Flora of North America species comparison

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Hippuris

Plantaginaceae

mare's-tail

plantain family
Habit Herbs, perennial; rhizomatous, emergent aquatics in fresh or brackish water. Herbs, subshrubs, or shrubs, annual or perennial, sometimes biennial, rarely fleshy (Plantago maritima), autotrophic.
Stems

erect, glabrous.

prostrate, decumbent, ascending, or erect, sometimes arching, creeping, sprawling, spreading, scrambling, pendent, climbing, or reclining, sometimes absent.
Leaves

cauline, whorled;

petiole absent;

blade not fleshy, not leathery (fleshy or leathery in H. tetraphylla), margins entire.

deciduous or persistent, basal, basal and cauline, or cauline, opposite, subopposite, alternate, helical, or whorled, sometimes opposite proximally, alternate distally, simple;

stipules absent;

petiole present or absent;

blade fleshy or not, leathery or not, margins entire to subentire, toothed, or lobed.
Inflorescences

axillary, flowers solitary;

bracts absent.

axillary or terminal, spikes, racemes, cymes, corymbs, thyrses, whorls, panicles, spiciform, or flowers 1–4.
Pedicels

present (proximal) or absent (distal);

bracteoles absent.

Flowers

bisexual or unisexual;

calyx a minute rim adhering to summit of inferior ovary;

petals 0;

stamen 1, adnate to ovary, filaments glabrous;

staminode 0;

ovary 1-locular, placentation apical;

stigma linear along surfaces of style.

bisexual, rarely unisexual (Callitriche, Hippuris, Littorella), perianth and androecium hypogynous (epigynous in Hippuris);

sepals (2–)4 or 5, basally or proximally connate, sometimes distinct, rarely a minute rim (Hippuris) or 0 (Callitriche), calyx radially or bilaterally symmetric;

petals 0 (Callitriche, Hippuris) or (3 or)4 or 5, connate, corolla radially or bilaterally symmetric, ± bilabiate, bilabiate and personate, or regular, rarely unilabiate (Synthyris), ± rotate to salverform, ± cylindric, tubular, funnelform, urceolate, ellipsoid, globular, ovoid, or ligulate;

stamens (1 or)2–4 or 5, adnate to corolla or free, didynamous or equal, staminodes 0 or 1(–3);

pistil 1, 2-carpellate (1 in Hippuris), ovary superior (inferior in Hippuris), 2-locular, sometimes 1-locular or 4-locular (Callitriche), placentation axile, sometimes parietal (Dopatrium), parietal centrally and axile distally and proximally (Synthyris), apical (Hippuris), basal (Callitriche, Littorella), or free-central (Plantago);

ovules anatropous, hemitropous, hemianatropous, or campylotropous, unitegmic, tenuinucellate;

styles [0]1 (2 in Callitriche);

stigma 1 (2 in Callitriche).
Fruits

drupes.

capsules, dehiscence loculicidal, septicidal, or poricidal, or nutlets (Littorella), pyxides (Plantago), schizocarps (Callitriche), drupes (Hippuris), or drupelike (Lagotis).
Seeds

1, brownish, globular, wings absent.

1–300, white, tan, brown, yellow, gray, black, maroon, or red, ovoid to ellipsoid, cylindric, globular, oblong, conic, disciform, patelliform, or angled;

embryo straight, rarely curved, endosperm present.
x

= 8.

Hippuris

Plantaginaceae
Distribution
from USDA
North America; South America; Eurasia [Introduced in Australia]
[BONAP county map]
nearly worldwide; apparently absent in much of tropical South America; and arid northern Africa and northern Australia
[BONAP county map]
Discussion

Species 4 (4 in the flora).

Leaf characteristics of Hippuris used here are derived from whorls on the emergent portions of the stems; morphology of submerged leaves differs sharply from that of emergent shoots.

