216 LY I'HKACEJE. AMMANNIA. 



smooth or nearly so: leaves in numerous whorls of 6-8, the filiform or 

 linear segments acute, more or less aculeate-dentate. ^ to one inch long: 

 achene 2 lines long or more, elliptical, somewhat compressed, shortly stipi- 

 tate, with a short spine or tubercle on each side near the base, not mar- 

 gined : style as long as the achenes. Washington to California, the East- 

 ern States and Europe. 



ORDER XXXVI. LYTHRACE^ Lindl. Nat. Syst. ed. 2, 184. 



Herbs, rarely shrubs or trees, with usually 4-sided branches 

 opposite, rarely a ternate, entire leaves without stipules and 

 flowers in the axils or in terminal racemes. Sepals combined 

 into a 4 -7-toothed or lobed catyx ; the lobes valvate or distant 

 in the bud ; the sinuses sometimes produced into accessory 

 lobes or processes. Petals alternate with the proper lobes of 

 the calyx and inserted on its throat, deciduous, sometimes 

 wanting. Stamens inserted into the tube of the calyx below 

 the petals, equal to them in number, or 2-4 times as many, 

 rarely fewer: anthers short, introrse. Ovary enclosed in but 

 free from the. calyx, 2-4-celled, with numerous ovules in 

 each cell ; the placentae in the axis : style filiform, sometimes 

 short or almost none : stigma usually capitate Capsule mem- 

 branaceons, surrounded by the calyx, often one-celled by the 

 obliteration of the partitions, dehiscent either longitudinally or 

 irregularly. Seeds numerous and small, rarely few and large, 

 anatropous, without albumen. Cotelydons flat and foliaceous. 



1. Ammannia. Calyx barely 4-angled, short : stamens 4 or 8 : capsule- 

 globular. 



2. Lythrum. Calyx striate, cylindrical: petals usually 6: stamens 

 as many or twice as many: capsule oblong or cylindrical. 



AMMANNIA Houst. L. Gen. n. 155. 



Herbs with square stems, opposite entire leaves and axillary 

 bracteolate flowers. Calyx more or less carn-panulate, 4-5-toothed 

 or lobed, the sinuses usually expanding into spreading accessory 

 teeth or horns. Petals as many as lobes of the calyx or want- 

 ing. Stamens as many or twice as many as lobes of the calyx: 

 Ovary 2-4-celled: style short or rather long: stigma capitate, cap- 

 sule globose or ovoid, included in the calyx, either bursting trans- 

 versely or opening by valves. Seeds numerous, attached to thick 

 central placentae. 



A. latifolia L. Sp. 115. Stems erect, branching, 6-24 inches high: 

 leaves linear-lanceolate, acute, dilated and obtusely cordate-auriculate at 

 base, closely sessile, 2-8 inches long: flowers 1-5 in each axil, somewhat 

 pedunculate, at least when solitary : calyx 4-angled or pleated, with 4 short 

 lobes^nd as many small spreading horn-like processes : petals 4. caducous ; 

 stamens 4 ; style more than half as long as the capsule : capsule 4-celled. 

 Wet places along the Columbia River and the Eastern States. 



A. humilis Michx. Fl. i, 99. Stems ascending, 2-10 inches high, 

 branching from the base: leaves linear-oblong or lanceolate, obtuse, taper- 

 ing below to a short petiole or sessile : flowers sessile or 2-3 in the lower 

 axils; calyx 4-angled with 4 short lobes and as many small spreading pro- 



