Jepson eFlora Family Key to Group 2

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Citation for the whole project: Jepson Flora Project (eds.) . Jepson eFlora, https://ucjeps.berkeley.edu/eflora/ [accessed on ]

Group 2: Aquatic plants in vegetative condition; sporangia, sporangium cases, seeds, cones, or cone-like structures 0 or not readily apparent

1. Plant body consisting of a jointed, hollow-stemmed central axis and 

whorled 

Arranged in groups of three or more at nodes or positions along an axis (e.g., three leaves per node).

branches; leaves reduced to whorled scales; plant emergent ..... EQUISETACEAE {G3}

1' Plant body various, but not consisting of a jointed, hollow-stemmed central axis and 

whorled 

Arranged in groups of three or more at nodes or positions along an axis (e.g., three leaves per node).

branches; leaves various, but not whorled scales; plant free-floating, emergent, or submersed

2. Plant raft-like, free-floating on water surface or stranded along shore or in drying bottom sediments, breaking apart into individuals or small clumps

3. Individual plant generally 0.4–30 mm in length or diam, sometimes not differentiated into leaves and stems; roots unbranched

4. Plant body spheric to disk-shaped or 

oblong 

Longer than wide, with nearly parallel sides; wider than linear.

, not differentiated into stems and leaves ..... ARACEAE (3) {G6,8,13,15}

4' Plant body differentiated into a short, often branched stem with small, minutely velvety-papillate, scale-like leaves ..... AZOLLACEAE {G3}

3' Individual plant often >> 30 mm, differentiated into leaves and stems; roots generally branched (0 in Salviniaceae, with finely dissected, root-like submersed leaves)

5. Leaf blades glossy green, glabrous, finely parallel-veined; 

petioles 

Leaf stalk, connecting leaf blade to stem; sometimes more or less indistinct.

often enlarged, forming gas-filled floats ..... PONTEDERIACEAE (Eichhornia)

5' Leaf blades light to dark green or ± purple, velvety-hairy, ± palmately or obscurely veined, 

sessile 

Without a petiole, peduncle, pedicel, or other kind of stalk.

, lacking floats, ± palmately or obscurely veined

6. Leaves in floating 

rosettes 

A radiating cluster of leaves generally at or near ground level.

, evidently ± palmately veined ..... ARACEAE ([Pistia]) {G15}

6' Leaves in whorls of 3, 2 floating, 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

, obscurely veined, the 3rd submersed, finely dissected, root-like ..... SALVINIACEAE {G3}

2' Plant generally anchored in bottom sediments or, if free-floating, most of plant body below water surface or not readily breaking apart — rhizomes or stolons present or 0, sometimes elongated

7. Leaf 

peltate 

With the stalk attached toward the middle, not at a margin, of a flat structure such as an indusium, scale, or leaf.

, 

cordate 

Heart-shaped; often pertaining to a leaf in which the blade base on both sides of the petiole is rounded and convex.

, 

sagittate 

Arrowhead-shaped, with two basal lobes oriented nearly parallel to the long axis.

, or deeply notched

8. Leaf 

peltate 

With the stalk attached toward the middle, not at a margin, of a flat structure such as an indusium, scale, or leaf.

9. Submersed parts not gelatinous; 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 blades generally emergent ..... ARALIACEAE (Hydrocotyle) (2) {G14,21}

9' Submersed parts gelatinous; 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 blades floating ..... CABOMBACEAE (Brasenia)

8' Leaf 

sagittate 

Arrowhead-shaped, with two basal lobes oriented nearly parallel to the long axis.

or 

cordate 

Heart-shaped; often pertaining to a leaf in which the blade base on both sides of the petiole is rounded and convex.

to 

ovate 

Egg-shaped (i.e., widest below the middle) in two dimensions (i.e., in one plane), as a leaf.

or ± round, the base shallowly to deeply notched

10. Leaf blades pinnately veined; 

petioles 

Leaf stalk, connecting leaf blade to stem; sometimes more or less indistinct.

long, stout; 

rhizome 

1. In seed plants, stem that is often elongate, more or less horizontal, usually underground; distinguished from roots by bearing of leaves, leaf scars, axillary buds, etc. 2. In ferns, stem that is located underground, embedded in leaf litter, on rocks or in rock crevices, or on trees or tree branches, often scaly or hairy; distinguished from roots by bearing of fronds (roots rarely bear fronds), and their greater diameter.

stout

11. Leaf 

sagittate 

Arrowhead-shaped, with two basal lobes oriented nearly parallel to the long axis.

