48. Either terrestrial plants or if aquatic then not completely submerged (or only 



briefly so at some seasons), the flowers always aerial or with a less 

 bizarre habit (50) 



49(48). Leaves whorled; plants usually seemingly free-floating 



60. Ceratophyllaceae, p. 912 



49. Leaves alternate, distichous; plants attached to rocks and usually in swift- 



flowing water 68. Podostemaceae, p. 993 



50(48). Stem-parasites not in contact with the soil; vegetative parts threadlike.... 

 63. Lauraceae, p. 961 



50. Nonparasitic or if parasitic then appearing rooted in soil (51) 



51(50). Shrublets or subshrubs with creeping underground organs, forming 

 colonies on low salty ground near and along the Texas coast; 

 leaves well-developed (cf. Salicornia where they are mere scales), 

 opposite, fleshy, linear; pistillate flowers aggregated into and largely 

 sunken in the axes of short axillary inflorescences; staminate flowers 

 in spikelike axillary inflorescences 54. Bataceae, p. 868 



51. Habitally diverse, if fleshy then having leaves reduced to scales or alternate 



leaves or the inflorescences different from Batis (52) 



52(51). Corolla absent, the flower either with no perianth or with only one series 

 of perianth parts (sepals or "tepals"); (also see here Rumex with 2 

 dissimilar whorls or sepals) (53) 



52. Each flower with both calyx and corolla or occasionally in families with uni- 



sexual flowers the petals absent from the pistillate ones, or in some 

 taxa petals present only in the chasmogamous flower but absent 

 from cleistogamous ones (95) 



53(52). Trees with flowers and fruits small and numerous in spherical heads; 

 leaves palmately lobed (54) 



53. Trees, shrubs, herbs or vines with flowers not in spherical heads or if so 



then leaves not palmately lobed (55) 



54(53). Bark furrowed; leaves deeply 5- or 7-lobed to resemble a star, smooth 

 and shiny (genus Liquidamhar of). ...71. Hamamelidaceae, p. 1011 



54. Bark exfoliating in thin sheets; leaves 3- or 5-lobed, usually with broad 



rounded .shallov sinuses, the undersurfaces usually pubescent 



72. Platanaceae, p. 1012 



55(53). Sepals coalescent at least near their bases either above the receptacle in 

 hypogynous flowers or above the floral cup or hypanthium in peri- 

 gynous flowers or above the ovary in epigynous ones (56) 



55. Sepals free from each other either completely to the receptacle in hypogynous 



flowers or above the ovary in epigynous ones, or sepals absent (67) 



56(55). Ovary completely inferior (57) 



56. Ovary superior or only partly inferior near the base (60) 



57(56). Herbs usually growing partially submerged or in mud but the flowers 

 aerial (58) 



57. Plants never aquatic (59) 



58(57). Leaves (at least the immersed ones) pinnatifid to capillary-dissected; 



staments more than 1; ovary 2- to 4-celled 



96. Haloragaceae, p. 1201 



58. Leaves all entire; stamen 1; ovary 1-celled 97. Hippuridaccae, p. 1208 



28 



