Justicia americana, the American water-willow, is a herbaceous, aquatic flowering plant in the family Acanthaceae native to North America. It is the hardiest species in the genus Justicia, the other members of which being largely tropical and subtropical, and it is able to survive as far north as USDA zone 4. It is common throughout its range. The grows partially submerged in still or flowing water, reaching up to 40 cm (16 in) tall from a creeping rhizome. The leaves are 10 cm (3.9 in), opposite, sessile, linear or lanceolate, and slightly crenulated. The flowers are bicolored, born in opposite arrangement on spikes 3 cm (1.2 in) long coming off a peduncle 10 cm (3.9 in) 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.
American water-willow is fairly resistant to disease and typically not vulnerable to illnesses. Still, it can be affected by pests and diseases present in its environment. Such infections are generally mild. Carewise, this plant needs a moderate level of attention. It should be pruned regularly to preserve an attractive appearance and healthy growth. Applying fertilizer can also encourage blooming. American water-willow is appropriate for anyone who has outdoor space, like a garden or patio, and does not demand extensive care experience. If kept indoors, it may need more attentive care.
How to keep Dianthera Americana.
Light
American water-willow grows best with a full spectrum of light but can withstand partly shaded conditions. Its natural habitat reflects this preference. Too little light can restrict its growth, while too much exposure may be harmful, emphasizing its need for balanced lighting conditions.
Temperature
American water-willow occurs naturally in habitats where temperatures range from 32 to 95 °F (0 to 35 ℃). It thrives in the gentle climates common to many temperate zones. When seasonal conditions become extreme, appropriate climatic adjustments should be implemented to mirror its native environment.
Botanical profile.
- Plant Type
- Herb
- Life Cycle
- Perennial
- Genus
- Dianthera
- Family
- Acanthaceae
- Hardiness Zone
- 3-10
- Mature Height
- 30 cm to 91 cm
- Mature Spread
- 61 cm
- Leaf Color
- Green, Dark Green
- Leaf Type
- Deciduous
- Flower Color
- Lavender, Purple
- Flower Size
- 2.54 cm
- Bloom Time
- Late spring, Early summer, Mid summer
- Planting Time
- Spring
- Harvest Time
- Mid summer, Late summer, Early fall
- Native Area
- Mexico, Canada
Other names.
