672 Obdkb 134.— NAIADACE^E. 



2. SPAR'GANUM, L. Burr Reed. (Gr. CTtdpyavov, a band or fit- 

 let; in reference to the long, ribbon-like leaves.) Spadiccs many, glob- 

 ous, the lower fertile, the upper consisting of numerous stamens with 

 Bcalcs intermixed ; filaments slender ; anthers oblong-linear, 2-celled ; 

 $ pistils numerous, sessile, each surrounded by 3 or 6 scales, which 

 represent a perianth ; stigma ligulate, unilateral, fruit nut-like, sessile, 

 1-seeded. — U Aquatic herbs. St. leafy, simple or branched. Lvs. 

 long, linear, sheathing at base. 



§ Stigmas mostly 2. Stems of the inflorescence! branching. Erect No. 1 



j Stigmas always single. Stem simple. — Erect. Heads largo (half inch diam.) No. 2 



— Floating or erect. Heads small Nos. 8, 4 



1 S. ramosum Huds. Lvs. triangular at base, their sides concave ; common 

 flower-stalks branched; stig. 2, linear. — Grows in pools and ditches, where it U 

 conspicuous among other reedy plants for its globular hurra of flowers. Stem 

 1 — 2f high, flexuou3, round, with a few branches above. Leaves \ — 2f long, 

 4 — 8'' wide, linear, arising abovo the stem, triangular towards tho base, and 

 Bword-form upwards, tapering, but obtuse. Heads of flowers light green ; fertilo 

 ones 2 — 5, 6" diam., the lowest generally raised on a short, axillary stalk; sterile 

 ones above, more numerous, smaller, sessile. Aug. 



2 S. simplex Smith. Lower lvs. equal with, or exceeding tho ptem, which is 

 nearly simple, floral ones concavo at baso and erect ; stig. always simple, ovate- 

 oblong, oblique, scarcely more than half the length of the style. — Ponds and 

 lakes. Stem 1 — 2f high, simplo or divided at base. Leaves mostly radical, 

 1 — 2if by 3", carinate at base. Fertile heads sessile, generally 3, 6 to 8" diam., 

 below the several barren ones, with tho eimplo styles conspicuous. Aug. (S. 

 Americanum Nutt.) 



3 S. natans L. Lvs. floating, flat ; common flower-stalk simple ; stig. ovate, very 

 short ; head of sterile fls. subsolitary ; fruit beaked and stipitate. — Lakes and pools, 

 U. S. and Brit. Am. Stem long and slender, and, with the leaves, floating upon 

 the surface of tho water. Leaves thin and pellucid. Heads of fertile flowera 

 axillary, generally 2, small, mostly sessile. Sterile cluster terminal. Aug. 



4 S. angustifolium Mx. Slender, weak, simple, erect or floating ; lvs. narrowly 

 linear, shorter than the stem when erect, elongated when floating; heads very 

 small, axillary, the lower pedunculate ; stigma single, short ; fir. scarcely beaked, 

 sessile. — N. Eng., N. Y., Can., pools and streams. Sts. 1 to 2f long, lvs. 1 to 3 to 

 9' or more, obtuse. lids, scarce a fourth of au inch diam. 



Order CXXXIV. NAIADACEJ5. Naiads. 



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

 Flowers perfect or diclinous, naked or with a 2 to 4-parted perianth. Stamens defi- 

 nite. Ovaries free, sessile, 1-ovuled. Stigma simple, often sessile. Fruit indehis- 

 oent Seed without albumen, with a straight or curved embryo. 

 (ientra 9, epeci-e-a 60, In waters and marshes, salt or fresh in nil countries. 



* Flowers axillary, sessile, tho staminato reduced to a single stamen (a). 



a Fertilo flowers reduced to a singlo pistil, with 2 or 3 stigmas. Lvs. opposite. .Saj.u. 1 



a Fertilo flowers with about 4 pistils in a cup, with as many stigmas Zaxioiiklli a. 9 



• Flowers spadaceous, or 2 to 20, sessilo on a spadix or spike (b). 



b Flowers monoecious, seated in 2 rows on tho side of a linear, flat spadix Zostera. S 



b Flowers perfect, naked, 2 to 5, 4-merous ; fruit raised on slender stipes Euppia. 4 



b Flowers perfect ; perianth 4-sepalod j stam. 4. Pistils and achenia 4.. Potajjoohton. 5 



1. NA'JAS. L. Water Nymph. (Gr. vow, to flow ; hence Nai'c, or 

 Na£<$£$\ Nymph of the waters ; from the habitat.) Flowers axillary, 

 sessile, solitary, the <$ reduced to a single stamen ; filament slender, 



