JUNCAGINACEAE (ARROW-GRASS FAMILY) 35 



DD. Often with some wide leaves, often the upper leaves opposite; stamens 4; 



fruit sessile. (See F.) 



CC. Leaves opposite or in whorls of 3, all linear, 8-25 mm. long; pistils more 

 than i. 



E. Leaves not spiny; pistils 2-10. 



F. Flowers perfect, in spikes or clusters; stamens more than i. (Gk. potamos 

 = a river, geiton = a neighbor; from the habitat.) 



Potamogeton (PONDWEED) 



FF. Flowers monoecious, axillary; stamen i. E. (Honor of G. G. Zanni- 

 chelli, a botanist of Venice.) Zannichellia palustris (HORNED PONDWEED) 

 EE. Leaves spiny on the margins or back or both; flowers solitary in the leaf 

 axils; pistil i. (Gk. naias = a water nymph; from the habitat.) 



Naias (WATER NYMPH) 



BB. Leaves terete, 1-4.5 mm. in diameter, all basal; stem not elongated. W. 

 (Meaning not determined.) Lilaea subulata 



AA. Growing along tide-water shores from i m. above low tide to 2 m. below it ; not 

 in salt marshes. 



G. Plants growing on muddy bottom; leaves 3-15 mm. wide. W. (Gk. zoster 

 = a belt; referring to the leaves.) Zostera marina (EEL-GRASS) 



GG. Plants growing mostly in rock crevices; leaves 4 mm. or less wide. (Gk. 

 phyllon = a leaf; + spadix; inflorescence inclosed in leaf base.) 



Phyllospadix (SEA BASKET-GRASS) 



JUNCAGINACEAE (ARROW-GRASS FAMILY) 



Perennial marsh herbs. Leaves rushlike; blades terete or half 

 terete at least near their base. Flowers perfect, in spikes or 

 racemes. Perianth 3~6-parted, in 2 .very similar series. Stamens 

 3-6, on the base of the perianth. Carpels 3-6, more or less 

 united until maturity. Fruit a capsule or follicle. Seeds 1-2 

 in each carpel. Difficult family. Key mostly only to genera. 

 (F. & R. p. 34-) 



A. Leaves all basal; flowers many, bractless, in a spike or spikelike raceme; 

 anthers oval; stigmas plumose. (Gk. treis = 3, glochis = point; some species 

 have 3-pointed fruits.) Triglochin (ARROW GRASS) 



AA. Stem leafy; flowers few, bracted, in loose racemes; anthers linear; stigmas 

 papillose or slightly fimbriate. W. C. E. (Honor of J. and J. J. Scheuchzer, 

 Swiss botanists.) Scheuchzeria palustris 



ALISMACEAE (WATER-PLANTAIN FAMILY) 



Aquatic or marsh herbs, annual or perennial. Leaves basal; 

 petiole long, sheathing at base; blade flat, several-ribbed, often 

 with spreading or deflexed lobes. Scapes erect or floating. Flowers 

 perfect or unisexual, regular, whorled, borne in terminal racemes 

 or panicles. Calyx of 3 persistent green sepals. Corolla white 



