LYTHRACEAE (LOOSESTRIFE FAMILY) 591 



LYTHRACEAE (LOOSESTRIFB FAMILY) 



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

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

 lirarlng 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 reciprocally 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. 

 +- Calyx short, campanulate or globular. 



1. Didiplis. Calyx without appendages. Petals none. Stamens 4. Capsule globular, indehis- 



cent, 2-celled. Small aquatic. 



2. Rotala. Calyx with the sinuses appendaged. Petals and stamens 4. Capsules 4-celled, 



septicidal, with 3-4 valves. 



8. Ammannia. Flowers not trimorphous. Petals generally 4 or none. Stamens 4-8. Capsule 

 globular, 2 4-celled, bursting irregularly. 



4. Decodon. Flowers trimorphous. Petals 5 (rarely 4). Stamens 8-10. Capsules 8-4-valved, 



loculicidal. Leaves often whorled. 



+- + Calyx tubular, cylindrical. 



5. Lythrum. Petals usually 6. Stamens mostly 6 or 12. 



* * Flowers irregular and unsymmetrical, with 6 petals and 11-12 stamens In 2 sets. 



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



I. DIDIPLIS Raf. WATER PURSLANE 



Submersed aquatic (sometimes terrestrial), rooting in the mud, with opposite 

 linear leaves, and very small greenish flowers solitary in their axils. (In the 

 words of Kafinesque "Didiplis means two doubling;" from Sis, twice, and 

 SITTAOOS, double, in reference presumably to the stamens.) 



1. D. diandra (Nutt.) Wood. 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. (Z>. 

 linearis Kaf.) Minn, and Wise, to Tex., e. to N. C. and Fla. 



2. ROTALA L. 



Petals 4 (in ours). Capsule-valves (under a strong lens) transversely and 

 closely striate. (Name a diminutive of rota, a wheel, from the whorled leaves 

 of the original species.) 



1. R. rambsior (L.) Koehne. Leaves tapering at base or into a short petiole, 

 linear-oblanceolate or somewhat spatulate ; flowers solitary (rarely 8) in the 

 axils, sessile ; accessory teeth of calyx as long as the lobes or shorter. (Am- 

 mannia humilis Michx.) Low or wet ground, Mass, to Fla. and Tex., and in 

 the interior from O. to Minn., and southw. (Trop. Am.) 



3. AMMANNIA [Houston] L. 



Flowers small, in 3-many-flowered axillary cymes. Calyx globular or bell- 

 shaped, 4-angled, 4-toothed, usually with a little horn-shaped appendage at each 

 sinus. Petals 4 (purplish), small and deciduous, sometimes wanting. Low 

 and inconspicuous smooth herbs, with opposite narrow leaves. (Named, foi 

 Paul Ammann, a German botanist prior to Linnaeus.) 