; 

rhizome 

1. In seed plants, stem that is often elongate, more or less horizontal, usually underground; distinguished from roots by bearing of leaves, leaf scars, axillary buds, etc. 2. In ferns, stem that is located underground, embedded in leaf litter, on rocks or in rock crevices, or on trees or tree branches, often scaly or hairy; distinguished from roots by bearing of fronds (roots rarely bear fronds), and their greater diameter.

± vertical ..... ARACEAE ([Peltandra]) (2)

11' Leaf 

ovate 

Egg-shaped (i.e., widest below the middle) in two dimensions (i.e., in one plane), as a leaf.

to round; 

rhizome 

1. In seed plants, stem that is often elongate, more or less horizontal, usually underground; distinguished from roots by bearing of leaves, leaf scars, axillary buds, etc. 2. In ferns, stem that is located underground, embedded in leaf litter, on rocks or in rock crevices, or on trees or tree branches, often scaly or hairy; distinguished from roots by bearing of fronds (roots rarely bear fronds), and their greater diameter.

horizontal ..... NYMPHAEACEAE

10' Leaf blades ± palmately veined; 

petioles 

Leaf stalk, connecting leaf blade to stem; sometimes more or less indistinct.

long or short, slender or stout; 

rhizome 

1. In seed plants, stem that is often elongate, more or less horizontal, usually underground; distinguished from roots by bearing of leaves, leaf scars, axillary buds, etc. 2. In ferns, stem that is located underground, embedded in leaf litter, on rocks or in rock crevices, or on trees or tree branches, often scaly or hairy; distinguished from roots by bearing of fronds (roots rarely bear fronds), and their greater diameter.

, if present, slender

12. Leaf blades palmately lobed, never 

sagittate 

Arrowhead-shaped, with two basal lobes oriented nearly parallel to the long axis.

, the 

lobes 

1. A major expansion or bulge, such as on the margin of a leaf, sepal, or petal, or on the surface of an ovary. 2. The free tips of otherwise fused structures, such as sepals or petals; larger than teeth.

often toothed — veinlets forming an irregular network ..... ARALIACEAE (Hydrocotyle) (2) {G14,21}

12' Leaf blades 

ovate 

Egg-shaped (i.e., widest below the middle) in two dimensions (i.e., in one plane), as a leaf.

to 

cordate 

Heart-shaped; often pertaining to a leaf in which the blade base on both sides of the petiole is rounded and convex.

or 

sagittate 

Arrowhead-shaped, with two basal lobes oriented nearly parallel to the long axis.

, 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

13. Palmate veins 3 — smaller veins parallel, extending from main veins toward 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 margin ..... ARACEAE ([Peltandra]) (2)

13' Palmate veins generally 5–13+

14. Stipules 1–6 cm ..... PONTEDERIACEAE (Heteranthera limosa)

(3)

14' Stipules 0

15. Smaller veins passing like ladder-rungs between prominent main veins ..... ALISMATACEAE or HYDROCHARITACEAE

15' Smaller veins forming network ..... MENYANTHACEAE (Nymphoides) {G19}

7' Leaf not 

peltate 

With the stalk attached toward the middle, not at a margin, of a flat structure such as an indusium, scale, or leaf.

, 

cordate 

Heart-shaped; often pertaining to a leaf in which the blade base on both sides of the petiole is rounded and convex.

, 

sagittate 

Arrowhead-shaped, with two basal lobes oriented nearly parallel to the long axis.

