GENERA OR FAMILIES. 175 



64. Pistiaceous Plants. PISTIACE.E. 



(271) Lemna flowers monoDcious ; 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. 



66. Hydrocharidaceous Plants. HYDROCHARIDACE^E. 



(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. IRIDACEJE. 



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



three, petal-like, arching over the stamens. 



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



a somewhat oblique two-lipped arrangement, 



68. Orchidaceous Plants. ORCHIDACE.E. 



* Anther 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. 



