Podostemum ceratophyllum |
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horn-leaf riverweed, podostémon à feuilles cornées, threadfoot |
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Roots | flattened or elliptic, 0.3–1.1 mm diam. |
Stems | 1.8–9 mm apart, 0.4–300 × 0.5–1.5 mm at base. |
Leaves | stipules caducous (absent from leaves 3–9 nodes back from stem apex), 0.5–3.6 mm, margins entire; petiole arising perpendicular to stem axis or upright, 0.4–59 mm; blade 1–13 times dichotomously divided, 1.7–142 mm, ultimate divisions flattened, spatulate, linear, or awl-shaped, 0.2–40 × 0.05–0.8 mm, central vein faint or absent. |
Inflorescences | spathella 1.5–6.2 × 0.8–1.8 mm. |
Pedicels | 0.4–2.9 mm, to 0.6–10.5 mm in anthesis, 0.5–9 mm in fruit. |
Flowers | tepals linear or awl-shaped, apex acute, lateral tepals 0.7–2 mm, andropodial tepals 0.1–1.1 mm; andropodium 0.1–3.3 mm, 0.7–4.3 mm in anthesis; filaments 0.2–0.9 mm, 0.3–2 mm in anthesis; anthers 0.5–1.5 × 0.4–0.8 mm; ovary 0.7–2.6 × 0.4–1.4 mm; stigmas 0.3–1.4 mm, 0.4–1.5 mm in anthesis. |
Capsules | 1.4–3.1 × 0.7–1.7 mm. |
Seeds | 0.4–0.8 × 0.5–0.8 mm. |
Podostemum ceratophyllum |
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Phenology | Flowering Jun–Sep. |
Habitat | Attached to rocks and other solid substrata in swift currents |
Elevation | 0–800 m (0–2600 ft) |
Distribution |
AL; AR; CT; GA; KY; LA; MA; MD; ME; MS; NC; NH; NJ; NY; OH; OK; PA; RI; SC; TN; VA; VT; WV; NB; NS; ON; PE; QC; West Indies (Dominican Republic); Central America (Honduras)
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Discussion | Podostemum ceratophyllum is listed as rare, endangered, or of special concern in some regions. Paucity of appropriate habitat and human disturbances (for example, siltation, damming) have contributed to conservation concerns. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 6, p. 70. |
Parent taxa | Podostemaceae > Podostemum |
Synonyms | Lacis ceratophylla, P. abrotanoides, P. ceratophyllum var. abrotanoides, P. ceratophyllum var. circumvallatum, P. ceratophyllum var. fluitans |
Name authority | Michaux: Fl. Bor.-Amer. 2: 165, plate 44. (1803) |
Web links |