic organ of a plant (including phylloclades) | |
| Leaf development: (i)Structure and development of leaves. | flattened blade (i)Cross-section of lamina flat, plain
common leaf (i)Green, often divided in blade and petiole
example: Cotoneaster
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| Leaf margin: (i)Structure of leaf margin (or that of a leaflet in case of compound leaves). Attention: Here we ask for the leaf margin, defined as all those dissections that separate the leaf for less than one third of its length or width, whatever is smaller. To be worked out: how to handle margin of pinnate leaves? | entire (i)Plain margin, not toothed
example: Iris 
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| Leaf veination: (i)Arrangement of the main veins of a leaf. | parallel (i)Most veins arranged parallel to the length of leaf, mostly no pronounced main vein (usually in elongate to linear leaves)
example: Most Monocotyledonae, Plantago, Veratrum, a lot of Caryophyllaceae looks like that. 
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| Flower (i)reproductive portion of the plant, consisting of sepals, petals, stamens, and pistils | |
| Flower appearance and pollination: (i)General appearance of the flower. | not attractive, wind-pollinated or some water plants (i)Small, colourless or green flowers
example: Betula, grasslike plants: Carex, Setaria, Juncus
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| Flower colour: (i)Attention: assess colour of the most colourful parts of the flower, but not of the stamens; be aware of single plants with a mutation (mostly white) on flower colour. | greenish (i)petals absent or not distinctly different from colours of leaves, only stigmas (white) or anthers (yellow) may differ in color
example: Chenopodium, Triglochin
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| Perianth arrangement: (i)Attention: in some plants, flowers may be dimorphic in different ways (dioecious or gynodioecious). If flowers vary, record the characters of the most showy flowers. | absent or strongly reduced (i)No perianth leaves ensheathing stamen and/or carpels
example: Callitriche 
simple, similar (i)Only one type of perianth leaves (tepals)
example: Tulipa 
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| Diameter of flower: (i)Diameter of flower or flower head. | to 5 mm (i)
example: Aruncus
from 5 mm to 10 mm (i)
example: Stellaria
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| Petal / Tepal number: (i)Number of petal leaves (inner perianth leaves, usually coloured). | none or reduced (i)But green sepals may exist
example: Thalictrum
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| Spur: (i)A hollow, slender, sac-like appendage of the perianth leaves, storing nectar. | no spur (i)Flower without appendage
example: Peganum
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| Stamen fusion: (i)To which degree are the stamens fused? Attention: Whereas the pollen sacs itself are often free., their stalks (filaments) may be fused. Here, we count them as fused if they are together over at least one thirth of their length. | free (i)Stamens with separate bases
example: Malus
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| Ovary position: (i)For entirely or partly fused carpels, describe their position in relation to the insertion point of perianth leaves (best done by doing a longitudinal section of a flower). | superior (hypogynous) (i)Base of carpels attached above insertion point of perianth leaves, carpels free or fused
example: Delphinium, Anemone  
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| Inflorescence (i)flowering part of a plant, describes the arrangement of the flowers on the flowering axis | |
| Appearance: (i)Outer look of the inflorescence. | terminal (i)Inflorescence is the highest point of the plant and may consist of a single flower only
example: Cypripedium, Rhaponticum, Ligularia sibirica, Echinops
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| Inflorescence type: (i)Types of inflorescence. Attention: We here ask for the botanical nomenclature of inflorescences, which is sufficiently complicated. Tick only, if you are certain, or tick all inflorescence types that appear similar of these of the plant in question. | spike (spadix) (i)All flowers sessile and crowded along a main axis, there may be several spikes on a shoot; sometimes axis thickened (spadix)
example: Plantago, Carex vesicaria, Vicia, Typha (spadix)  
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| Root / shoot below ground (i)plant part below ground (in most cases), including below ground shoots, without leaves | |
| Root type: (i)Organisation of the roots. | homorhizous (i)Many equal roots
example: Monocotyledonae  inherited by order Alismatales: homorhizous
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