482 NAIADACE^:. (PONDWEED FAMILY.) 



& ZOSEERA.. SKgfils and anthers alternately sessile in 2 rows on one side of & linear spacUx 



oncleseain* leaf. Stigmas 2. 



* * Flowers perfect. 

 4. BOFPf A. SPlowers naked on a spadix : each of 4 large anther-tells, and 4 wraries which 



are raised MI long stalks in fruit. 

 $. BOZAM06&B9N. flowers and fruit spiked. Sepals, stamens, and sessile ovaries each 4. 



1. NAIAS, L. NAIAD. 



Flowers <&icBcious (or sometimes monoecious), axillary, solitary and sessile ; 

 tfhe sterile <eettsis ting of a single stamen enclosed in a little membranous spathe : 

 ranher 9* /first nearly sessile, the filament at length elongated. Fertile flowers 

 coasieting <dF a single ovary tapering into a short style : stigmas 2-4, awl- 

 .shapefl : 'ovuie erect, anatropous. Fruit a little seed-like nutlet, enclosed in a 

 loose. and separable membranous epicarp. Embryo straight, ihr. radicular end 

 downwartts. Slender branching herbs, growing entirely trader water, with 

 ^opposite .linear leaves, somewhat crowded into whorls, sessile and dilated at the 

 base. iFlewers veiy small, solitary, but often clustered with the branch-leaves 

 (Nai'as, water-nymph ; an ill-chosen name for these insignificant 

 ; from their place of growth.) 



L. 3P* 'fi/'XiliS, Rostk. Leaves membranaccous, spreading, very narrowly 

 "linear, entire, or sparingly very minutely denticulate (under a lens); stigmas 

 usually -'8 4. (N. Canadensis, Michx. Caulinia flexilis, WilldJ) Ponds and 

 .-slow streams ; common. July -Sept. (Eu.) 



5T. 3MIWOR (Caulinia fragilis, Willd.), with the more rigid and recurved frag- 

 ile leaves rather strongly toothed, is not identified in this country. 



. 2KANNICHELLIA, Micheli. HOKKEI> 



Flowers monoecious, sessile, naked, usually both kinds from the same axil : 

 the steiiie consisting of a single stamen, with a slender filament tearing a 2 - 4- 

 cellefi ;anther ; the fertile of 2-5 (usually 4) sessile pistils in the same eup- 

 shapefi involucre, forming obliquely oblong nutlets in fruit, beaked with a short 

 style, which is tipped by an obliquely disk-shaped or somewhat 2-lobed stigma. 

 Seedfeathotropous, suspended, straight. Cotyledon taper, bent and coiled up. 

 Stefider branching herbs, growing under water, with very slender stems, op- 

 posite or alternate long and linear thread-form entire leaves, and sheathing 

 memteranous stipules. (Named in honor of Zannidielli> & Venetian botanist.) 



1. 3E. paliistris, L. Style at least half as long as the fruit, which is flat- 

 tish, somewhat incurved, even, or occasionally more or less toothed OK the back 

 (not wing-margined in our plant), nearly sessile, or, in rar. PEIHJKCULATA, both 

 the duster and the separate fruits evidently pednneled. Ponds and slow 

 streams ; rather rare. July. (Eu.) 



3. ZOSTERA, L. GRASS-WRACK. EEL-GRASS. 



Flowers monoecious ; the two kinds naked and sessile and alternately arranged 

 in two rows on the midrib of one side of a linear leaf-like spadix, which is hid- 

 den IB. a long and sheath-like base of a leaf (spathe) ; the sterile flowers consist- 



