PONDWEED FAMILY 



91 



1. Ruppia maritima L. 

 Ditch-grass. Fig. 192. 



Ruppia maritima L. Sp. PI. 127. 1753. 

 Ruppia curvicarpa A. Nels. Bull. Torrey Club 26: 

 122. 1899. 



Stems branching, 6-10 dm. long, often 

 whitish, the internodes irregular, naked, 2.5-8 

 cm. long. Leaves all submerged, thread-like, 

 0.3 mm. wide or less, 2-10 cm. long, acute or 

 pungent at apex ; stipular sheath, 6-10 mm. 

 long, the free part much shorter or wanting ; 

 flowers on a short peduncle which elongates 

 in anthesis and ultimately coils into a loose 

 spiral ; anthers 2, sessile, early deciduous, 2- 

 celled ; fruit ovoid, equilateral or gibbous and 

 oblique, about 2 mm. long, stipitate ; style 

 short and stout, or finely attenuate, straight 

 or hooked; fruiting pedicels 1.5-3 cm. long. 



Brackish or salt water along the seashore and in 

 the interior regions; widely distributed over the 

 northern hemisphere. On the Pacific Coast it is 

 found from British Columbia to southern California, 

 occurring in both the Boreal and Austral Zones. 



2. Ruppia occidentalis S. Wats. 

 Western Ditch-grass. Fig. 193. 



Ruppia occidentalis S. Wats. Proc. Am. Acad. 25: 



138. 1890. 

 Ruppia lacustris Macoun, Cat. Can. PI. 5: 372. 1890. 



Stems slender, 1 m. long or less, with 

 divaricately ascending branches. Leaves all 

 submerged, filiform, less than 0.3 mm. wide, 

 7-20 cm. long; stipular sheaths 1.5-3 cm. long, 

 the free part as long ; inflorescence and flowers 

 similar to the preceding; fruit pear-shaped, 

 tipped by a straight style; fruiting pedicels 

 less than 2.5 mm. long. 



A comparatively little known species, which has 

 been collected only at Kamloops (type locality;, British 

 Columbia, in Nebraska, and at Lake Chelan, Wash- 

 ington. 



3. ZANNICHELLIA L. Sp. PI. 969. 1753. 



Stems capillary, sparsely branched from a creeping rhizome. Leaves all submerged, 

 filiform but flat, 1-nerved. Staminate and pistillate flowers in the same axil, enclosed in the 

 bud by a hyaline spathe-like envelope ; staminate solitary, with 2-celled anther on a short 

 pedicel-like filament; pistillate 2-5. Ovary flask-shaped, stipulate at base, tapering into a 

 short style with a broad cup-shaped stigma, its margins angled or dentate. Fruit a flattish 

 falcate nutlet, ribbed or sometimes toothed on the liack. (In honor of J. H. Zannichelli 

 1662-1729, Italian physician and botanist.) 



A genus of two or three species of wide distribution. Type species, Zanixichellia palustris L. 



