824 NAIADACE^. (pond-weed FAMILY.) 



more or less crowded and recurved. Spikes from forks, nearly globular, 

 2-4-flowered, with short peduncles recurved in fruit; sepals ovate- 

 deltoid, acute; nutlets obovate, compressed, keeled at back, with a 

 short, recurved beak — Summer. 



Var. laiiceolatH§, Boiss. Leaves lanceolate to linear-lanceolate 

 — The usual form in Syria. 



2. RUPFIA, L. Ditch-Grass. 



Flowers 2, perfect, in a spike, at first enclosed in sheaths of floral 

 leaves. Perigonium 0. Stamens 2, with scale-like filaments, each with 

 2, large and separate anther-cells, diverging at base. Grains of pollen 

 narrowly oblong, curved, dilated at either end. Ovaries 4, at first 

 sessile, then long-pedicelled, 1-ovuled. Style 0, stigma sessile, peltate. 

 Ovule pendulous. Carpels pyriform, often oblique, crustaceous, dehis- 

 cent by a lid as germination begins. Albupien — Herbs with" aspect 

 of Potaniogetoii pcetiiiat«§, growing in salt water, 



1. li. spirali§, L. 1|; JlanvCd. Stems filiform, much branched. 

 Leaves filiform. Peduncles xevy long after flowering, spirally ticisted at 

 hase ; cells of anthers oblong; carpels ovoid, oblique, erect, gradually 

 tapering at tip, one-fourth to one-tenth as long as their stalk — April 

 to June — Salt water and salt marshes, coast. 



2. R.. rostellatHS, Koch. L. 2f Henzislud. Benmlud. Stems 

 filiform, much branched. Leaves filiform-setaceous. Peduncles not 

 elongated, spirally twisted after flowering; cells of anther nearly globu- 

 lar; carpels ovoid-semilunar, tapering, oblique at tip, one-fourth to one- 

 tenth as long as their stalk — Early summer — Beirut ; near Tor (Sinai). 



3. POSIDONIA, Koenig. Posidonia. 



Flowers polygamous, naked. Perfect flowers : stamens 3, anthers 

 sessile, the cells separated by an ovate-lanceolate or orbicular con- 

 nective; pollen confervoid, ovary ovoid, 1-ovuled; stigma sessile ; fruit 

 drupe-like, at length irregularly dehiscent; seed oblong, teretish. 

 ,Staminate flowers : stamens 3 ; ovary — Immersed, stout, marine herbs ; 

 root-stock thick, covered with the stumps of the withered leaves, which ■ 

 are ultimately resolved into fibres. Roots clustered, stout. Leaves 

 in two rows, sheathing, equitant, with minute auricles, short ligule, 

 and linear lamina with rounded entire tip. Scape terminal, over-top- 

 ped by the last branch, and so appearing lateral. The compound spike 

 and spikelets sheathed with large, leaf-like bracts, the uppermost flowei' 

 of the spikelet staminate, the rest perfect. 



P. oceaiiica, L. 11 Stenura. Leaves about 13, nerved. Spike- 

 lets o-flowered ; connective of anthers aristate ; fruit olive-shaped — 

 Summer — At the bottom of the sea, to a depth of 30 metres. 



4. ZANXICHEL.L.IA, L. Horned Pond-Weed. 



Flowers moncecious, the staminate and pistillate close together, the 

 staminate distinct, at length long-peduncled. Staminate flowers : 

 perigonium 0; anthers (sometimes 2), the two cells adnate to the ex- 

 current connective. Pistillate flowers : perigonium membranous, cup- 

 shaped, subtending the base of the carpels. Carpels 4-8, sessile or 

 pedicelled, oblong, flattened; style short or elongated ; stigma peltate ; 

 ovule 1, suspended. Mature carpels coriaceous, dehiscent at germina- 

 tion into two valves. Seed oblong, with thin testa, albumen 0. Coty- 



