NAIAS FAMILY 



93 





2. Naias flexilis (Willd.) Rost. & Schmidt. 



Slender Naias. 



Fig. 196. 



Caiilina flexilis Willd. Abh. Akad. Berlin, 95. 1803. 

 Naias flexilis Rost. & Schmidt, Fl. Sed. 384. 1824. 



Stems branching, slender, 1-2 m. long, or 

 sometimes shorter. Leaves linear. 15-25 mm. 

 long, 1-2 mm. wide, acuminate or abruptly 

 acute, pellucid, with 20-30 minute teeth on each 

 margin, numerous and crowded on the upper 

 parts of the branches ; sheaths obliquely 

 rounded, with 5-10 teeth on each margin; 

 flowers monoecious ; staminate flower 2.5-3 mm. 

 long, the anther 1-celIed ; pistillate flower 1-2.5 

 mm. long, the stigmas 2-4, usually 3, subulate ; 

 seed ellipsoid, apparently smooth and shining. 

 but under a strong lens reticulate with minute 

 6-sided areolae. 



In ponds and streams nearly throughout North 

 America and Europe. On the Pacific Coast it ranges 

 from British Columbia to southern California, occur- 

 ring in the Boreal and Austral Zones, but not conniion. 

 Type locality: Pennsylvania. 



3. Naias guadalupensis (Spreng.) Morong. 

 Guadaloupe Xaias. Fig. 197. 



Caulinia giiadahipciisis Spreng. Syst. 1: 20. 1825. 

 Naias microdon A. Br. Bot. Zeit. 26: 510. 1868. 

 Naias guadalupensis Morong, Mem. Torrey Club 3: 60. 

 1893. 



Stems slender, branching. Leaves all sub- 

 merged, narrowly linear, 12-25 mm. long, about 

 0.5 mm. wide, acute at the apex, and usually 

 tipped with 1 or 2 spines, marginal teeth 20-40, 

 inconspicuous, often wanting: leaf-sheaths ob- 

 lique or rounded, not auriculate, toothed; flowers 

 monoecious ; staminate flowers 2-3 mm. long, the 

 anthers 4-celled ; pistillate flowers 2-3 mm. long ; 

 fruit crowned with 2 or 3 stigmas and usually 

 with 1 or 2 spiny sterile stigmatic processes ; 

 seeds ellipsoid, dull, reticulate with 4-sided 

 areolae. 



In quiet water, ranging from Pennsylvania to Oregon 

 and southward to Central America. On the Pacific 

 Coast it occurs in Oregon and in the San Francisco 

 Bay region. Type locality: Guadaloupe Island. 



Family 4. ZOSTERACEAE. 



Eel-grass Family 



Submerged marine plants with creeping rootstocks, flattened branching stems 

 and sheathing 2-ranked ribbon-like leaves. Flowers monoecious or dioecious, 

 arranged on a one-sided spadix enclosed in a spathe. Perianth none, but flowers 

 enclosed by a hyaline scale. Staminate flowers a single sessile anther arranged in 

 two rows on the spadix ; pollen of slender filaments. Pistillate flower of a single 

 1 -celled ovary, with 2 carpels and 2 slender stigmas. 



A family of marine plants comprising two genera. 

 Flowers monoecious; ovary and fruit ovoid. 1. Zostera. 



Flowers dioecious; ovary and fruit heart-shaped. 2. Phyllospadix. 



1. ZOSTERA L. Sp. Pi. 968. 1753. 



Marine plants, wholly submerged, with slender rootstocks and branching compressed 

 stems. Leaves 2-ranked, sheathing at the base, the sheaths with inflexed margins. Spadix 

 linear, contained in a spathe. Flowers monoecious, arranged alternately^ in 2 rows on the 

 spadix. Staminate flower merely an anther attached to the spadi.x near its apex. 1 -celled; 

 pollen thread-like. Pistillate flower fixed on its back near the middle. Ovary 1 ; style 

 elongated ; stigmas capillary. IMature carpels flask-like, beaked by the persistent style. Seeds 

 ribbed ; embryo ellipsoidal. 



A genus of about 5 species. The following is the type of the genus. 



