ARROW-GRASS FAMILY 27 



1. T. palustris L. A slender plant, with short rootstock and slender stolons, 

 2-4 dm. high; leaves shorter than the scape, 1-3 dm. long, sharp-pointed; racemes 

 1-3 dm. long; pedicels slender, capillary, in fruit erect, 5-7 mm. long; stigmas 

 sessile; fruit 6-7 mm. long. In bogs: Greenl. N.Y. -Ind. -N.M. Alaska; 

 Eurasia and S. Am. Plain -Mont. Jl-S. 



2. T. maritima L. A stout plant, with subligneous rootstock, without 

 stolons; leaves half-cylindric, 2 mm. wide; racemes often 4 dm. long or more; 

 pedicels decurrent, 2-3 mm. long, in fruit ascending; fruit 5-6 mm. long, 3-4 

 mm. in diameter; carpels triangular, grooved on the back. In salt marshes: 

 Lab. -N.J. Calif. -Alaska; Eurasia. Plain Submont. Je-S. 



2. SCHEUCHZERIA L. 



Rush-like bog plants, with perennial, creeping rootstock. Leaves half-round 

 below, flat above, striate, and with membranous sheaths at the base. Perianth 

 with 6 segments in two series. Stamens 6; filaments elongated; anthers linear, 

 basifixed. Ovaries 3, rarely 4-6, distinct or connate at the base, 1-celled, each 

 cell with 1-2 ovules. Fruit of 3-6 divergent follicles, opening on the inside. 



1. S. palustris L. A leafy bog plant, 1-2.5 dm. high; leaves 1-4 dm. long, 

 the upper reduced to bracts; basal leaves with sheaths often 1 dm. long and 

 ligules 1 cm. long; pedicels 6-20 mm. long, in fruit spreading; flowers white; 

 segments 1 -nerved, 3 mm. long; follicles 5-6 mm. long. In bogs: Lab. -N.J. 

 Wise. Calif. 'Alaska; Eurasia. Boreal-Submont. Je-Jl. 



Family 10. ALISMACEAE. WATER-PLANTAIN FAMILY. 



Marsh or aquatic plants, with scapose stems, basal long-petioled sheath- 

 ing, mostly cross-veined, leaves, and fibrous roots. Flowers mostly verticil- 

 late, in elongated racemes or panicles, regular, pedicelled. Sepals 3, per- 

 sistent. Petals 3, deciduous. Stamens 6 or more, included. Pistils many, 

 distinct: ovaries 1-celled and generally 1-ovuled, becoming achenes in fruit. 



Carpels in a ring on a, small flat receptacle; flowers perfect. 1. ALISMA. 



Carpels in several series on a convex receptacle; flowers monoecious or dioecious. 



2. SAGITTARIA.. 



1. ALISMA L. WATER-PLANTAIN. 



Annual or mostly perennial scapose herbs. Leaves erect or floating; blades 

 several-veined, petioled. Flowers perfect in compound panicles. Sepals 3, usually 

 ribbed, persistent. Petals 3, white or pinkish, spreading, deciduous. Stamens 

 6, two opposite each petal. Carpels few or many, in one whorl. Achenes 

 ribbed or grooved on the back. 



Achenes longer than wide, grooved on the back, their inner edges not meeting; pedicels 



straight, ascending. 1. A. brevipes. 



Achenes as wide as long, ribbed on the back, their inner edges meeting; pedicels recurved. 



2. A. Geyeri. 



1. A. brevipes Greene. Perennial; leaf -blades oblong to ovate, 5-19 cm. 

 long, acute at the apex, rounded, truncate or subcordate at the base; scape 1 m. 

 higher less: sepals orbicular or rounded-ovate, 3 mm. long or more; petals 5-6 mm. 

 long; fruiting heads 5-6.5 mm. broad; achenes broadly obovate, 2.5-3 mm. 

 long; beak ascending. A. superba Lunell. In water and wet places: N.S. N.D. 

 N.M. Calif. B.C. PlainMont. 



2. A. Geyeri Torr. Perennial; leaf-blades oblong to ovate-lanceolate, 

 rarely lance-linear, 5-9 cm. long, acute at both ends; scapes mostly 1-5 dm. 

 long, diffusely spreading; sepals rounded-ovate, about 2-5 mm. long; petals 2-4 

 mm. long; fruiting heads 4.5-5.5 mm. broad; achenes suborbicular; beaks erect. 

 Wet places: w N.Y. -N.D. -Nev. 'Ore. Plain Submont. 



2. SAGITTARIA L. ARROW-HEAD, SWAN OR SWAMP POTATO. 



Perennial water or bog plants, with tuber-bearing or nodose rootstocks. 

 Leaves long-petioled, with a sagittate or lanceolate blade or, especially the earlier 

 ones, reduced to bladeless phylloids. Flowers monoecious or dioecious, borne 



