Common Names in English: Annual, Purple Ammannia, Scarlet
Toothcup, Scarlet Ammannia, Scarlet Loosestrife, Toothcup,
Valley Redstem , or trees ; young stems often quadrangular .
Leaves opposite, often decussate, or whorled , rarely
subalternate to alternate, simple , entire; pinnately veined,
secondary veins typically joined in a series of intramarginal
arches; stipules vestigial or absent. Inflorescences racemes ,
cymes, or panicles; flowers axillary , usually 4-, 6- or
8-merous, sometimes 3- or 5-merous, bisexual , regular or
irregular. Floral tube perigynous, hemi-epigynous, or epigynous
in fruit, membranous to leathery, often 6-12-ribbed; sepals
valvate , equal to much shorter than floral tube, membranous to
thickly leathery, persistent; epicalyx alternating with sepals
or absent. Petals inserted of floral tube, alternating with
sepals, crinkled , clawed or not, frequently caducous , rarely
absent. Stamens usually biseriate and 2 Ã— as many as sepals,
sometimes uniseriate , inserted near base of floral tu