Northern Prairie Wildlife Research Center
Aquatic and Wetland Vascular Plants of the Northern Great Plains
Lythraceae - The Loosestrife Family
Annual or perennial herbs, sometimes woody at the base. Leaves simple,
entire, opposite or both opposite and alternate or rarely some whorled, sessile
or nearly so, exstipulate. Flowers single or few clustered in leaf axils
or in terminal, bracteate, spikelike inflorescences, subsessile or short-pedicelled,
subtended by a pair of small bracteoles on the pedicels, these sometimes deciduous
with age. Flowers perfect, regular or somewhat irregular, often di- or
trimorphic with respect to stamen and style lengths; calyx tubular, cylindrical
or campanulate to globose, strongly nerved, the calyx lobes 4 or 6, alternating
with longer appendages in the sinuses between the lobes; petals 4 or
6, separate, pink or purple, crumpled, deciduous; stamens numbering as
many as or 2X (rarely to 3X) as many as the petals; stigma capitate,
style simple, slender, ovary superior, free of the calyx tube or cup. Fruit
a many-seeded capsule.
||Flowers 4-merous, axillary; calyx tube campanulate
to globose; plants annual.
||Flowers 6-merous, in terminal, bracteate, spikelike
inflorescences; calyx tube cylindrical; plants perennial.
||Leaves of middle and upper stem attenuate at the
base; flowers solitary in the axils.
||Leaves of middle and upper stem auriculate or cordate
and clasping at the base; flowers (1)3-many in the axils.
30. Lythraceae, the Loosestrife Family
1. Ammannia L. -- Toothcup
2. Lythrum L. -- Loosestrife
- 1. Ammannia auriculata Willd.
- 2. Ammannia coccinea Rottb.
- 3. Ammannia robusta Heer & Regel
3. Rotala L. -- Toothcup
- 1. Lythrum alatum Pursh
- 2. Lythrum salicaria L. -- Purple
- 1. Rotala ramosior (L.) Koehne
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