M. E. McCully and H. M. Dale (1961) proposed that the taxa treated below all could be expressions of phenotypic plasticity of Hippuris vulgaris developed in different regimes of salts and photoperiod; this was not accepted by E. Hultén (1973), nor is it accepted here. Number of leaves in a whorl varies among plants and even on the same stem. Nevertheless, there are clear limits and discontinuities in leaf number and shape among taxa, which are well-correlated with less variable characters as well as with ecology and geography.

Hippuris has been placed in Halagoraceae or in Hippuridaceae as a monogeneric family. Molecular phylogenetic studies now place it in Plantaginaceae (D. C. Albach et al. 2005).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Genera ca. 100, species ca. 1900 (45 genera, 460 species in the flora).

The concept of Plantaginaceae has expanded considerably since the molecular study by R. G. Olmstead and P. A. Reeves (1995) reported that many of the genera at that time placed in the Scrophulariaceae did not cluster with Scrophularia and instead formed a clade with genera that usually had been considered to be distantly related and placed in different families, including Callitriche, Hippuris, and Plantago. As treated here, Plantaginaceae include Callitrichaceae Link and Hippuridaceae Vest. Subsequent studies (for example, D. C. Albach et al. 2005; B. Oxelman et al. 2005) have confirmed this basic alignment; as yet, there is no comprehensive phylogenetic classification of the family. Albach et al. suggested that the genera of Plantaginaceae might be placed in 12 tribes, noting molecular support for at least six of them. Species in the flora area are distributed among nine of the 12 tribes: Angelonieae Pennell (genus 1), Antirrhineae Dumortier (genera 2–18), Callitricheae Dumortier (genera 19 and 20), Cheloneae D. Don (genera 21–27), Digitalideae Dumortier (genus 28), Gratioleae D. Don (genera 29–38), Plantagineae Dumortier (genera 39 and 40), Russelieae Pennell (genus 41), and Veroniceae Duby (genera 42–45). Angelonieae, Digitalideae, and Russelieae are represented in the flora area only by introduced species. Within the family, genera are arranged alphabetically within tribes.

