184 LYTHRACE.E. (LOOSESTRIFE FAMILY.) 



ORDER 41. LYTHRACEvE. (LOOSESTRIFE FAMILY.) 



Herbs, with mostly opposite entire leaves, no stipules, the calyx enclosing 

 but free from the 1 -4-celled many-seeded ovary and membranous capsule, 

 and bearing the 4-7 deciduous petals and 4-14 stamens on its throat ; the 

 latter lower down. Style 1 ; stigma capitate, or rarely 2-lobed. Flowers 

 axillary or whorled, rarely irregular, perfect, sometimes dimorphous or 

 even trimorphous, those on different plants with filaments and style re- 

 ciprocally longer and shorter. Petals sometimes wanting. Capsule often 

 1-celled by the early breaking away of the thin partitions ; placentae in the 

 axis. Seeds anatropous, without albumen. Branches usually 4-sided. 



* Flowers regular or nearly so. 

 - Flowers mostly solitary in the axils of the leaves, sessile or nearly so. 



1. Didiplis. Calyx short, without appendages. Petals none. Stamens 4. Capsule inde- 



hisi'ent. Small aquatic. 



2. Rotala. Calyx short, the sinuses appendaged. Petals and stamens 4. Capsule septi- 



cidal, with 3-4 valves. 



3 Ammannia. Flowers not trimorphous. Petals generally 4 or none. Stamens 4. Cap- 

 sule bursting irregularly. 



*- *- Flowers in 3 - many-flowered axillary cymes (rarely solitary). 



4. Lijrthrum. Calyx tubular. Petals usually 6. Stamens mostly G or 12. Flowers 



cymose-spicate in one species. 



5. Decodon. Flowers trimorphous. Petals 5 (rarely 4). Stamens 8-10. Capsule 3-4- 



valved, loculicidal. 



* * Flowers irregular and unsymmetrical, with 6 petals and 11 stamens. 



6. Cupliea. Calyx spurred or enlarged on one side at base. Petals unequal. 



1. DIDIPLIS, Eaf. WATER PURSLANE. 



Calyx- short-campanulate or semiglobose, with no appendages at the sinuses 

 (or a mere callous point). Petals none. Stamens 4, short. Capsule globular, 

 indehiscent, 2-celled. Submersed aquatic (sometimes terrestrial), rooting in 

 the mud, with opposite linear leaves, and very small greenish flowers solitary 

 in their axils. (" Didiplis means two doubling ; " from Sis, twice, and 5nr\6os, 

 double.) 



1. D. line&ris, Raf. Leaves when submersed elongated, thin, closely 

 sessile by a broad base, when emersed shorter and contracted at base ; calyx 

 with broad triangular lobes ; style very short ; capsules very small. (Amman- 

 nia Nuttallii, Gray.) From Minn, and Wise, to Tex., east to N. C. and Fla. 



2. ROTALA, L. 



Calyx short-campanulate or semiglobose, with tooth-like appendages at the 

 sinuses (abnormally, iu our species). Petals 4 (in ours). Stamens 4, short. 

 Capsule globular, 4-celled, septicidal, the valves (under a strong lens) trans- 

 versely and densely striate. (Name a diminutive of rota, a wheel, from the 

 whorled leaves of the original species.) 



1. R. ramosior, Koehne. Leaves tapering at base or into a short petiole, 

 linear-oblanceolate or somewhat spatulate; flowers solitary (rarely 3) in the 

 axils and sessile ; accessory teeth of calyx as long as the lobes or shorter. 



