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 tha^ i. — (Gk. poiamos 

 - 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 



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



Naias (water nymph) 



BB. Leaves terete, 1-4.S 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.) 



Phyllospadiz (sea basket-grass) 



JUNCAGINACEAE (Arrow-grass Family) 



Perennial marsh Jierbs. 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 foUicle. 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 spikeUke 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 