In the flora area, 20 of the 45 genera contain one species each; Penstemon contains nearly half of all North American Plantaginaceae species. Chelone, Chionophila, Holmgrenanthe, Howelliella, Nothochelone, Sophronanthe, and Tonella are endemic. Genera that include popular ornamental plants are Angelonia, Antirrhinum, Bacopa, Chelone, Digitalis, Linaria, Penstemon, Russelia, Veronica, and Veronicastrum. Ten genera are represented only by introduced species: Angelonia, Antirrhinum, Chaenorhinum, Cymbalaria, Digitalis, Kickxia, Limnophila, Linaria, Misopates, and Russelia. Linaria, Plantago, Scoparia, and Veronica contain globally important pest species, some of which are listed as noxious weeds in parts of the flora area.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Flowers unisexual; leaves 2–10 mm, midveins often conspicuous, lateral veins absent; stems 15–100 mm; rhizomes 1 mm diam.
H. montana
1. Flowers bisexual; leaves 3–35 mm, midveins inconspicuous, lateral veins present, sometimes obscure; stems 80–500 mm; rhizomes (2–)3–7 mm diam.
→ 2
2. Leaves on mid portions of emergent shoots in whorls of (7 or)8 or 9(–12), tips often curled in dried plants; filaments longer than anthers.
H. vulgaris
2. Leaves on mid portions of emergent shoots in whorls of 3–6(or 7), tips not curled in dried plants; filaments equal to or shorter than anthers.
→ 3
3. Leaves on mid portions of emergent shoots in whorls of (5 or)6(or 7), linear to narrowly oblong or lanceolate, 0.5–1.5 mm wide, apices subacute.
H. lanceolata
3. Leaves on mid portions of emergent shoots in whorls of 3–5(or 6), oblanceolate or oblong to broadly obovate, 2–8 mm wide, apices obtuse, rounded, or blunt.
H. tetraphylla
1. Corolla lobes 0; stamens 1; sepals 0 or minute rims at summits of ovaries.
→ 2
2. Leaves opposite; fruits schizocarps; ovaries superior; styles 2.
Callitriche
2. Leaves whorled; fruits drupes; ovaries inferior; styles 1.
Hippuris
1. Corolla lobes 3–5, rarely 0; stamens 2–4(or 5); sepals 2–5.
→ 3
3. Corolla tubes spurred, ± saccate, or gibbous, or with rounded sacs at bases of median lobes.
→ 4
4. Corolla tubes with rounded sacs at bases of median lobes.
Angelonia
4. Corolla tube bases spurred, ± saccate, or gibbous, sometimes obscurely so.
→ 5
5. Corolla tube bases ± saccate or gibbous adaxially, sometimes obscurely so.
→ 6
6. Corollas: middle lobes of abaxial lips folded lengthwise, enclosing stamens and styles; stamens included.
Collinsia
6. Corollas: middle lobes of abaxial lips not folded lengthwise, not enclosing stamens and styles; stamens exserted.
Tonella
5. Corolla tube bases spurred or gibbous abaxially.
→ 7
7. Corolla tube bases spurred.
→ 8
8. Inflorescences terminal, racemes.
→ 9
9. Corolla abaxial lips as long as or slightly longer than adaxials; filaments usually hairy proximally; capsules 9–12 mm.
Linaria
9. Corolla abaxial lips much longer than adaxials; filaments glabrous; capsules 2–4.8 mm.
Nuttallanthus
8. Inflorescences axillary or terminal, flowers solitary.
→ 10
10. Stems ascending or erect; leaf blades linear, lanceolate, or oblanceolate; calyx lobes glandular-pubescent.
→ 11
11. Pedicels 5–20 mm.
Chaenorhinum
11. Pedicels 1–4 mm.
Sairocarpus
10. Stems pendent, decumbent, prostrate, or erect; leaf blades oblong-ovate, orbiculate, cordate, or reniform; calyx lobes glabrous or villous.
→ 12
12. Perennials; stems glabrous; calyx lobes glabrous.
Cymbalaria
12. Annuals; stems villous to glandular-hairy; calyx lobes villous.
Kickxia
7. Corolla tube bases gibbous.
→ 13
13. Inflorescences terminal, racemes.
→ 14
14. Corollas strongly bilabiate, not personate.
Howelliella
14. Corollas bilabiate and personate.
→ 15
15. Corollas 25–45 mm; capsules 10–15 mm.
Antirrhinum
15. Corollas 9–18 mm; capsules 4–11 mm.
→ 16
