392 
NAIADACEJ3. 
\_Rotamogeton . 
reaching a length of several feet. Leaves alternate, lanceolate, nar- 
rowed gradually from the middle to both ends, all submerged, very thin, 
bright green, 3-6 in. long, f-1 in. broad, with 3-6 veins on each side of 
the midrib, connected by distinct transverse veinlets, the edge minutely 
crispato-denticulate ; stipules above 1 in. long, free, lanceolate. 
Peduncle stout, 2-4 in. long. Spikes dense, 1-1 \ in. long. Drupes 
smaller than in P. natans and not keeled. 
Mauritius, in inland lakes and slow streams. Cosmopolitan. 
3. P. crispus, Linn. ; Kunth , JEnum . iii. 133. Stems slender, copi- 
ously branched. Leaves alternate, ligulate, obtuse, sessile, all sub- 
merged and very thin, bright green, 1-2 in. long, in. broad, with a 
single intra-marginal nerve, the edge crisped and denticulate ; stipules 
small, free, obtuse, evanescent. Peduncle slender, curved, 1-ly in. long. 
Spike J-j- in. long, rather lax. Drupes % in. long, oblique ovoid, with 
a distinct beak. P. tuberosus, Roxh. ; Bojer , Hort. Maur. 358. 
Mauritius, in inland streams. Cosmopolitan. 
4. P. pectinatus, Linn.; Kunth , Knum. iii. 137. Stems slender, 
several feet long, copiously branched, forming dense masses. Leaves 
sessile, narrow ligulate, 1-nerved, 4-8 in. long, yV'i'V i n - broad ; sti- 
pules J— 1 in., adnate to the edge of the blade. Peduncle slender, an 
inch long. Spike as long as the peduncle, interrupted. Drupes % in. 
long, nearly globose, with a short central beak. 
Mauritius, in inland streams and in the sea at Fort William and Canonier 
Point. Cosmopolitan. 
2. RUPPIA, Linn. 
Flowers hermaphrodite, 2 or more on a peduncle which at first is 
enclosed in a sheath formed by the stipules connate with the base of the 
leaf. Perianth 0. Stamens 2 ; filaments very short ; anthers 2-celled. 
Ovary of 4 free carpels ; ovules solitary in each carpel, pendulous : style 
0 or short ; stigma peltate, oblique. Drupes oblong, long-stalked. — 
Salt-water herbs, with slender branched stems forming dense masses 
and filiform l-nerved. leaves. Distrib. Cosmopolitan. Species, or 
rather subspecies, 3. 
1. R. rostellata, Koch in Reich. Ic. ii. 66, t. 174. Stems very slen- 
der, rooting at some of the joints and sometimes forming tubercles from 
which new plants spring. Leaves 1-3 in. long, y 1 ^ in. broad, with a 
narrow stipular sheath about \ in. long. Peduncles short, not spirally 
twisted. Drupe T x ¥ in. long, oblique globose, narrowed into a distinct 
beak. R. maritima, Kunth, Enum. iii. 123, in part; Bojer , Hort. Maur. 
358. 
Mauritius and Rodriguez, in the sea and brackish ditches. Cosmopolitan. 
