68 PONTEDEKIACEAE. 



1. TRADBSCANTIA [Eupp.] 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. comnitmis. 



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. C. 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. of 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. — ScJiists. 



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. PONTEDERIACEAE. 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 adnata to the perianth- 

 tube. Gynoecium 3-carpellary but sometimes with a 1-celled ovaiy. 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. Zosterblla. 



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



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



1. ZOSTEREIjLA 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 

 4r-ll 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. 