, or deeply notched

16. Leaves all 

basal 

At or near the base of a plant or plant part. Especially said of leaves clustered near the ground or of a placenta confined to the base of an ovary.

or basal and cauline on a generally 

erect 

Upright; vertically oriented.

, generally emergent stem, sometimes from 

rhizome 

1. In seed plants, stem that is often elongate, more or less horizontal, usually underground; distinguished from roots by bearing of leaves, leaf scars, axillary buds, etc. 2. In ferns, stem that is located underground, embedded in leaf litter, on rocks or in rock crevices, or on trees or tree branches, often scaly or hairy; distinguished from roots by bearing of fronds (roots rarely bear fronds), and their greater diameter.

or corm-like base anchored in bottom sediments

17. Leaves petioled, with expanded blades

18. Leaf 

serrate 

Having margins with sharp, fine to coarse teeth generally pointing tipward, not outward; margins with such teeth on such primary teeth are doubly serrate.

or 

dentate 

Having margins with sharp, relatively coarse teeth pointing outward, not tipward.

to lobed or compound

19. Leaf 

palmate 

More than two structures or parts (e.g., veins, lobes, or leaflets) radiating from a common point in two dimensions (i.e., in one plane).

; leaflets 4 ..... MARSILEACEAE (Marsilea) (2) {G3}

19' Leaf toothed to pinnately lobed or 1–3-pinnate

20. Leaf bases sheathing; leaves, 

lobes 

1. A major expansion or bulge, such as on the margin of a leaf, sepal, or petal, or on the surface of an ovary. 2. The free tips of otherwise fused structures, such as sepals or petals; larger than teeth.

, or leaflets 

serrate 

Having margins with sharp, fine to coarse teeth generally pointing tipward, not outward; margins with such teeth on such primary teeth are doubly serrate.

to sharply dissected ..... APIACEAE (2) {G6,8,14,20,21}

20' Leaf bases not sheathing; 

lobes 

1. A major expansion or bulge, such as on the margin of a leaf, sepal, or petal, or on the surface of an ovary. 2. The free tips of otherwise fused structures, such as sepals or petals; larger than teeth.

or leaflets 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

or 

dentate 

Having margins with sharp, relatively coarse teeth pointing outward, not tipward.

with ± rounded teeth ..... BRASSICACEAE (Nasturtium, Rorippa)

18' Leaf 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

, 

simple 

Composed of a single part; undivided; unbranched.

21. Leaves generally << 1 cm wide ..... SCROPHULARIACEAE (Limosella) (2) {G18,19}

21' Leaves generally >= 1 cm wide, often much larger

22. Wider leaves floating ..... APONOGETONACEAE {G10}

22' Wider leaves generally emergent

23. Stipules 0 ..... ALISMATACEAE (2) {G10}

23' Stipules present, 1–6 cm ..... PONTEDERIACEAE (Heteranthera limosa)

(3)

17' Leaves 

sessile 

Without a petiole, peduncle, pedicel, or other kind of stalk.

, ± 

linear 

Elongate, with nearly parallel sides; narrower than elliptic or oblong.

or reduced to bladeless sheaths

24. Leaves vertically folded and attached "edge-on" to the stem, obviously 2-ranked ..... JUNCACEAE (Juncus) (4)

24' Leaves 

cylindric 

Elongate, with parallel sides and, at any point, round in transverse section.

, ± angled, flat, or reduced to bladeless sheaths, but not folded, not obviously 2-ranked

25. Leaves with flat blades or reduced to bladeless sheaths

26. Leaves bladeless or nearly so, composed mainly of a tubular 

sheath 

A surrounding or partially surrounding, often tubular structure or part of a structure, such as a leaf base in Apiaceae or Poaceae.

