. An illustrated flora of the northern United States, Canada and the British possessions, from Newfoundland to the parallel of the southern boundary of Virginia, and from the Atlantic Ocean westward to the 102d meridian. Botany; Botany. Genus PONDWEED FAMILY. 75 Nearly the same breadth throughout, obtusely pointed, coarsely cellular-reticulated in the middle. 5. P. epihydrus. Broader at base, acute, without cellular-reticulation. 9. P. heterophyllus. Submerged leaves all alike, lanceolate. Uppermost leaves petioled, lowest sessile. 6. p. alpinus. All the leaves petioled. Floating leaves large,
. An illustrated flora of the northern United States, Canada and the British possessions, from Newfoundland to the parallel of the southern boundary of Virginia, and from the Atlantic Ocean westward to the 102d meridian. Botany; Botany. Genus PONDWEED FAMILY. 75 Nearly the same breadth throughout, obtusely pointed, coarsely cellular-reticulated in the middle. 5. P. epihydrus. Broader at base, acute, without cellular-reticulation. 9. P. heterophyllus. Submerged leaves all alike, lanceolate. Uppermost leaves petioled, lowest sessile. 6. p. alpinus. All the leaves petioled. Floating leaves large, broadly elliptic, rounded or subcordate at base. 11. P. illinoensis. Floating leaves narrowly elliptical, tapering at base. 7. P. americanus. Floating leaves mostly obovate or oblanceolate, tapering at base. 8. P. Faxoni. All the leaves sessile or subsessile. Fruit only 1 line long, obscurely 3-keeled. 10. P. varians. Fruit zyi lines long, distinctly 3-keeled. 12. P. With submerged leaves only. Without propagating buds and without glands. Leaves with broad blades, mostly lanceolate or ovate, many-nerved. Leaves subsessile or short-petioled, mostly acute or cuspidate. 13. P. lucens. Leaves semi-amplexicaul, obtuse and cucullate at the apex. 14. P. praelongus. Leaves meeting around the stem, very obtuse at the apex, not cucullate. 15. P. perfoliatus. Leaves with narrow blades, linear or oblong-linear, several-nerved. Leaves oblong-linear, 5-7-nerved, obtuse at the apex. 16. P. mysticus. Leaves narrowly linear, 3-nerved, acute at the apex. 21. P. foliosus. Leaves with narrow blades, capillary or setaceous, 1-nerved or nerveless. 17. P. confervoides. With propagating buds or glands, or both. With buds, but without glands. Leaves serrulate, 3-7-nerved. 18. P. crispus. Leaves entire, with 3 principal and many fine nerves. 19. P. compressus. Commonly with glands, but no buds. Stems long-branching from the base; leaves lax, flat, 3-nerved, cuspidate. 20. Stems simple;
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1913