16. Calyx lobes linear, usually longer than corolla tubes in flower; seed wings present.
Misopates
16. Calyx lobes ovate to lanceolate, shorter than or as long as corolla tubes in flower; seed wings absent.
Sairocarpus
13. Inflorescences axillary, flowers solitary.
→ 17
17. Corollas bilabiate; stamens 2; staminodes 2 or 3.
Mohavea
17. Corollas bilabiate and personate; stamens 4; staminodes 0 or 1.
→ 18
18. Locules unequal.
Sairocarpus
18. Locules equal.
→ 19
19. Stems erect, ascending, or sprawling, glabrous or hairy; bracts absent; pedicels twining; pollen sacs 2.
Neogaerrhinum
19. Stems erect, glandular-hairy; bracts present; pedicels not twining, recurved in fruit; pollen sacs 1.
Pseudorontium
3. Corolla tubes not spurred, gibbous, or saccate.
→ 20
20. Shrubs or subshrubs.
→ 21
21. Stamens 2.
Veronica
21. Stamens 4.
→ 22
22. Distal leaf blades needlelike or scalelike; capsules densely packed with white, membranous hairs; inflorescences axillary, cymes.
Russelia
22. Distal leaf blades not needlelike or scalelike; capsules not densely packed with white, membranous hairs; inflorescences terminal, panicles, thyrses, corymbs, racemes, or spikelike racemes.
→ 23
23. Staminodes 0; bracteoles absent; leaves whorled.
Gambelia
23. Staminodes 1; bracteoles usually present; leaves opposite, subopposite, or whorled, distals rarely alternate.
→ 24
24. Stamen filament bases eglandular-hairy; nectaries hypogynous discs.
Keckiella
24. Stamen filament bases glabrous or glandular-puberulent proximally, rarely pubescent distally; nectaries epistaminal.
Penstemon
20. Herbs.
→ 25
25. Fruits pyxides or nutlets; leaves basal only, rarely cauline; corolla lobes 4; stamens free.
→ 26
26. Flowers unisexual; fruits nutlets; leaf blade margins entire.
Littorella
26. Flowers bisexual; fruits pyxides; leaf blade margins entire or toothed.
Plantago
25. Fruits capsules, rarely drupelike; leaves basal and cauline or cauline only, rarely basal only; corolla lobes 0 or 3–5; stamens adnate to corolla, rarely inserted on receptacle.
→ 27
27. Stamens 2 or 3.
→ 28
28. Ovaries 1-locular; leaves basal or basal and cauline.
→ 29
29. Leaf blade margins entire; petioles absent; sepals 5; inflorescences of solitary flowers; annuals.
Dopatrium
29. Leaf blade margins toothed or deeply incised to pinnatifid; petioles present; sepals 2–4(or 5); inflorescences racemes; perennials.
Synthyris
28. Ovaries 2-locular; leaves cauline, sometimes basal and cauline.
→ 30
30. Sepals 2; corolla lobes 3; fruits drupelike.
Lagotis
30. Sepals 4 or 5; corolla lobes 4 or 5; fruits capsules.
→ 31
31. Bracts absent; stems prostrate; corollas radially symmetric, rarely bilaterally symmetric, regular.
Bacopa
31. Bracts present; stems creeping to decumbent, ascending, or erect; corollas bilaterally symmetric, weakly bilabiate, bilabiate, or bilabiate and personate, sometimes regular.
→ 32
32. Corolla lobes 5.
→ 33
33. Leaf blades not leathery; pollen sacs perpendicular to filaments, connectives dilated.
Gratiola
33. Leaf blades leathery; pollen sacs parallel to filaments, connectives not dilated.
Sophronanthe
32. Corolla lobes 4.
→ 34
34. Leaves opposite, distals sometimes alternate; stamen filaments glabrous.
Veronica
34. Leaves whorled, rarely opposite; stamen filaments hairy proximally.
Veronicastrum
27. Stamens 4(or 5).
→ 35
35. Leaves alternate.
→ 36
36. Staminodes 0; inflorescences terminal, racemes; bracts present.
Digitalis
36. Staminodes 1; inflorescences axillary, flowers solitary; bracts absent.
→ 37
37. Leaf blade margins entire; corollas blue to violet, pink, or red.
→ 38
38. Annuals; seed wings present.
Epixiphium
38. Perennials; seed wings absent.
Maurandella
37. Leaf blade margins dentate or spinulose; corollas pale yellow to yellow or ochroleucous.
→ 39
39. Leaf blade margins spinulose; stems erect; ovaries 1-locular.