27. Stems ± triangular ..... CYPERACEAE (4) {G8,13}

27' Stems round, flattened, or several-angled

28. Leaf sheaths closed, forming a continuous cylinder around stem ..... CYPERACEAE (4) {G8,13}

28' Leaf sheaths open on one side, with overlapping margins ..... JUNCACEAE (Juncus) (4)

26' Leaves with ordinary flat blades and generally also ± tubular sheaths

29. Leaf 

blade 

Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped.

with a well-developed midvein or keel

30. Leaf sheaths closed, forming a continuous cylinder around stem; stem generally triangular; leaves 3-ranked ..... CYPERACEAE (4) {G8,13}

30' Leaf sheaths open on one side, with overlapping margins; stem round; leaves 2-ranked ..... TYPHACEAE (Sparganium) (3) {G6,8,13}

29' Leaf 

blade 

Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped.

flat or rounded on back, lacking a prominent midvein or keel

31. Annual; leaves all 

basal 

At or near the base of a plant or plant part. Especially said of leaves clustered near the ground or of a placenta confined to the base of an ovary.

..... RANUNCULACEAE (Myosurus)

31' Perennial herb, or if annual, some leaves cauline

32. Plant submersed; seawater or brackish water of bays and estuaries ..... ZOSTERACEAE (2) {G6,8,13}

32' Plant emergent; fresh or brackish water of coastal or inland areas

33. Nodes swollen; stem generally hollow ..... POACEAE (2) {G5,6,8,13}

33' Nodes not swollen; stem generally filled to center with spongy tissue

34. Leaf generally > 5 mm wide; remnants of old inflorescence a dense 

spike 

1. In flowering plants excluding Asteraceae, Cyperaceae, Poaceae, and some other groups, an unbranched inflorescence in which the flowers are sessile and nearly always open from the bottom to the top of the inflorescence. 2. In Asteraceae, Cyperaceae, Poaceae, and some other groups, a spike-like inflorescence is one in which the inflorescence units (e.g., heads in Asteraceae; spikelets in Cyperaceae and Poaceae), instead of individual flowers, are sessile and attached directly to the main axis of the inflorescence, not to branches, and in which floral development may or may not proceed as in 1.

; inner surface of 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 sheaths mucilaginous ..... TYPHACEAE (Typha)

34' Leaf <= 5 mm wide; remnants of old inflorescence not evident or a 

raceme 

In flowering plants excluding Asteraceae, Cyperaceae, Poaceae, and some other groups, an unbranched inflorescence in which the flowers are borne on pedicels and nearly always open from the bottom to the top of the inflorescence. 2. In Asteraceae, Cyperaceae, Poaceae, and some other groups, a raceme-like inflorescence is one in which the inflorescence units (e.g., heads in Asteraceae; spikelets in Cyperaceae and Poaceae), instead of individual flowers, are stalked and attached directly to the main axis of the inflorescence, not to branches, and in which floral development may or may not proceed as in 1.

; inner surface of sheaths not mucilaginous

35. Leaves ± circular to semicircular in ×-section ..... JUNCAGINACEAE (3) {G10,13,16}

35' Leaves flat ..... PONTEDERIACEAE (Heteranthera limosa)

(3)

25' Leaves 

cylindric 

Elongate, with parallel sides and, at any point, round in transverse section.

or angled

36. Rhizomes and stolons 0; leaves densely tufted

37. Leaf divided lengthwise into 4 hollow chambers; a 

sporangium 

In non-seed plants, a case or sac in which spores are produced, and from which they are released.

generally embedded in adaxial base of each 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

, containing either powdery or larger spores ..... ISOETACEAE {G3}

37' Leaf solid or hollow, but not regularly divided into 4 chambers; a 

sporangium 

In non-seed plants, a case or sac in which spores are produced, and from which they are released.

never embedded in 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

base

38. Plant 

perennial 

Completing life cycle (germination through death) in more than two years or growing seasons, generally non-woody (at least above ground) to woody; includes perennial herbs as well as subshrubs to trees; the abbreviation 'per' only refers to perennial herb, not to the word 'perennial' alone.

 herb; 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

often with internal cross-partitions ..... JUNCACEAE (Juncus) (4)

