320 ORDER 133. NAIADACE.E. 



Perianth of a few scales, or a tuft of hairs, or 0. Stamens 1 4, with long, 

 slender filaments. Ovary with 1 pendulous ovule. Seed albuminous, with 

 an axial embryo. Fig. 211. 



1. TYPHA, L. CAT-TAIL. REED-MACE. Spadix long, cylindric, dense, 

 sterile above. $ Sta. 3 together, united into a common filament ? Ova. 

 pedicellate, surrounded at base by a hair-like pappus or calyx. U Fls. very 

 numerous, packed solid in the large brown terminal spadix. 



1 T. latifolia L. Leaves linear, flat, exceeding the stem ; spadix cylindric, the 



sterile and fertile contiguous. Tall and smooth, 3 5f, in swamps. 



2 T. aiiff ustifolia L. Leaves linear, channelled, exceeding the stem ; spadix cylin 



dric, the sterile pome remote from the fertile. Swamps. 2^f. 



2. SPARGANIUM, L. BURR REED. Spadices or globular heads 

 many, the lower fertile, consisting of sessile pistils, each with 3 6 sepals, 

 and forming 1-seeded nuts. Sterile heads a mass of stamens with scales 

 intermixed, it ? August. 



* Stigmas mostly 2. Stems of the inflorescence branching, erect No, 1 



* Stigma always single. Stem eubsimple, erect or floating Nos. 2, 3 



1 S. eurycarpum Eng. Stout, 1 3f; Ivs. very long, carinate beneath ; fruit heads 



1', nuts large, obpyramidal, truncate, sessile ; sterile heads numerous. Borders of 

 rivers and ponds, N. Eng. to Pa., and W. (S. ramosum C-B.) 



2 S. simplex Hud*. Erect, slender, 1 2f; leaves triangular at base, long and nar- 



row ; sepals spatulate, denticulate ; nuts beaked and stiped ; heads 6 8" broad, the 

 S more than the 9 . Ponds and bogs, N. and W. 

 /3. natans. Leaves floating, flat ; stigma shorter than the style ; heads few. 



3 S. minimum Bauhiii. Slender, weak, simple, erect or floating; leaves nan-ow, 



flat ; heads few, axillary, small (3 4") ; fruit scarcely beaked, sessile. Streams, N. 

 Eng., and W. (S. angustifolium C-B.) 



ORDER CXXXIIL NAIAD ACE^E. NAIADS. 



Water plants with jointed stems, and sheathing stipules, or sheathing 

 petioles. Flowers perfect or diclinous, naked or with a 2-4-parted peri- 

 anth. Stamens definite. Ovaries free, sessile, 1-ovuled. Stigma simple, 

 often sessile. Fruit indehiscent. Seed without albumen, with a straight 

 or curved embryo. 



Flowers axillary, sessile, the staminate reduced to a single stamen. . .(a) 



a Fertile flowers reduced to a single pistil, with 2 or 3 stigmas. Leaves opposite... NAJ AS. 1 



a Fertile flowers with about 4 pistils in a cup, with as many stigmas ZANNICHELLIA. 2 



Flowers spadaceous, or 2 20, sessile on a spadix or spike... (6) 



b Flowers monoecious, seated in 2 rows on the side of a linear, flat spadix ZOSTERA. 3 



b Flowers perfect, naked, 25, 4-merous. Fruit raised on slender stipes RUPPIA. 4 



ft Flowers perfect. Perianth 4-sepalled. Stamens 4. Pistils and achenia 4 POTAMOGKTON. 5 



1. NAJAS, L. WATER NYMPH. $ Fl. a solitary stamen, in a little 

 hooded spathe. ? Fl. a naked pistil with 2 4 subulate stigmas. Fr. a 

 little 1-seeded, drupe-like nutlet. ? Entirely submersed. Lvs. opposite, 

 linear, broader at base, toothed. Flowers axillary. 



1 N. major All. Stem frail and slender, 1 3f ; le'aves V and less, crowded above with 

 conspicuous spinulous teeth ; nutlets ovoid, H" long. N. Y. (Clinton). 



