GENERA OR FAMILIES. 175 



64. Pistiaceous Plants. Pistiace^. 



(271) Lemna — flowers monoecious ; spathe urceolate ; stamens 1-2. 



65. Naiadaceous Plants. Naiadace^. 



(272) Potamogeton — flowers perfect, in pedunculated spikes or 



heads. 



(273) Zannichellia — flowers monoecious, axillary and sessile. 



6Q. Hydrocharidaceous Plants. HYORocHARiDACEiE. 



(274) Stratiotes — stem scarcely any ; leaves sword-shaped, tufted, 



radical, submerged ; flowers polyandrous. 



(275) Hydrocharis — stem root-like, bearing tufts of roundish 



floating leaves ; flowers 9-12-androus. 



(276) Anacharis — stems submerged, branched, with small oppo- 



site or whorled leaves ; flowers minute, with nine stamens, 

 ©r three styles. 



67. Iridaceous Plants. Iridacej^. 



(277) Iris — perianth six-leaved, the tliree outer larger ; stigmas 



three, petal-like, arching over the stamens. 



(278) Gladiolus — perianth six-leaved, the divisions similar, witli 



a somewhat oblique two-lipped arrangement, 



68. Orchidaceous Plants. ORcniDACEiE. 



* AntJier single, the pollen simple, or consisting of granules 

 in a slight state of cohesion. 



(279) Listera — perianth ringent ; lip deflexed, linear, or oblong, 



two-lobed ; anther parallel with the stigma, enclosed in a 

 hood. 



(280) Epipactis — perianth patent ; lip interrupted, the basal 



division concave, terminal one larger, with two projecting 

 plates at its base above ; anther terminal. 



