12 NAIADACEAE. 



1. R. maritima L. Stems 0.5-1 m. long; leaves 4-6 cm. long; 

 sheaths membranous, 6-8 mm. long; peduncles 4-20 cm. long or 

 more in fruit; pedicels 1-3 cm. long at maturity; drupes with a 

 hard shell, 2 mm. long, ovoid, oblique or gibbous at base, pointed 

 with the long style. 



Brackish streams along the coast. June-August. 



3. ZANNICHELLIA L. Horned Pondweed. 



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 en- 

 velope; 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 fiattish falcate nutlet, ribbed or some- 

 times toothed on the back. 



1. Z. palustris L. Stems 3-6 dm. high; leaves 2-6 cm. long; 

 spathe separating from the leaves and fruit at maturity; fruits 

 2-6 in a cluster, 2-4 mm. long, sessile or short pedicelled, some- 

 times the whole cluster peduncled; style persistent, straight or 

 curved, 1-2 mm. long. 



Occasional in marshes and ponds. 



Family 5. NAIADACEAE. Naias Family. 



Slender, branching, submerged aquatics from fibrous 

 roots. Leaves all submerged, opposite or whorl ed, 

 spiny-toothed, sheathing at the base. Flowers mon- 

 oecious or dioecious, axillary, solitary, sessile or pedi- 

 celled. Staminate with a double perianth; the outer 

 entire or 4-toothed at the apex, the inner one hyaline, 

 adhering to the anthers. Stamen 1, sessile or stalked; 

 anthers 1-4-celled, apiculate or 2-lobed at the summit. 

 Pistillate flowers of a single ovary, tapering into a short 

 style; stigmas 2-4, subulate. Fruit a solitary carpel, 

 sessile, ellipsoidal, with a crustaceous pericarp. 



1. NAIAS L. Naias. 

 Characters of the family. 



