S26 H^lApACEiE. (pond-weed FAMILY.) 



* Boot-stoch composed of short and long segments, with short, erect tranches. 

 Leaves linear, furnished with air-ducts. Flowers solitary at ti]} of 



tranches similar to the sterile ones, or in pseudo-lateral clusters. 



1. C. nodosa, XJcria. If Koot-stock .002 thick, creeping ou the 

 mud. Leaf -scars forming closed rings; sheath cylindrical, much 

 longer than diameter, auricled; lamina 7-nerved, denticulate above; 

 keel of semi-ovate carpel entire or repand — ^xwioiQx — Ras-Beirut. 



2. C rotundata, Ehrh. et Hempr. % Root-stock .002 thick, 

 creeping on the mud. Leaf -scars forming closed rings ; sheath cylindri- 

 cal, much longer than diameter, auricled; lamina 7-1 3-nerved, denticu- 

 late above ; keel of carpel acutely coarse-dentate — Summer — Tor, and 

 probably elsewhere. 



* * Boot-stocJo as in last. Lamina of leaves terete, oltusish at tip, appear- 

 ing dorsal owing to the conspicuous auricles at tip of sheath (ichich is 

 p}ersistent after the fall of the lamina) furnished with air-ducts. Floicering 



Iranch ^-ranlced lelow. InHorescence spiTced-cymose. 



3. C. isoetifolia. 1i Root-stock as in last. Leaf-scars forming 

 openrmg^', sheaths cylindrico-obconical ; lamina fleshy, bright green, 

 drying to a i^ale, glaucescent tint, longitudinally grooved, retuse and 

 3-toothed at tip — Summer — Tor and 'Aqabah, and probably elsewhere. " 



*,* * Moot-stoch loith long, often much branched tranches, woody, terete. 

 Lamina of leaves troad-linear, destitute of air-ducts. Inflorescence as * . 



4. C. ciliata, Forsk. 11 Qushr. Branches composed of numer- 

 ous, short internodes. Leaf-scars forming closed rings; sheaths 

 obconical, at length 2-3 times as long as broad, with small auricles; 

 lamina 23-25-nerved, with scarious-margined, acute teeth toward 

 notched tip. Staminate flowers and fruits as yet unknown — Summer 



— Tor, and probably elsewhere. 



y. HALOD1JLE, Endl. Halodule. 



As in Cymodocea, excejDt that one anther is exserted as much 

 beyond the other as the length of the latter. Carpel with one stigma 



— Marine plants, with slender root-stock, ringed by the prominent scars 

 of fallen leaves. Sheaths cylindrical, 2-auricled, ligulate. -Lamina 

 linear, with 2, acute, lateral teeth at tip, and a median and 2 lateral 

 nerves, secondary nerves obscure. Staminate flower on a rather 

 long peduncle ; pistillate with only the tips of the stigmas exserted.' 



H. uninervis, Forsk. 2f Lamina scarcely produced into a 

 rounded tip between the teeth, often tridentate by the excurrence of 

 the median nerve — Summer — Tor. 



8. NAIAS, L. Naiad. 

 Flowers monoecious or dioecious, solitary or clustered at the base 

 of the branches. Staminate fiowers: outer involucre calyptra-like, 

 2-4-cleft at tip, or tubular, tapering and denticulate at tip, the inner 

 coalesced with the anther, dehiscent with it. Pistillate fiowers : stig- 

 mas subulate, papillose along their inner face — Aquatic, submerged 

 annuals, with stiff, branching, slender stems, linear, spiny-denticu- 

 late, or nearly entire, nearly opposite, leaves, which are dilated at base 

 and obliquely decussate, the succeeding pairs winding spirally around 

 the stem, the young leaves clustered in the axils. 



