824 NAIADACE^. (pond-weed FAMILY.) 



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

 2-4-flowered, with short peduncles recurved iu fruit; sepals omte- 

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

 short, recurved beak — Summer. 



Var. lanccolatus, Boiss. Leaves lanceolate to linear-lanceolate 

 — The usual form in Syria. 



2, RUPPIA, L. Ditcii-Grass. 



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

 leaves. Perigouium 0. Stamens 3, with scale-like filaments, each with 

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

 narrowly oblong, . curved, dilated at cither 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. Albumen —Herbs with aspect 

 of Potamogcton pcctinatil§, growing in salt water. 



1. R. spiralis, L. 21 llamul. Stems filiform, much branched. 

 Leaves filiform. Peduncles Dery long after flowering, spirally twisted at 

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

 tapering at tip, one-fo\u'th to one-tenth as long as their stalk — April 

 to June — Salt water and salt marshes, coast. 



2. R. rostellatus, Koch. L. 21 Benzislud. Senmlud. 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. POSIDOl^IA, Koenig. Posidonia. 



Flowers polygamous, naked. Perfect floicers : 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. 

 Staminatefloioers : 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 flower 

 of the spikelet staminate, the rest perfect. 



P. occaiiica, L. 2Ji Stendra. Leaves about 13, nerved. Spike- 

 lets 3-flowered; connective of anthers aristate; fruit olive-shaped — 

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



4. ZAN]\I€HEL<L.IA, L. Hokned Pond-Weed. 



Flowers monoecious, 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 

 pedicellcd, 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- 



