68 PONTEDEKIACEAE. 



1. TRADESCANTIA [Rupp.] L. Plants mostly erect. Leaf -blades usually 

 relatively long and narrow. Cymes in involucres of 1-3 leaf -like bracts. Petals 

 nearly equal. Capsules sessile. 



1. T. virginiana L. Stems 2-4 dm. tall, green: leaf -blades mostly 2-7 dm. 

 long, nearly flat: bracts usually much shorter than the leaves: pedicels 2.5-5.6 

 cm. long, villous: sepals 12-18 mm. long, villous, thin in age: petals blue: cap- 

 sule 5-7 mm. long. Frequent in moist soil, commonly on the banks of 

 streams. Spr. SPIDERWORT. 



2. COMMELINA [Plum.] L. Plants mostly spreading. Leaf -blades rela- 

 tively short. Cymes borne in a specialized folded involucre. Perianth irregular. 

 Corolla blue. Stamens 3 or rarely 2. Capsules hidden in the spathe. Sum. 



DAY-FLOWER. DEW-FLOWER. 



Spathes not united at the base. 1. C. oomrmmis. 



Spathes united at the base. 



Each cavity of the ovary with 2 ovules. 2. C. virginica. 



Ventral cavities of the ovary with 2 ovules ; dorsal cavity 



with 1 ovule. 3. G. hirtella. 



1. C. communis L. Stem or branches 3-10 dm. long: leaf -blades lanceolate or 

 oblong-lanceolate, 4-12 cm. long, acute or acuminate: spathes 2-4 cm. long, 

 mainly about twice as long as wide: capsules 6-7 mm. long. In waste grounds 

 and about gardens ; becoming a nuisance in some places. Nat. o the tropics. 



2. C. virginica L. Stem or branches 3-9 dm. long: leaf -blades lanceolate, 

 sometimes narrowly so, 3-10 cm. long, mostly acuminate : spathes 2-3 cm. long, 

 acuminate: capsules 4-5 mm. long. Lower Susquehanna valley. Frequent, 

 on open banks. Schists. 



3. C. hirtella Vahl. Stem 2-12 dm. tall, simple or sparingly branched: leaf- 

 blades lanceolate or oblong-lanceolate, 10-20 cm. long, often scabrous: spathes 

 usually clustered, triangular or ovate-triangular, 2-2.5 cm. long, acute: capsules 

 7-8 mm. long. Lower Susquehanna valley. In rich mud along the river shore. 



Schists. 



FAMILY 3. PONTEDEEIACEAE. PICKEREL-WEED FAMILY. 



Bog or aquatic herbs with rootstocks. Leaves alternate: blades 

 dilated, narrow, or mere phyllodia. Flowers 1 or several from a bract- 

 like spathe. Calyx and corolla of rather similar partially united members. 

 Androecium of 3-6 stamens : filaments unequally adnate to the perianth- 

 tube. Gynoecium 3-carpellary but sometimes with a 1-celled ovary. Fruit 

 a 1-seeded utricle or a many-seeded capsule. 



Stamens 3 : flowers few : perianth salverform. 



Stamens equal : anthers narrow', erect : leaf-blades narrow. 1. ZOSTERELLA. 



Stamens unequal : anthers broad, versatile : leaf-blades broad. 2. HETERANTHERA. 



Stamens 6 : flowers many : perianth 2-lipped. 3. PONTEDERIA. 



1. ZOSTERELLA Small. Aquatic plants with regularly leafy stems. 

 Spadix 1-flowered. Perianth yellow, regular, the lobes narrow, nearly equal. 

 Stamens 3, equal: anthers narrow, erect. Ovary 3 -celled: style conspicuously 

 swollen under the stigma. Ovules numerous. Capsule many-seeded. 



1. Z. dubia (Jacq.) Small. Stem and branches elongate: leaf -blades mainly 

 4-11 cm. long : perianth-lobes linear, 8-12 mm. long : capsules 4-6 mm. long. 

 Susquehanna and tributaries. Eather rare, in still shallow water. Sum. 

 WATER STAR-GRASS. 



