Segmebts of floating leaves wedge.shaped. (R. diversifolous, Schrank.)
Floating leaves truncate, fan·shaped _ 17. ripiphyllus.
Floating leaves suborbicular or with radiant segments.
Floating leaves rather thick, often hairy beneath 18. radians.
Floating leaves thin, glabroiis 19. Godronii.
Floating leaves wanting. (R. fœniculaceus, Gilibert.)
Leaves cincinate, with short, divaricate, crowded segments, usually surrounding the stem, and nearly in one plane, which is usually perpendicular to the stem 20. circnatus.
Leaves otherwise.
Leaves cuneato-flabelliform, on distinct pctioles, divisions short, lanceolate·linear 21. Bungei.
Leaves not cuneato-flabelliform, usually subsessile; divisions linear or capillary. (R. pectinatus, Dubois.) Subterrestrial. Leaf.segments linear, somewhat fleshy 22. cæpitous.
Aquatic. Leaf-segments capillary. (R. capillaceus, Thaillier.)
Carpels with a long beak 23. longirostis.
Carpels with a short beak.
Peduncles equalling or usually but little exceeding the leaves.
Segments of leaves rigid or diverging. (R. Rigidis, Pers., non Godr.)
Carpels not very numerous. Receptacle globular or oval.
Leaves distant, oval, with regular outline. Receptacle oval. 24. aspergillfolius.
Leaves with irregular outline or pencilled. Receptacle globular.
Segments of leaves diverging 25. trichophyllus.
Segments of leaves rigidlly converging 26. rigidus.
Carpels very numerous. Receptacle ovato· or elongato-conical 27. Rionii.
Segments of leaves weak and collapsing. (R..flaccidus, Pers.)
Leaves, flowers, and peduncles small or of moderate size.
Stamens few (5-12).
Receptacle nearly cylindrical. Stem slender, Stem filiform 28. confervoides.
Receptacle oblong. Stem slender, scarcely filiform 29. Drouetii.
Stamens Several 30 submersus
Leaves, flowers, and peduncles large 31. pseudofluitaus.
Peduncles long, usually exceeding the leaves.
Flowers large; petals 9-11.veiued. Carpels hairy 32. sphærospermus.
Flowers small; petals about 5-veined. Carpels glabrous.
Stamens longer than the head of carpels 33. salsuginosus.
Stamens shorter than the head of carpels 34. mannus.
Segments of submersed leaves long, usually stout, and subparallel. Receptacle glabrescent 35. fluitans,
