174 SUMMER FLOWERS. 



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



equal. 



57. Santalaceous Plants. SANTALACE^E. 



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



58. Euphorbiaceous Plants. EUPHORBIACE^E. 



(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. ARISTOLOCHIACEJS. 



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



60. Trilliaeeous Plants. TRILLIACE.E. 



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



ments. 



61. Dioscoreaceous Plants. DIOSCOREACE.E. 



(267) Tamus perianth of six segments. 



62. Orontiaceous Plants. ORONTIACE^E. 



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



and similar to the leaves, not convolute. 



63. Typhaceous Plants. TYPHACE^E. 



(269) Typha spadix (flower spike) cylindrical. 



(270) Sparganium spadix spherical. 



