Lobelia cardinalis

This striking plant, often used as a centerpiece, is known for its vibrant vertical growth and can be grown both submerged in aquariums or emersed. It is a rooted species that is best placed in the middle ground of an aquarium, where its upright form can create a beautiful focal point. While adaptable to a range of standard freshwater conditions, it presents a moderate challenge, making it a rewarding choice for aquarists with some experience. To flourish, it requires good illumination and a nutrient-rich environment. Because it prefers calm water, it should be planted away from the direct output of filters or powerheads. Its growth is steady but not overly fast, so it won't require constant trimming. As it grows, this plant helps improve water quality by absorbing excess nutrients and contributing to the oxygen levels in the tank, making it both a beautiful and functional addition.

An excellent choice for adding vertical structure and color to the midground of a planted tank, this species is highly valued in aquascaping. Its care level is considered intermediate, primarily due to its requirements for lighting and carbon dioxide. While it can survive in lower-tech setups, its growth will be slow and less compact. For optimal health and appearance, moderate to high lighting is essential to prevent the plant from becoming leggy and to encourage dense foliage. Supplemental CO₂ is highly recommended, as it significantly boosts growth rate and overall vitality. This plant is quite adaptable to water chemistry, tolerating a broad spectrum of pH and hardness levels, making it compatible with a wide variety of tank setups without needing extensive water amendments. It thrives in stable, warm, tropical temperatures. As a rooted plant, it draws significant nutrition from the substrate. Planting it in a specialized aquatic soil or enriching a sand or gravel substrate with root tabs will provide the foundation it needs for robust development. In addition to substrate feeding, it also benefits from a regular dosing of liquid fertilizers to supply essential micro and macronutrients. Its moderate growth speed makes it relatively low-maintenance compared to faster-growing stem plants, and its ability to absorb nitrates and phosphates from the water column contributes positively to the aquarium's ecosystem.

A member of the Campanulaceae family, this species is a flowering herbaceous perennial native to a wide range across the Americas. In its natural habitat, it is commonly found in riparian zones, growing along the banks of streams, rivers, and in marshy areas, which explains its ability to thrive in both emersed and submersed conditions. Its conservation status is listed as Least Concern, indicating a stable and widespread wild population. Morphologically, the plant exhibits different characteristics depending on its environment. When grown submersed, it typically presents as an upright stem with alternately arranged leaves. The leaf shape can vary but is generally simple and ovate-to-lanceolate. When allowed to grow emersed, its structure becomes more rigid, the leaves may darken, and it will eventually produce its characteristic terminal raceme of flowers, a key feature of its reproductive cycle. As a tracheophyte, it possesses a vascular system for transporting water and nutrients, allowing it to reach a considerable height. Its physiology is well-suited to a planted aquarium; it performs photosynthesis at a moderate rate, contributing to dissolved oxygen levels. Its demand for medium levels of CO₂ and nutrients reflects its metabolic processes, which require a consistent supply of carbon and other elements to build biomass. Its root system is fibrous and serves as the primary method for anchorage and nutrient uptake from the substrate, making it a true rooting aquatic plant rather than an epiphyte.

Propagating this plant is a relatively straightforward process with a moderate success rate, making it accessible to most hobbyists. It can reproduce both sexually through seeds when grown emersed, but the most common and practical method in an aquarium setting is asexual propagation via stem cuttings. To begin, select a healthy, tall stem from the parent plant and, using sharp aquascaping scissors, cut the top portion, ensuring the cutting is several inches long and has multiple healthy leaves. After making the cut, strip the leaves from the bottom inch of the new cutting to prevent them from rotting under the substrate. The prepared cutting can then be planted directly into the substrate, leaving ample space around it to ensure it receives adequate light and water flow. For successful propagation, environmental factors are key. The new cuttings will root and grow best under the same conditions as the parent plant: moderate to high lighting, a nutrient-rich substrate, and stable water parameters. The addition of CO₂ will significantly accelerate rooting and the development of new leaves. Once planted, the cuttings may go through a short adaptation period. Providing consistent care during this time is crucial for their establishment. To create a dense, bushy appearance, trimmings can be replanted in a group. Regularly trimming the tops of the parent plants will not only provide material for propagation but also encourage the lower portions to sprout new side shoots, leading to fuller growth.