Flora of the Palouse Region 13 



expanding: flowers small, perfect, spieate, green or red; parts of 

 flower in fours: ovaries 4, sessile, distinct, 1 -celled, i-ovuled. 



With both floating and submersed leaves, the former broad. 



Submersed leaves of two kinds, lanceolate, and oval or oblong; floating 



leaves broad-oval. P. AMPUFOWUS. 



Submersed leaves all alike, lanceolate; floating leaves narrow-elliptic. 



P. LOXCHITES. 



Leaves all submersed, linear. P. foliosus. 



P. amplifolius Tuck. Stemstout, simple or branched: floating leaf-blades 

 oblong-oval, acute, rounded at the base, 5-10 cm. long, on petioles about as 

 long; submersed leaves mostly linear-lanceolate, the uppermost frequently 

 oval or oblong; stipules large, 5-10 cm. long: spike stout, dense, 2-3 cm. 

 long, on stout peduncles: fruit large, 4-5 mm. long, with a broad beak. Col- 

 lected in a pond at Pullman by Henderson in 1892. Xot since seen. 



P. lonchites Tuck. Stems slender, flaccid, branched, .5-1 m. or more 

 long: floating leaves narrowly elliptic, pointed at each end, 5-10 cm. long: 

 many-nerved, narrowed at the base into a petiole about as long; submersed 

 leaves linear; stipules narrow, 3-8 cm. long: spike dense, 2-4 cm. long, on 

 stout peduncles: fruit about 3-4 mm. long. In ponds and pools, not common. 



P. foliosus var. californicus Morong. Stems slender, much branched, 

 flattened or somewhat winged, 30-50 cm. long, wholly submersed: leaves 

 linear, sessile, 2-5 cm. long, 1 mm. wide, 3-5-nerved, the midvein thick: 

 peduncles erect, club-shaped: spike containing 6-12 globose fruits, these 

 crested on the back, angled in front, short beaked, about 2 mm. long. Ponds, 

 common. 



21. NAIAS. 



Leaves opposite, alternate or verticillate, sheathing at the base: 

 flowers monoecious or dioecious, axillary, solitary, sessile or 

 pedicelled: sterile flower with a double perianth, the exterior one 

 entire, or 4-horned at the apex, the inner one hyaline, adhering to 

 the anther: fertile flower consisting of a single ovary: mature car- 

 pel solitary, sessile, ellipsoid. 



N. flexilis Rost. & Schmidt. Stems slender: leaves numerous, linear, 

 acute or acuminate, 1-2 cm. long, minutely serrulate, the sheath broadly- 

 oblong: fruit 3 mm. long, oblong-linear, tipped with the persistent style: 

 seed pale-brown, shining. Near Viola, Henderson. 



Family ii. AUSMACEAE. 



Aquatic or marsh herbs with fibrous roots, scape-like stems and 

 basal long-petioled leaves: inflorescence a raceme or panicle: flow- 

 ers regular, perfect, monoecious or dioecious, pedicelled; the ped- 

 icels whorled and subtended by bracts: sepals 3, persistent: petals 

 3, deciduous: stamens 6 or more: ovaries numerous or rarely few, 

 i-celled, usually i-ovuled: carpels becoming akenes in fruit; endos- 

 perm none. 