Holmgrenanthe
39. Leaf blade margins dentate; stems pendent; ovaries 2-locular.
Mabrya
35. Leaves opposite or whorled, distals sometimes alternate.
→ 40
40. Plants paludal or aquatic; leaves dimorphic, margins of submerged leaves pinnatifid, margins of aerial leaves entire, serrate, or pinnatifid.
Limnophila
40. Plants terrestrial or, if paludal or aquatic, leaves monomorphic and margins of leaves rarely pinnatifid.
→ 41
41. Corollas radially symmetric.
→ 42
42. Corolla lobes 5, rarely 4, throats not densely pilose internally; bracteoles present.
Bacopa
42. Corolla lobes 4, throats densely pilose internally; bracteoles absent.
Scoparia
41. Corollas bilaterally symmetric, rarely nearly radially symmetric.
→ 43
43. Seeds 2 or 4; stamens equal; annuals; stigmas linear.
Tonella
43. Seeds (2–)5–150; stamens didynamous, rarely equal; perennials, sometimes annuals; stigmas capitate, 2-lobed, or cuneate.
→ 44
44. Staminodes 1.
→ 45
45. Bracteoles absent; leaf blade margins entire; seed wings present.
Chionophila
45. Bracteoles present; leaf blade margins toothed or entire; seed wings absent or present.
→ 46
46. Bracteoles ± as large as calyx lobes, nearly surrounding calyces of flowers they subtend.
Chelone
46. Bracteoles smaller than calyx lobes, not surrounding calyces of flowers they subtend.
→ 47
47. Inflorescences spikes, racemes, or flowers solitary; calyces bilaterally symmetric; capsule dehiscence loculicidal.
Stemodia
47. Inflorescences cymes or thyrses; calyces radially symmetric or nearly so; capsule dehiscence septicidal.
→ 48
48. Stamen filaments hirsute proximally, puberulent distally; seed wings present; nectaries hypogynous discs.
Nothochelone
48. Stamen filaments glabrous or glandular-puberulent proximally, rarely pubescent distally; seed wings absent, sometimes narrow; nectaries epistaminal.
Penstemon
44. Staminodes 0.
→ 49
49. Leaf blade margins pinnatifid to bipinnatifid; bracteoles absent.
→ 50
50. Corollas pale blue to pale lavender; seeds white, parallel-ridged.
Leucospora
50. Corollas pink or purple; seeds yellow or brown, spirally ridged.
Schistophragma
49. Leaf blade margins entire, crenate, serrate, dentate, or denticulate; bracteoles present.
→ 51
51. Leaf blade margins entire; sepals distinct, outer wider than inner.
Bacopa
51. Leaf blade margins toothed; sepals basally or proximally connate, outer calyx lobes ± as wide as inner.
→ 52
52. Inflorescences spikelike cymes; bracteoles ± as large as calyx lobes, nearly surrounding calyces of flowers they subtend; calyces radially symmetric.
Chelone
52. Inflorescences spikes, racemes, or flowers solitary; bracteoles smaller than calyx lobes, not surrounding calyces of flowers they subtend; calyces bilaterally symmetric.
→ 53
53. Stems glabrous; petioles present.
Mecardonia
53. Stems hairy; petioles absent.
Stemodia
Source FNA vol. 17, p. 55. Authors: Reidar Elven, David F. Murray, Heidi Solstad. FNA vol. 17, p. 11. Authors: Craig C. Freeman, Richard K. Rabeler, Wayne J. Elisens.
Parent taxa Plantaginaceae
Subordinate taxa
H. lanceolata, H. montana, H. tetraphylla, H. vulgaris
Angelonia, Antirrhinum, Bacopa, Callitriche, Chaenorhinum, Chelone, Chionophila, Collinsia, Cymbalaria, Digitalis, Dopatrium, Epixiphium, Gambelia, Gratiola, Hippuris, Holmgrenanthe, Howelliella, Keckiella, Kickxia, Lagotis, Leucospora, Limnophila, Linaria, Littorella, Mabrya, Maurandella, Mecardonia, Misopates, Mohavea, Neogaerrhinum, Nothochelone, Nuttallanthus, Penstemon, Plantago, Pseudorontium, Russelia, Sairocarpus, Schistophragma, Scoparia, Sophronanthe, Stemodia, Synthyris, Tonella, Veronica, Veronicastrum
Name authority Linnaeus: Sp. Pl. 1: 4. (1753): Gen. Pl. ed. 5, 4. (1754) Jussieu
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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