KEY. 



205 



Stamens 2, borne on one side of the stalk of the 

 ovary, with their long filaments united below (and 2 short, 

 sterile filaments sometimes on each side). Stigmas 2, sessile, 

 recurved. Flower naked, from a tubular sac-like involucre. 

 Leaves 2-ranked, dilated iuto a sheathing base, rigid and di- 

 chotomously dissected into filiform divisions. Herbs small, 

 submersed, adhering to stones and pebbles. 



Fodostemon ceratophyllum, Mx. 



550. The whole spadix covered with stamens and pistils, 

 intermixed. Ovary roundish ; stigma sessile. Lower flow- 

 ers always perfect, the upper often of stamens only. Scape 

 thick. Spathe broad, open, green without, white within. 

 Leaves cordate. In cold bogs. Calla palustris, L. 



Spadix club-shaped, the upper third naked. Flow- 

 ers, by abortion, dicecious, or monoecious; when numerous, the 

 pistillate in the lower, the staminate in the middle third of 

 the spadix. Leaves compound, of 3, or of 7-11 leaflets. 

 Scape sheathed by the petioles of the veiny leaves, and there- 

 fore stem-like. Arisaema, Martins (812). 



(Arum, L.) 



«l*il. (540.) L Flowers perfect, or sometimes polyga- 

 mous 552 



II. Flowers strictly monoecious. 



Scleria and Carex (see both in 821). 

 III. Flowers strictly dioecious. Glumes imbricated 

 or alternate. Perianth of united scales (perigynium), sac- 

 like, enclosing the achenium. Carex (821). 

 Gr. T. Yl. 



552, Glumes of the spikes 2-rowed. Flowers perfect. 



553 

 Glumes imbricated in several rows. Flowers per- 

 fect, or polygamous 555 



553, Inflorescence terminal. Perianth none 554 



Inflorescence axillary. Perianth of 6-10, down- 

 wardly barbed bristles. Peduncles solitary, axillary, from 

 the sheaths of the leaves. Dulichium spathaceum, Pers. 



Gray, T. L 

 «>«S4. Spikes 2- to many-flowered, collected in an involu- 

 crate, or compound, terminal umbel or head. Cyperus. 



Gr. T. I. 