38' Plant annual; 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

without internal cross-partitions or partitions obscure

39. Leaf bases not sheathing ..... BRASSICACEAE (Subularia)

39' Leaf bases sheathing ..... JUNCAGINACEAE (3) {G10,13,16}

36' Rhizomes or stolons present; leaves tufted or borne along 

rhizome 

1. In seed plants, stem that is often elongate, more or less horizontal, usually underground; distinguished from roots by bearing of leaves, leaf scars, axillary buds, etc. 2. In ferns, stem that is located underground, embedded in leaf litter, on rocks or in rock crevices, or on trees or tree branches, often scaly or hairy; distinguished from roots by bearing of fronds (roots rarely bear fronds), and their greater diameter.

or 

stolon 

A normally thin, elongate stem lying more or less flat on the ground and forming roots as well as erect stems or shoots (which become new, clonal plants) at generally widely spaced nodes; runner.

40. Leaf sharply angled

41. Stem triangular; leaves 3-ranked ..... CYPERACEAE (4) {G8,13}

41' Stem ± round; leaves 2-ranked ..... TYPHACEAE (Sparganium) (3) {G6,8,13}

40' Leaf 

cylindric 

Elongate, with parallel sides and, at any point, round in transverse section.

42. Leaf with internal cross-partitions

43. Leaf soft, blunt, generally <= 15 cm, loosely sheathing; cross-partitions often externally prominent ..... APIACEAE (Lilaeopsis)

43' Leaf generally stiff, 

acute 

Having a short-tapered, sharp tip, the sides convex or straight and converging at less than a right angle.

, often > 15 cm, tightly sheathing; cross-partitions readily apparent by feel but often externally obscure ..... JUNCACEAE (Juncus) (4)

42' Leaf without internal cross-partitions

44. Leaf generally >> 6 cm

45. Stem ± straight; 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 

blade 

Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped.

tip without evident terminal pore; 

ligule 

1. In Asteraceae, the 5-lobed, strap- or fan-shaped outer portion of the corolla of a ligulate flower. 2. In most Poaceae and some other grass-like plants, an appendage at the adaxial junction of leaf sheath and blade, generally membranous, sometimes formed of hairs. 3. In Isoetes and, more obscurely, in Selaginella, a membrane that wholly or partially covers a sporangium.

0.5–5 mm ..... JUNCAGINACEAE (3) {G10,13,16}

45' Stem zigzag; 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 

blade 

Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped.

tip with evident terminal pore; 

ligule 

1. In Asteraceae, the 5-lobed, strap- or fan-shaped outer portion of the corolla of a ligulate flower. 2. In most Poaceae and some other grass-like plants, an appendage at the adaxial junction of leaf sheath and blade, generally membranous, sometimes formed of hairs. 3. In Isoetes and, more obscurely, in Selaginella, a membrane that wholly or partially covers a sporangium.

2–12 mm ..... SCHEUCHZERIACEAE {G10}

44' Leaf 1–7(11) cm

46. Plant 

spreading 

Oriented more or less perpendicularly to the axis of attachment; often, more or less horizontal.

by rhizomes, producing ± spheric, ball-like structures [sporangium cases] ± 2–3 mm diam at bases of some leaves; new leaves uncoiling at tips ..... MARSILEACEAE (Pilularia) {G3}

46' Plant 

spreading 

Oriented more or less perpendicularly to the axis of attachment; often, more or less horizontal.

by stolons, not producing ball-like structures at bases of leaves; new leaves not uncoiling at tips ..... SCROPHULARIACEAE (Limosella) (2) {G18,19}

16' Leaves generally all cauline; stems emergent or taking the form of underwater or floating rhizomes or stolons that are unable to support the plant body outside of water

47. Leaves (or leaf-like branches) compound or very deeply divided

48. Leaf palmately compound — leaflets 4, floating or emergent ..... MARSILEACEAE (Marsilea) (2) {G3}

48' Leaf pinnately compound or variously dissected

49. Leaflets 

lanceolate 

Narrowly elongate, widest in the basal half, often tapered to an acute tip.

