Ruppia.] NAIADACEjE. 437 



sessile peltate ; ovules solitary, pendulous. Drupelets stipitate, ovoid, 

 carried up on the greatly lengthened usually spirally coiled peduncle. 

 Seed pendulous, testa thin ; radicle large ovoid, cotyledonary end small 

 hooked sub terminal. — Distrib. Temp, and trop. regions ; species 1 or 

 more. — Etym. H. B. Ritppius, a botanical author. 



R. marit'ima, L. ; leaves opposite and alternate. 



Brackish ditches, &c, N. to Shetland ; rare in W. Scotland ; Ireland ; 

 Channel Islands ; fl. July-Sept. — Habit of Potamoge'ton pectina'tus. Stem 

 filiform, much branched, 2 ft. and upwards. Leaves 1-3 in. ; the first leaf of 

 each axillary shoot is opposite to a narrow obtuse or notched cellular scale 

 J in. long arising from the base at the side next the axis. Peduncle short 

 and straight in flower, fruiting 5-6 in. Drupelets §-£ in., green, beaked, 

 pedicel 1-2 in. — Distrib. All shores temp, and trop. 



K. marit'ima proper; sheaths inflated, fruiting peduncles spirally coiled, 

 anther-cells oblong, drupelets nearly straight, beak shoit. R. spira'lis, 

 Hartm.— Orkney to Somerset ; rare in Ireland. 



Sub-sp. E. rostella'ta, Koch; sheaths appressed, fruiting peduncles short 

 flexuous, anther-cells subglobose, drupe gibbous, beak longer. Common ; 

 flowers earlier. — Var. na'na, Syme, has creeping stems buried in the mud, 

 and very short pedicels. Orkney. 



5. ZANNICHEL'LIA, L. HORNED PONDWEED. 

 Slender water-plants. Leaves submerged, usually opposite, linear ; 

 stipules adherent to the sheathing leaf-base. Flowers minute 1- or 2- 

 sexual, solitary or in pairs, axillary, situated in a cup-shaped sheath. Sta- 

 men 1 ; anther 2- celled, sagittate, cells adnate to the slender filament, 

 dehiscence lateral, connective excurrent ; pollen globose. Carpels 4-6, 

 styles long or short, stigma peltate persistent ; ovule pendulous, orthotro- 

 pous. Drupelets 4-5, sessile or stalked, oblong, curved. Seed pendulous, 

 testa membranous ; radicle large, clavate ; cotyledonary end slender, twice 

 folded. — Distrib. Temp, and trop. regions; species 1 or several. — Etym. 

 Zannichelli, a Venetian botanist. 



Z. palus'tris, L. ; aehenes curved, keel smooth tubercled or crenulate. 



Fresh and brackish ditches and pools, N. to Orkney ; rare in W. Scotland ; 

 Ireland ; Channel Islands ; fl. May-Aug. — Annual. Stem 3-6 in., filiform or 

 setaceous; branches divaricate. Leaves 1-3 in., opposite, subwhorled, often 

 capillary. Flowers sessile or shortly pedicelled. Aehenes about T J j in., 

 narrow. — Distrib. Europe, N. Africa, Siberia, India. — The following forms 

 are defined by Mr. Baker. 



Z. palus'tris proper ; drupelets 2-4 sessile, back rarely crenulate, style half 

 as long, stigma small and crenulate, filament ^-1 in., anther 4-celled. — 

 Z. macroste'mon, Gay. 



Sub-sp. Z. brachyste'mon, Gay ; drupelets 2-4 nearly sessile, back crenate, 

 style about half as long, stigma large crenulate, filament §-^ in., anther 

 2-celled. Z. palus'tris, E. B. ; Z. ma'jor, Bonn. — Common. 



Sub-sp. Z. pedunccxa'ta, Reichb. ; drupelets pedicelled, back strongly muricate, 

 style about as long, stigma large crenulate, filament j-§ in., anther 2-celled. 

 Z. pedicella'ta, E. B. 



