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Key to families | Table of families and genera
This text currently parallels The Jepson Manual: Vascular Plants of California, Second Edition that is now available at the University of California Press.
Text appearing in blue on this page will not appear in the printed book; it will be displayed only on the Web. Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.
Annual, perennial herb, rhizomed or not, tubers 0, winter buds generally 0.
Stem: simple or branched, cylindric to compressed; nodal glands present or 0.
Leaf: submersed, also floating or not, generally flat, generally green, entire to finely serrate; submersed sessile or not, linear to round, tip rounded to acuminate, veins 1–35; floating 0 or generally petioled, elliptic to ovate, leathery; stipules of submersed leaves free from blade base or fused to it < 1/2 stipule length.
Inflorescence: generally floating to emergent; peduncle stiff.
Fruit: generally beaked, abaxially with 0 or 1 central keel, 0 or 2 lateral, sometimes lower keels, sides concave to convex.
± 88 species: generally temperate n hemisphere. (Greek: river neighbor, from aquatic habitat) Other taxa in TJM (1993) moved to Stuckenia.
Unabridged references: [Haynes 1974 Rhodora 76:564–649; Haynes 1985 Sida 11:173–188; Wiegleb 1988 Fedde Rep Sp Nov Regni Veg 99:249–266; Wiegleb & Kaplan 1998, Folia Geobot 33: 241–316.]
1. Lvs submersed and floating
2. Submersed leaves linear, < 1 cm wide
3. Stipules fused to blade base; inflorescences of 2 kinds, lower submersed, spheric, upper emergent, cylindric; fruit compressed ..... P. diversifolius (2)
3' Stipules free from blade base; inflorescences all emergent, ± cylindric; fruit ± compressed or not
4. Submersed leaves with a net-like band along midrib, ribbon-like, 2–10 mm wide ..... P. epihydrus (2)
4' Submersed leaves without a net-like band along midrib, not ribbon-like, either cylindric, often petiole-like, < 2 mm wide, or linear to lance-elliptic, 10–40 mm wide ..... P. natans
2' Submersed leaves linear or wider, generally 1–7 cm wide
5. Submersed leaves curved backward, generally folded along midvein, generally lanceolate to ovate; floating leaves 27–50-veined ..... P. amplifolius (2)
5' Submersed leaves not curved backward, not folded along midvein, lanceolate to elliptic to oblanceolate; floating leaves < 30-veined
6. Submersed leaves petioled
7. Submersed leaves microscopically serrate near tip, petioles 0.5–4 cm ..... P. illinoensis (4)
7' Submersed leaves entire, petioles 2–13 cm ..... P. nodosus (2)
6' Submersed leaves sessile (petioles rarely <= 3 cm in P. gramineus)
8. Submersed leaves 3–9-veined; fruit 1.9–2.3 mm ..... P. gramineus (2)
8' Submersed leaves 7–19-veined; fruit 2.5–3.6 mm
9. Floating leaves 7–15-veined; submersed leaves 7–9-veined, entire ..... P. alpinus (2)
9' Floating leaves 13–29-veined; submersed leaves 7–19-veined, microscopically serrate near tip ..... P. illinoensis (4)
1' Lvs submersed
10. Lvs linear or ovate to lanceolate to elliptic to oblanceolate, sessile or petioled
11. Lf blade serrate; fruit beak 2–3 mm ..... P. crispus
11' Lf blade entire or microscopically serrate near tip; fruit beak < 2 mm
12. Lf base not clasping
13. Petioles 0.5–26 cm
14. Lf microscopically serrate near tip, tip acute-mucronate ..... P. illinoensis (4)
14' Lf entire, tip acute
15. Lvs 19–50-veined, curved backward, generally folded along midvein ..... P. amplifolius (2)
15' Lvs 7–15-veined, not curved backward, not folded along midvein ..... P. nodosus (2)
13' Petioles 0
16. Lvs entire, 7–9-veined; fruit pedicelled ..... P. alpinus (2)
16' Lvs minutely to microscopically serrate near tip, 3–19-veined; fruit sessile
17. Lf blade 3–9-veined, 2–10 cm, (3)10–27 mm wide; fruit 1.9–2.3 mm, beak erect, 0.3–0.5 mm ..... P. gramineus (2)
17' Lf blade 7–19-veined, 6–20 cm, 15–50 mm wide; fruit 2.5–3.6 mm, beak erect to ± recurved, 0.5–0.8 mm ..... P. illinoensis (4)
12' Lf base clasping
18. Lf lance-linear, 5–20 cm, tip hood-like, splitting when dry; stipules 2–10 cm, persistent; stems often zigzag; fruit 4–5 mm, keels 1(3) ..... P. praelongus
18' Lf linear- to lance-ovate, 1–12 cm, tip flat, not hood-like, not splitting when dry; stipules < 2 cm, persistent as fibers; stems generally straight; fruit 2–4 mm, keels 0(1) ..... P. richardsonii
10' Lvs linear (linear to lanceolate in P. robbinsii), sessile
19. Stipules fused to blade base for ± 1/4 to 1/2 stipule length, or 1–15 mm, sheath-like basally, liguled.
20. Lvs thin, not conspicuously 2-ranked, vein 1, not fine ..... P. diversifolius (2)
20' Lvs ± stiff, 2-ranked, 3–4(8) mm wide, veins 20–60, fine ..... P. robbinsii
19' Stipules free from or fused to blade base for <= 1/5 stipule length, or 1–2 mm, not sheath-like basally, not liguled
21. Lf veins 15–35; stems compressed, winged ..... P. zosteriformis
21' Lf veins 1–13; stems ± compressed or cylindric
22. Rhizomes present, winter buds 0; fruit 2.5–4.5 mm, 2–3.6 mm wide; stems compressed ..... P. epihydrus (2)
22' Rhizomes 0, winter buds present; fruit 1.4–2.7 mm, 1.1–2.2 mm wide; stems rounded to ± compressed
23. Fr with wing-like keel; peduncles 0.3–1.1(3.7) cm; nodal glands 0 (faint)..... P. foliosus
24. Stipule veins in age persisting as fibers; inflorescence interrupted; fruit pale green, 1.4–1.7 mm, 1.1–1.2 mm wide, keel < 0.2 mm high, beak <= 0.2 mm ..... subsp. fibrillosus
24' Stipule veins in age decaying, occasionally persistent as delicate fibers; inflorescence generally not interrupted; fruit olive to green-brown, 1.5–2.7 mm, 1.2–2.2 mm wide, keel 0.2–0.4 mm high, beak 0.2–0.6 mm ..... subsp. foliosus
23' Fr without keel; peduncles 0.5–8 cm; nodal glands present
25. Fr widest at or below middle, sides convex (concave); peduncles per plant > 3; inflorescence continuous; stipules free ..... P. berchtoldii
25' Fr widest above middle, sides concave; peduncles per plant 1–3; inflorescence interrupted; stipules fused below middle ..... P. pusillus
Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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