or wider; leaves mostly aerial

50. Leaf bases sheathing; 

lobes 

1. A major expansion or bulge, such as on the margin of a leaf, sepal, or petal, or on the surface of an ovary. 2. The free tips of otherwise fused structures, such as sepals or petals; larger than teeth.

or leaflets 

serrate 

Having margins with sharp, fine to coarse teeth generally pointing tipward, not outward; margins with such teeth on such primary teeth are doubly serrate.

to sharply dissected ..... APIACEAE (2) {G6,8,14,20,21}

50' Leaf bases not sheathing; 

lobes 

1. A major expansion or bulge, such as on the margin of a leaf, sepal, or petal, or on the surface of an ovary. 2. The free tips of otherwise fused structures, such as sepals or petals; larger than teeth.

or leaflets 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

or 

dentate 

Having margins with sharp, relatively coarse teeth pointing outward, not tipward.

with ± rounded teeth ..... BRASSICACEAE (Nasturtium, Rorippa)

49' Leaflets or 

lobes 

1. A major expansion or bulge, such as on the margin of a leaf, sepal, or petal, or on the surface of an ovary. 2. The free tips of otherwise fused structures, such as sepals or petals; larger than teeth.

 

linear 

Elongate, with nearly parallel sides; narrower than elliptic or oblong.

, at least on submersed leaves; all or many leaves submersed

51. Underwater parts bearing small, hollow bladders that suck in and trap small organisms when hairs at opening are triggered; plant carnivorous — highly dissected underwater parts are actually modified stems and the bladders are the leaves ..... LENTIBULARIACEAE (Utricularia) {G18}

51' Underwater parts lacking bladder-like traps; plant not carnivorous

52. Submersed leaves 

alternate 

1. Arranged singly, often spirally, along an axis - e.g., one leaf per node. 2. Occurring in different ranks, appearing to be between, not directly above or below, as 'stamens alternate petals'.

..... RANUNCULACEAE (Ranunculus) (3)

52' Submersed leaves 

opposite 

1. Arranged in pairs along an axis - e.g., two leaves per node. 2. Occurring in the same rank, directly above or below, as 'stamens opposite petals'. 3. Located directly across from.

or 

whorled 

Arranged in groups of three or more at nodes or positions along an axis (e.g., three leaves per node).

53. Submersed leaves pinnately divided, central 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 axis evident ..... HALORAGACEAE {G6,8,14,20}

53' Submersed leaves palmately dissected or repeatedly 

forked 

Pertaining to a hair or other structure that branches into two parts.

, central 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 axis 0

54. Submersed leaves palmately dissected; floating leaves 0–few, linear-elliptic, ± 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

..... CABOMBACEAE (Cabomba)

54' Submersed leaves repeatedly 

forked 

Pertaining to a hair or other structure that branches into two parts.

; floating leaves 0 ..... CERATOPHYLLACEAE {G6,8,14,15}

47' Leaves 

simple 

Composed of a single part; undivided; unbranched.

, the margins 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

, toothed, or shallowly lobed

55. Leaves long, narrow, strap-shaped or ribbon-like, often >> 20 cm, generally at least some 

basal 

At or near the base of a plant or plant part. Especially said of leaves clustered near the ground or of a placenta confined to the base of an ovary.

56. Plant of freshwater habitat ..... TYPHACEAE (Sparganium) (3) {G6,8,13}

56' Plant of seawater or brackish water of bays and estuaries ..... ZOSTERACEAE (2) {G6,8,13}

55' Leaves 

linear 

Elongate, with nearly parallel sides; narrower than elliptic or oblong.

to round, generally < 20 cm, generally all cauline

57. Leaf with stipules or sheathing base

58. Principal veins of 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 

pinnate 

Feather-like; pertaining to veins, lobes, leaflets, or other structures arranged in two dimensions (i.e., in one plane) along either side of an axis; a leaf is odd-pinnate if there is a terminal leaflet, even-pinnate if there is not, and either odd- or even-pinnate may be 1-pinnate (blade divided into primary leaflets), 2-pinnate (primary leaflets divided into secondary leaflets), 3-pinnate (secondary leaflets divided into tertiary leaflets), etc.

