LYTHRACEAE 825 



13. Rhexia aristosa Britton. Stems erect, 2-6 dm. tall, 4-angled, glabrous, some- 

 times branching above, sometimes spongy at the base, the branches erect or strongly ascend- 

 ing : leaf -blades thickish, linear or linear-lanceolate, or sometimes linear-oblong, 1-3 cm. 

 long, obtusish or acute at the apex, distantly bristly serrulate, sessile, glabrous or with a 

 few scattered hairs above : flowers short-pedicelled : hypanthium bristly, or the tube gla- 

 brate in age : sepals linear or linear-lanceolate, acuminate : petals magenta- red, 12-20 mm. 

 long, awn-tipped : anthers linear, minutely spurred : capsules subglobose, 6 mm. long, longer 

 than the neck of the hypanthium. 



In sandy swamps and pine lands, New Jersey to South Carolina. Summer. 



14. Rhexia parviflora Chapm. Stems erect, less than 3 dm. tall, 4-angled, usually 

 branched at the base and above, sparingly pubescent : leaf-blades oblong, elliptic or nearly 

 oval, 1-2 cm. long, acute, bristly serrulate, short-petioled : cymes few-flowered : hypan- 

 thium nearly glabrous at maturity : petals white, less than 10 mm. long, often .awn-tipped : 

 anthers narrow, nearly straight, appendaged, fully as long as the filaments : capsules sub- 

 globose, about 3 mm. in diameter : mature hypanthium with a broad neck much shorter 

 than the diameter of the body. 



In shallow ponds, Apalachicola, Florida. Summer. 



FAMILY 2. LYTHRACEAE Lindl. LOOSESTRIFE FAMILY. 



Herbs, shrubs, or often trees in the tropics, with firm or succulent tissues. 

 Leaves mostly opposite : blades usually entire, sometimes auricled at the base. 

 Flowers perfect, solitary or clustered in the axils, or in axillary cymes. Hypan- 

 thium enclosing the ovary, but free. Calyx of 4-5 sepals, commonly accom- 

 panied by accessory teeth. Corolla of 4-5 petals, or wanting. Androecium of 

 few or many stamens in 1 or several series. Filaments mostly filiform : anthers 

 versatile. Gynoecium compound. Ovary 2-6-celled, or rarely 1-celled. Styles 

 united. Stigmas entire or rarely 2-lobed. Ovules numerous, or rarely few, 

 anatropous. Fruit a thin-walled or firm capsule enclosed in the hypanthium, 

 sometimes indehiscent. Seeds variously marked or roughened. Embryo 

 straight. 

 Hypanthium campanulate or turbinate, becoming hemispheric or globose. 



Flowers inconspicuous. 



Petals wanting : capsules indehiscent. 1. DIDIPLIS. 

 Petals 4 : capsules dehiscent, sometimes irregularly so. 



Capsules bursting irregularly. 2. AMMANNIA. 



Capsules septicidally dehiscent. 3. ROTALA. 



Flowers conspicuous. 4. HEIMIA. 

 Shrubs or trees. 



Flowers in axillary cymes : aquatic shrubs. 5. DECODON. 



Flowers in terminal panicles : terrestrial shrubs or trees. 6. LAGERSTROEMIA. 

 Hypanthium elongated, cylindric or tubular. 



Flowers regular : hypanthium symmetrical. 7. LYTHRUM. 



Flowers irregular : hypanthium oblique. 8. PABSONSIA. 



1. DIDIPLIS Kaf. 



Flaccid aquatic or swamp herbs, resembling species of Callitriche. Stems elongated, 

 4-angled. Leaves opposite : blades narrow, entire, pellucid. Flowers inconspicuous, ses- 

 sile and solitary in the axils. Hypanthium prismatic-campanulate, 4-angled. Sepals 4, 

 without accessory teeth. Petals none. Stamens 2-4, mostly 4 : filaments very short. 

 Ovary 2-celled : style very short : stigma slightly 2-lobed. Capsule subglobose, 2-celled, 

 opening irregularly. Seeds minute. Testa membranous. Embryo clavate. 



1. Didiplis diandra (Nutt.) Wood. Stems flaccid, submerged or creeping on mud, 

 1-3 dm. long, glabrous : leaves of two kinds, the submersed thin ; blades linear to linear- 

 lanceolate, acute or acuminate, the emersed ones thicker in texture ; blades linear to linear- 

 spatulate, often obtuse, all 1-2 cm. long : flowers inconspicuous : hypanthium campanu- 

 late, angled, about 1 mm. high : petals none : capsule urn-shaped, about 1 mm. in diameter. 

 ID. linearis Raf . ] 



In ponds or on wet shores, Minnesota to North Carolina, Florida, Texas and Mexico. Spring to 

 fall. WATER PURSLANE. 



2. AMMANNIA L. 



Annual, leathery -succulent herbs. Stems usually 4-angled. Leaves opposite : blades 

 entire, often auricled at the base. Flowers inconspicuous, solitary or clustered (cymose) in 



