Family 4. NAIADACEAE 
By Norman TAYLOR 
Submerged marine or fresh-water herbs with fibrous roots and slender, 
branching stems. Internodes spiny or unarmed. Leaves alternate, opposite, 
or whorled, the blades linear, spiny on the margins or the back, or both, acute 
or obtuse at the apex, sometimes tipped with one or more subulate spines, 
sheathing at the base. lLeaf-sheaths rounded or auriculate, entire or with 
spinulose teeth. The 2 intravaginal scales minute and hyaline. Flowers 
monoecious or dioecious, solitary in the axils. Staminate flowers with a 
double perianth-like envelope, the inner hyaline, the outer 4-horned or entire. 
Stamen 1, sessile. Anthers 1-4-celled. Pistillate flowers of a single pistil. 
Style short or wanting. Stigmas 2-4 and sometimes intermingled with 1-3 
Sterile, subulate, stigmoid processes. Fruit a sessile drupelet, the solitary 
seed filling the pericarp. ‘The seed apparently smooth and shining, or reticu- 
late with angled or roundish areolae. Embryo straight. 
Containing only the following genus: 
1. NAIAS L. Sp. Pl. 1015. 1753. 
Characters of the family. 
Type species, Naias marina 
Flowers dioecious ; internodes and back of the leaf spiny. 1. NM. marina. 
Flowers monoecious; internodes and back of the leaf unarmed. 
Leaf-sheaths merely rounded, not auriculate. 
Seeds shining ; anthers 1-celled. 2. MV. flexilis, 
Seeds reticulate ; anthers 4-celled. 
Marginal spines minute, subulate. 3. N. guadalupensis. 
Marginal spines conspicuous, triangular. 4. N. conferta. 
Leaf-sheaths auriculate. 5. WN. gracillima, 
1. Naias marina L. Sp. Pl. 1015. 1753. 
Naias marina gracilis Morong, Bot. Gaz. 10: 255. 1885. 
Naias marina recurvata Dudley, Bull. Cornell Univ..2: 104. 1889. 
Naias marina californica Rendle, Trans. Linn. Soc. II. 5: 398. 1899, 
Naias marina mexicana Rendle, Trans. Linn. Soc. II. 5: 398. 1899, 
Naias gracilis Small, Fl. SE. U. S. 40. 1903. 
Stems branched, sometimes dichotomously so, armed with brownish spinulose teeth on 
the internodes; leaves opposite or alternate, stiff or recurved, 0.5-3 mm. wide, 1-4.5 cm. 
long, with toothed margins and sometimes dorsally toothed on the midrib, the teeth usually 
triangular, apiculate, 1 mm. or more long; leaf-bases sheathing, the sheaths rounded, with- 
out teeth or rarely with a few short teeth; flowers dioecious; staminate flower 3-4 mm. 
long; anther 4-celled; pistillate flower usually 3-4 mm. long; stigmas 3, sometimes one 
shorter than the others; mature fruits apparently tesselated in dried specimens, smooth 
when fresh. : 
TYPE LOCALITY: Europe. : . . : ; . 
DISTRIBUTION : New York to California, south to Florida, southern California, and Mexico; 
Cuba; also Europe Asia, and Australia. . : 
ILLUSTRATIONS: Mem. Torrey Club 3?: pl. 65, Britt. & Brown, Ill. Fl. f. 179; Trans. Linn. 
Soc. II. 5: pl. 39, f. 1-9, 15, 26 and 30. . . 
The forms included under the names gracilis and recurvaia are fairly well marked, but not 
specifically so. The rest are mere leaf-forms. 
VoruME 17, Part i, 1909] 33 