59. Leaves 

opposite 

1. Arranged in pairs along an axis - e.g., two leaves per node. 2. Occurring in the same rank, directly above or below, as 'stamens opposite petals'. 3. Located directly across from.

or 

whorled 

Arranged in groups of three or more at nodes or positions along an axis (e.g., three leaves per node).

, 2–15 mm ..... ELATINACEAE

59' Leaves 

alternate 

1. Arranged singly, often spirally, along an axis - e.g., one leaf per node. 2. Occurring in different ranks, appearing to be between, not directly above or below, as 'stamens alternate petals'.

, >> 15 mm ..... POLYGONACEAE {G6,8,15,16,19}

58' Principal veins of 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

parallel or pinnate-parallel or only 1 leaf vein apparent

60. Leaves generally ± 

opposite 

1. Arranged in pairs along an axis - e.g., two leaves per node. 2. Occurring in the same rank, directly above or below, as 'stamens opposite petals'. 3. Located directly across from.

or appearing 

whorled 

Arranged in groups of three or more at nodes or positions along an axis (e.g., three leaves per node).

61. Leaves emergent or floating; 

nodes 

Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise.

swollen, 

internodes 

Segment of an axis (generally a stem) between successive positions (nodes) from which one or more structures (especially leaves, buds, branches, or flowers) arise.

generally hollow ..... POACEAE (2) {G5,6,8,13}

61' Leaves submersed or some floating; 

nodes 

Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise.

generally not swollen, 

internodes 

Segment of an axis (generally a stem) between successive positions (nodes) from which one or more structures (especially leaves, buds, branches, or flowers) arise.

generally solid

62. Leaves minutely toothed (teeth sometimes appearing ± 0 to naked eye); 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

base abruptly expanded, forming 

sheath 

A surrounding or partially surrounding, often tubular structure or part of a structure, such as a leaf base in Apiaceae or Poaceae.

, stipules 0 ..... HYDROCHARITACEAE (Najas) {G8,13}

62' Leaves 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

; 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

base not abruptly expanded, stipules present, free or fused to leaf base forming a 

sheath 

A surrounding or partially surrounding, often tubular structure or part of a structure, such as a leaf base in Apiaceae or Poaceae.

..... ZANNICHELLIACEAE {G8,10,13}

60' Leaves generally 

alternate 

1. Arranged singly, often spirally, along an axis - e.g., one leaf per node. 2. Occurring in different ranks, appearing to be between, not directly above or below, as 'stamens alternate petals'.

63. Stipules ± completely fused to 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 

blade 

Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped.

base ..... RUPPIACEAE {G8,10,13}

63' Stipules fused to 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 

blade 

Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped.

base <= 2/3 their length

64. Roots branched; leaves 

linear 

Elongate, with nearly parallel sides; narrower than elliptic or oblong.

; midvein of 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

not differentiated from other veins; floating leaves 0 ..... PONTEDERIACEAE (Heteranthera dubia)

64' Roots generally unbranched; leaves 

linear 

Elongate, with nearly parallel sides; narrower than elliptic or oblong.

to 

ovate 

Egg-shaped (i.e., widest below the middle) in two dimensions (i.e., in one plane), as a leaf.

; midvein of 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

more prominent than other veins; floating leaves often present ..... POTAMOGETONACEAE {G10,13}

57' Leaf without stipules or sheathing base

65. Leaves 

alternate 

1. Arranged singly, often spirally, along an axis - e.g., one leaf per node. 2. Occurring in different ranks, appearing to be between, not directly above or below, as 'stamens alternate petals'.

66. Leaves 

sessile 

Without a petiole, peduncle, pedicel, or other kind of stalk.

