Lythrum is a genus of 38 species of flowering plants native to the temperate world. Commonly known as loosestrife (a name they share with Lysimachia, which are not closely related), they are among 32 genera of the family Lythraceae.
Description
They are herbaceous annuals or perennials. Typically they have square stems, narrow stalkless leaves, and spikes of star-shaped flowers in shades of purple, pink and white. They are especially associated with boggy areas, river banks and ponds, though in cultivation they often tolerate drier conditions. The species L. salicaria (purple loosestrife) and L. virgatum are found in cultivation.
- Lythrum alatum <small>Pursh</small> – winged lythrum
- Lythrum anceps <small>(Koehne) Makino</small> – misohagi (Japan)
- Lythrum californicum <small>Torr. & A.Gray</small> – California loosestrife
- Lythrum curtissii <small>Fernald</small> – Curtiss' loosestrife
- Lythrum flagellare <small>Shuttlw. ex Chapm.</small> – Florida loosestrife
- Lythrum hyssopifolia <small>L.</small> – hyssop loosestrife, grass-poly
- Lythrum junceum <small>Banks & Sol.</small> – false grass-poly
- Lythrum lineare <small>L.</small> – wand lythrum
- Lythrum maritimum <small>Kunth</small> – pūkāmole (Peru, Hawaii)
- Lythrum ovalifolium <small>Koehne</small> – low loosestrife
- Lythrum paradoxum
- Lythrum portula <small>(L.) D.A.Webb</small> – spatulaleaf loosestrife, water purslane
- Lythrum salicaria <small>L.</small> – purple loosestrife
- Lythrum thymifolia <small>L.</small> – thymeleaf loosestrife
- Lythrum tribracteatum <small>Salzm. ex Spreng.</small> – threebract loosestrife
- Lythrum virgatum <small>L.</small> – European wand loosestrife
- Lythrum wilsonii <small>Hewson</small> – Wilson's loosestrife
Formerly placed here
- Cuphea carthagenensis <small>(Jacq.) J.F.Macbr.</small> (as L. carthagenense <small>Jacq.</small>)
- Cuphea melanium <small>(L.) R.Br. ex Steud.</small> (as L. melanium <small>L.</small>)
- Cuphea parsonsia <small>(L.) R.Br. ex Steud.</small> (as L. parsonsia <small>L.</small>)
- Cuphea racemosa subsp. racemosa (as L. racemosum <small>L.f.</small>)
- Cuphea viscosissima <small>Jacq.</small> (as L. petiolatum <small>L.</small>)
- Pleurophora anomala <small>(A. St.-Hil.) Koehne</small> (as L. anomalum <small>A.St.-Hil.</small>)
- Woodfordia fruticosa <small>(L.) Kurz</small> (as L. fruticosum <small>L.</small>)
Morphology
Some species of Lythrum are heterostylous, such as the tristylous (occurring in three forms) L. salicaria.
Ecology
Lythrum species are used as food plants by the larvae of some Lepidoptera species, including the small emperor moth, the engrailed, the Hebrew character, and the V-pug.
As a noxious weed in the United States
The genus Lythrum is listed as a noxious weed in Michigan, North Carolina, and Wisconsin.
Fossil record
So far the oldest evidence of Lythrum is fossil pollen from the early Campanian, 82–81 Ma of Wyoming.