108 NAIADAflMC. (iMtNKWKKK KAMII.Y.) 



1. TYPHA, 'ruurii. Cat-taii.. 



Flowers donsoly crowded on a loiiji rvlindrical terminal s]iadix, enveloped 

 in <()|ii(ins pajipns like liairs; tlie sterile ones sessile on the npper jiart of the 

 wpadix, tiie fertile on slender stalks. Style (iliforin.: sti<;nia lateral. — Stems 

 Htrai^lit, from a tliiek riii/.oma, clntlieil Itelow with the sheatliinj^ liases of the 

 elonjjatcd linear leaves. Spathes lirai-t-like and deeidnous, or none. 



1. T. latifolia, I-. stem terete, jointeil Itelow; leaves nearly as long a.s 

 the stem, erect, Hal, retienlated and .somewhat glancous ; sterile and fertile 

 portions of tiie spadix eontigiions, eylindrieal. — Margins of jionds and rivers, 

 Florida, and northward. July - Angn.st — Stem 4°-6° liigli, seape-like 

 ahovc. Leaves alioiit 1' wide. Sjiadix ahout 1° long. — T. angnstifolia, Z,., 

 if found within our limits, may he known iiy narrower leaves wliieli are chan- 

 nelled near the base, and hy tiie interxal which sejiarates the sterile and fer- 

 tile jwrtions of the spadix. 



2. SPARGANIUM, L. Bi r-reet). 



Flowers den.sely crowded in gloliular heads, surrounded by several scales 

 like a calyx ; the upper heads sterile, naked, the lower fertile and commonly 

 bracted. Ovarv sessile, pointed by the short persistent style. Stigma lateral 

 — Marsh or aipiatic plants, with erect stems, and long strap-shaped sessile 

 leaves, the lowest slieathing. Heads of flowers scattered. 



1. S. simplex, Huds. Leaves flat, obtuse, the upper concave and clasp- 

 ing, the lower sheathing ; heads scattered, the lowest larger and pistillate, the 

 others staminate ; scales wedge-shajjed ; stigma subulate, simple. — Touds and 

 ditches. July. — Stem 1° - 2° high. Heads 6" - 10" broad. 



Order 140. NAIADACE^. (Poxdweed Family.) 



Aquatic herbs, with slender jointed leafy immersed stems, and per- 

 fect or monoecious or dioecious flowers, destitute of floral envelopes, or 

 with scale-like sepals. Stamens 1 - 4 : anthers 1 - 4-celled. Ovary 1- 

 celled, forming a 1-seeded achenium in fruit. Stigmas 1-4. Seed 

 witliout albumen. Embryo straight, curved, or coiled. — Leaves 

 sheathing, or with sheathing stipules. Flowers commonly enclosed 

 in a spatlie. 



Synopsis. 



* Flowers monfecioiis or dioecious. 



1. NAI.\S. Sti(fma8 2-4. Flowers naked. Leaves opposite or whorled. 



2. ZOSTERA. Stigrnas 2. Flowers enclosed in a spathe. Leaves alternate. 



3. Z.\N"NICHF:lLIA. stigma single, peltate. Ovaries 4, from a cup-like involucre. 



4. TH.ALASSIA. Flowers dioecious. Sepals 3 Anthers 9, sessile. 



* * Flowers perfect. 



5. RUPPIA. Fruit louK-peduncled, umbellate. Calyx and corolla none. 

 C. POTAMOGETON. Fruit sessile, spiked. Calyx 4-leaved. 