; annual ..... CAMPANULACEAE {G5,14,17}

66' Leaves petioled; perennial herb

67. Leaves toothed or lobed ..... RANUNCULACEAE (Ranunculus) (3)

67' Leaves 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

68. Lateral 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 veins strongly diverging from midvein ..... ONAGRACEAE (Ludwigia) (2)

68' Lateral 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 veins strongly 

ascending 

Curving or angling upward from base, or about 30–60 degrees less than vertical or away from axis of attachment.

to nearly parallel to midvein ..... RANUNCULACEAE (Ranunculus) (3)

65' Leaves 

opposite 

1. Arranged in pairs along an axis - e.g., two leaves per node. 2. Occurring in the same rank, directly above or below, as 'stamens opposite petals'. 3. Located directly across from.

or 

whorled 

Arranged in groups of three or more at nodes or positions along an axis (e.g., three leaves per node).

69. Leaves 

whorled 

Arranged in groups of three or more at nodes or positions along an axis (e.g., three leaves per node).

70. Leaf minutely toothed (teeth sometimes appearing ± 0 to naked eye) ..... HYDROCHARITACEAE (2) {G6,8,16}

70' Leaf 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

..... PLANTAGINACEAE (Hippuris) {G14,15}

69' Leaves 

opposite 

1. Arranged in pairs along an axis - e.g., two leaves per node. 2. Occurring in the same rank, directly above or below, as 'stamens opposite petals'. 3. Located directly across from.

71. Leaves fleshy

72. Leaves 2–6 mm, 

linear 

Elongate, with nearly parallel sides; narrower than elliptic or oblong.

or oblanceolate; annual; plant generally ± red ..... CRASSULACEAE (Crassula aquatica)

72' Leaves 3–50 mm 

linear 

Elongate, with nearly parallel sides; narrower than elliptic or oblong.

to obovate; annual or 

perennial 

Completing life cycle (germination through death) in more than two years or growing seasons, generally non-woody (at least above ground) to woody; includes perennial herbs as well as subshrubs to trees; the abbreviation 'per' only refers to perennial herb, not to the word 'perennial' alone.

 herb; plant generally not red ..... MONTIACEAE (Montia) {G5}

71' Leaves not or scarcely fleshy

73. Leaves 0.5–5 mm wide

74. Leaves aerial ..... LINDERNIACEAE {G5,18}

74' Leaves submersed or floating

75. Leaves minutely toothed (teeth sometimes appearing ± 0 to naked eye) to coarsely 

dentate 

Having margins with sharp, relatively coarse teeth pointing outward, not tipward.

, generally enlarged at base, all similar in form and submersed ..... HYDROCHARITACEAE (2) {G6,8,16}

75' Leaves 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

, 

linear 

Elongate, with nearly parallel sides; narrower than elliptic or oblong.

to 

ovate 

Egg-shaped (i.e., widest below the middle) in two dimensions (i.e., in one plane), as a leaf.

, not enlarged at base, sometimes with floating distal leaves different from submersed leaves ..... PLANTAGINACEAE (Callitriche) {G8,15}

73' Leaves 6–15+ mm wide

76. Leaf veins 

palmate 

More than two structures or parts (e.g., veins, lobes, or leaflets) radiating from a common point in two dimensions (i.e., in one plane).

..... LINDERNIACEAE

, PHRYMACEAE, or PLANTAGINACEAE

76' Leaf veins 

pinnate 

Feather-like; pertaining to veins, lobes, leaflets, or other structures arranged in two dimensions (i.e., in one plane) along either side of an axis; a leaf is odd-pinnate if there is a terminal leaflet, even-pinnate if there is not, and either odd- or even-pinnate may be 1-pinnate (blade divided into primary leaflets), 2-pinnate (primary leaflets divided into secondary leaflets), 3-pinnate (secondary leaflets divided into tertiary leaflets), etc.

77. Leaves toothed ..... LINDERNIACEAE

, PHRYMACEAE, or PLANTAGINACEAE

77' Leaves 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

78. Leaves (3)5–13 cm; stems often swollen, hollow ..... AMARANTHACEAE (Alternanthera)

78' Leaves < 5 cm; stems not swollen ..... ONAGRACEAE ( Ludwigia) or PLANTAGINACEAE (Veronica) (2)