''Justicia americana'', the American water-willow, is a
herbaceous
Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials.
Definitions of "herb" and "herbaceous"
The fourth edition ...
,
aquatic flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of ...
in the family
Acanthaceae
Acanthaceae is a family (the acanthus family) of dicotyledonous flowering plants containing almost 250 genera and about 2500 species. Most are tropical herbs, shrubs, or twining vines; some are epiphytes. Only a few species are distributed in ...
native to
North America. It is the hardiest species in the genus ''
Justicia'', the other members of which being largely
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
and
subtropical, and it is able to survive as far north as
USDA zone
A hardiness zone is a geographic area defined as having a certain average annual minimum temperature, a factor relevant to the survival of many plants. In some systems other statistics are included in the calculations. The original and most wide ...
4. It is common throughout its range.
The grows partially submerged in still or flowing water, reaching up to tall from a creeping
rhizome. The
leaves are , opposite, sessile, linear or lanceolate, and slightly crenulated. The flowers are bicolored, borne in opposite arrangement on
spikes
The SPIKES protocol is a method used in clinical medicine to break bad news to patients and families. As receiving bad news can cause distress and anxiety, clinicians need to deliver the news carefully. By using the SPIKES method for introducing a ...
long coming off a
peduncle Peduncle may refer to:
*Peduncle (botany), a stalk supporting an inflorescence, which is the part of the shoot of seed plants where flowers are formed
*Peduncle (anatomy), a stem, through which a mass of tissue is attached to a body
**Peduncle (art ...
long. Color ranges from white to pale lavender with the upper corolla lip pale violet or white, arching over the lower lip mottled in dark purple. The lateral
lobes are unadorned or slightly blushed. The
anthers are purplish-red rather than the usual yellow. Flowering is from May to October. The fruit of this plant is a small brown capsule.
The creeping rhizome allows ''Justicia americana'' to form large colonies on or near the shorelines of still or slow waters in lakes and rivers, and on rocky riffles and shoals in faster flowing rivers. Its rhizomes and roots provide important spawning sites for many fish species and habitat for invertebrates.
''Justicia americana''
Native Plant database at wildflower.org
References
americana
Flora of the United States
Freshwater plants
Plants described in 1753
Taxa named by Carl Linnaeus
{{Acanthaceae-stub