174 SUMMER FLOWERS. 



(261) Polygonum — perianth five-parted, the segments nearly 



equal. 



57. Santalaceous Plants. Santalace^. 



(262) Thesium — leaves alternate, entire, without stipules. 



58. Euphorbiaceous Plants. EurnoRBiACEiE. 



(263) Euphorbia — flowers collected in heads, surrounded by a 



4-5-toothed perianth-like involucre, enclosing several male 

 flowers (each a single stamen, with jointed filament), and 

 one female (a solitary three-celled stalked ovary). 

 (264<) Mercurialis — herbs, with the male and female flowers se- 

 parate, dioecious or monoecious. 



59. Aristolochiaceous Plants. Aristolqchiace^. 



(265) Aristolochia — perianth tubular, very oblique ; stamens six. 



60. Trilliaceons Plants. Trilliace^. 



(266) Paris — perianth of 8-10 narrow, spreading or reflexed seg- 



ments. 



61. Dioscoreaceous Plants. Dioscoreace^. 



(267) Tamus — perianth of six segments. 



62. Orontiaceous Plants. ORONTiACEiE. 



(268) Aeorus — spathe (flower sheath) a continuation of the scape, 



and similar to the leaves, not convolute. 



63. Typhaceous Plants. Typhace^. 



(269) Typha — spadix (flower spike) cylindrical. 



(270) Sparganium — spadix spherical. 



