CLXx. NAiADACE^. (J. D. Hooker.) 563 



or submerged or floating, base sheathing ; stipules or within the sheath. 

 Flowers inconspicuous, usually green, 1-2-sexual. Pericmth 0, or tubular, 

 or of 3-4 inferior valvate segments. Btamens hypogynous ; anthers 

 1-2-oelled. Ovaty of 1-4 1-ovuled carpels, style long or short, stigma 

 various ; ovule erect or pendulous. Fruit of 1-seeded utricles achenes or 

 drupelets. Seed exalbuminous ; embryo straight or curved, radicular end 

 very large. — Temperate and tropical ; genera 16, sp. about 120. 



* Stigmas discoid or deourrent on the ovary. 



■}■ Ferianth of sepals or scales. Flowers hisexual. 



Marsh herbs. Sepals 6, herbaceous green 1. TEiOLOCHiif. 



Aquatics. Sepals 1-3, white, membranous 2. Apokoobton. 



Aquatics. Sepals 4, herbaceous, green 3. Potamooeton. 



ff Ferianth 0. Flowers uni- or hi-sexual. 



Aquatics. Stamen 2. Carpels stipitate 4. RuppiA. 



Aquatics. Stamen 1. Carpels sessile . . ^ 5. Zanniohbllia. 



** Stigmas subulate or capillary. Flowers unisexual. 



Fresh or brackish aquatics. Perianth hyaline 6. Naias. 



Marine. Perianth 7. Cymodooea. 



1. TRXeiiOCHXXT, Unn. 



Scapigerous marsh herbs. Leaves rush-like, flat or terete. Flowers 

 small, bisexual, spicate or racemose, 2-bracteate. Perianth-segments 3 or 6, 

 herbaceous, concave, deciduous. Btamens 6, inserted on the base of the 

 segments; anthers didymous, sUts extrorse. Car^eZ* 6, 1-celled, 1-ovuled, 

 3 alternate often imperfect ; styles short, often connate, stigmas peni- 

 cillate; ovules basilar, erect, anatropous. Fruit of 3 or 6 free or 

 connate achenes or follicles with recurved tips. Seed erect; embryo 

 straight. — Genus cosmopolitan; species about 12. 



1. T. palustre, lAnn. Sp. PI. 338 ; leaves J-terete throughout, fruit 

 clavate, carpels 3 slender attached to the axis by a point. Kvmth Enum. 

 iii. 143 ; Beichb. Ic. Fl. Qterm. vii. t. 51 ; Boiss. Fl. Orient, v. 13. — Tri- 

 glochin, Qriff. Notul. iii. 204 ; Ic. PI. Aeiat. t. 271 . 



Temperate and Aipinb Himalata, and Wbstben Tibet, alt. 8-15,00C 

 ft. — DiSTEiB. N. temp, regions and S. America. 



Stem 6-24 in., tuberous and stoloniferous. Leaves 2-12 in., flaccid. Scapi 

 slender ; raceme elongating after floweriiig, pedicels short. Perianth green, margins 

 purplish. Anthers purple. Fruit \ in. long, appressed to the rachis; carpels 

 dorsally terete. 



2. T. maritimum, lAnn. Sp. PI. 339; leaves slightly flattened at 

 the tip, fruit oblong of 6 separable carpels. Kv/nth Enwm. iii. 145 ; 

 Beichb. Ic. Fl. Germ. vii. t. 52 ; Boiss. Fl. Orient, v. 13. 



Tbmpekatb and Aipine Himaiata, and Westeen Tibet, from 12,000-16,000 

 ft. — DiSTElB. N. temp, regions. 



Larger, stouter, and more tuberous at the base than T. palustre. Scape stout, 

 curved ; raceme longer, but not elongating so much in fruit ; flowers larger ; fruit 

 \ in., not appressed to the scape, carpels grooved on the back. 



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