438 NAIADAOE^E. [ZANNICHELLIA. 



Sub-sp. Z. POLYCAR'PA, Nolte ; drupelets often 5-6 subsessile, back cylindric, 

 .style - as long, stigma large repanded, filament T 3 o-| in., auther 2-celled. 

 VAB. tennis' sima, Fr. ; very slender. 



6. ZOSTE'RA, L. GRASSWRACK. 



Grass-like marine plants ; rootstocks matted, creeping. Stem com- 

 pressed. Leaves distichous, sheathing, long, linear ; stipules adherent to 

 the sheathing leaf-base. Flowers in 2 parallel series of alternating anthers 

 and carpels on one surface of a linear membranous peduncled spadix, which 

 is enclosed in a sheathing leaf-like spathe. Perianth 0. Anthers sessile, 

 ] -celled, dehiscence longitudinal ; pollen of slender tubes. Carpels ovoid, 

 fixed laterally ; style subulate persistent, stigmas 2 capillary exserted from 

 the spathe, deciduous; ovule pendulous, orthotropous. Utricle dehiscent. 

 Seed ovoid, testa tough ; embryo large, oblong, deeply grooved, cotylc- 

 donary end sigmoid, slender, sunk in the groove, plumule immersed. 

 DISTRIB. Various coasts ; species 4. ETYM. fatrTJip, a riband. 



1. Z. mari'na, L. ; spathe dilated above the peduncle, its blade long, 

 spadix many-fld. margin entire. 



Muddy and sandy estuaries near low-water mark, N. to Shetland ; Ireland ; 

 Channel Islands; fl. July-Sept. Rootstock slender, rather fleshy. Leave* 

 1-3 ft., j-J in. broad, obtuse, bright green, opaque, 1-7-iierved. Spathe, 

 including the leafy portion, 6-10 in., varying in breadth as the foliage does. 

 Spadix 1-3 in. Flowers green, usually in series of 2 anthers (perhaps one 

 2-celled anther) and an ovary. Fruit J in. furrowed. DISTRIB. Most temp, 

 coasts (Arctic). 



VAB. mari'na proper; leaves j-J in. broad 3-7 -ribbed. VAR. anyustifo'lia , 

 Syme ; leaves ^-j in. broad 1-3-nerved. Orkney, &c. 



2. Z. na'na, Roth ; spathe dilated above the peduncle, its blade short, 

 spadix few-fld. , margin with inflexed membranous appendages. 

 Estuaries, rare, from Forfar and Argyll to Sussex and Cornwall ; Dublin Bay ; 



fl. July-Sept. Similar to Z. mari'na, var. angustifo'lia, but leaves not more 

 than 6 in. by J- broad ; fruit shorter and very obscurely striate. DISTRIB. 

 Atlantic coast of Europe, N. Africa. 



7. NA'IAS, L. 



Very slender, submerged, fresh-water herbs. Leaves linear, opposite 

 fascicled or whorled ; stipules adnate to the leaf-base. Flowers 1-sexual, 

 solitary or crowded. MALE. A solitary 1-4-celled anther enclosed in 2 

 sheaths, the outer sheath toothed ; pollen large, globose. FEMALE. A soli- 

 tary sessile carpel, naked or enclosed in sheaths ; style short, stigmas 2-4 

 persistent subulate ; ovule basal, erect, anatropous. Drupe small ; epi- 

 carp thin, separable. Seed ovoid, testa thin ; embryo straight, oblong, 

 radicular end largest. DISTRIB. Various climates ; species 10. ETYM. 

 ?a?av, a water-nympli . 



