Subclass Liliidae ( Liliidae )
Order Asparagales ( Asparagales )
Family Amaryllidaceae ( Amaryllidaceae )
Genus Crinum — Crinum.
Regardless of their habitat, all Crinum species share a number of common features. These include long ribbon-like leaves in aquatic species or lanceolate leaves in terrestrial species with dense outer layers that release large amounts of alkaloid-rich mucus when damaged. They also feature fairly large flowers—ranging from white and yellow to intense pink and purple—gathered in an umbel inflorescence on a stalk up to a meter long. Depending on the species, the inflorescence can contain from 2 to 50 long-tubular flowers with 6 petals and a bunch of 6 long stamens with large anthers (sometimes brightly colored) and a single pistil.
All Crinum species have multi-scaled bulbs. The roots are powerful, poorly branched, succulent, ranging from white to brown depending on the substrate and growing conditions. All species are undemanding and long-lived, although they are only suitable for large and tall aquariums. They thrive in tanks over a meter deep, provided there is sufficient lighting. Due to the abundant mucus containing alkaloids, Crinums are practically undamaged by fish, even herbivorous ones. The powerful root system securely anchors the plant in the substrate, making it possible to keep burrowing fish with them—these features expand their potential use in the design of challenging aquariums.
Curly Crinum, wavy crinum — Crinum calamistratum.
"1" Synonym: Crinum natans “Crispus”. (English – African Onion Plant, Cameroon Crinum). West Africa, rivers of western Cameroon. Height 40-120 cm. Width 20-30 cm. Forms an attractive rosette with dark green, very narrow, twisted leaves up to 1 meter long and no more than 0.7 cm wide; they are rigid and brittle with wavy margins. The leaves consist of a strong central vein and narrow, strongly wavy lateral parts of the leaf blade. An adult bush can have up to 40 leaves, although usually fewer. The bulb is poorly developed, up to 3 cm in diameter. Requires more light. A well-growing plant produces a large number of small bulbs.
"2" Temperature 20-28°C. Soft to medium-hard water with pH 7, dH 2-15° is recommended. It is desirable to enrich the water with CO2. Medium-intensity lighting is sufficient. Strong water circulation promotes plant growth.
"4" The root of Crinum is bulb-shaped, about 3 cm thick, and can reach up to ten centimeters in length. The powerful but fragile roots of these plants strongly dislike transplantation and are prone to rotting. Any damage to the roots halts plant growth. When planting, make sure that only the very base of the bulb is buried in the substrate.
Prefers a loose, fine-grained, humus-rich substrate at least 8 cm deep. The substrate should contain nutrients; it is recommended to place a few clay balls under the bulbs. The slightest overdose of fertilizers can disrupt the biological equilibrium in the aquarium and trigger a massive algae bloom, which heavily damages Crinum leaves and causes them to die off.
"5" The plant is intended for maintenance in a tall aquarium with a minimum height of 50 cm. Planted in the middle or background of spacious aquariums. The plant should be planted separately from other plants. In fact, planting should be approached with full responsibility because the plant dislikes transplantation very much and grows poorly if disturbed periodically. Not eaten by herbivorous fishes. Can be used in brackish aquariums with low salt concentrations. Grows extremely slowly; it can take half a year before the plant grows and takes on a more or less impressive appearance.
"6" Propagated by daughter bulbs; sometimes a strong bush bears up to 20 offsets of various ages. An adult bush produces offsets inside the maternal bulb or right next to it. Offsets grow slowly, especially if there are many of them, and they should only be separated after forming 5-7 leaves and at least 2-3 roots. Later they can be planted in the substrate, burying them to 2/3 of their size.
Floating Crinum — Crinum natans.
"1" Inhabits rivers in West Africa from Guinea to Cameroon and south to the Congo. Under favorable conditions, the plant can reach a height of 50-120 cm. Width 20-30 cm. This is a long, moderate green plant with corrugated leaves. A strong adult specimen can bear up to 20-25 leaves. The stem is thick and short. Forms a decorative rosette of long, narrow, broadly ribbon-shaped, downward-curved, dark green leaves with a corrugated surface. The leaf edges are smoothly wavy, and the apex is gradually pointed. Leaf length up to 1.5 m, width 1.5-5 cm. The main vein is light, occupies up to a third of the leaf width, and strongly protrudes from the underside of the leaf.
The leaf width and the shape of its margin can vary significantly among different plants. Young leaves have a brown coloration, but turn green as the plant matures. There are a number of forms of this species that differ in leaf characteristics. There are narrow-leaved and wide-leaved forms, and some smoothly twisted along the central vein. Perhaps the most decorative is Crinum natans f. “Torta”, in which the lateral parts of the leaf blade are frequently and finely corrugated, as if compressed along the central vein.
"2" Temperature 20-28°C. Develops well in soft to medium-hard water with pH in the neutral range. pH 6.0-7.4, dH up to 12°. Medium-intensity lighting is sufficient. Under intense lighting, young leaves are brownish but eventually turn green. Daylight duration should be at least 12 hours. Water enriched with CO2 promotes better plant development. The aquarium must have enhanced water circulation, as in nature it grows in fast-flowing rivers.
"4" The plant is very powerful with a large bulb-like rhizome, the size of which reaches up to 5 cm. The bulb appears only as a thickening at the base of the leaf rosette up to 4.5 cm in diameter, resembling a real onion. Adventitious roots go deep into the substrate. The rhizome has a single growth point, so it does not produce shoots. Handling the roots requires the most attention when growing Crinums.
The powerful but fragile roots of these plants strongly dislike transplantation and are prone to rotting. Any damage to the roots halts plant growth, so be patient when planting the plant in your aquarium. Before it starts growing, the plant must restore its root system, and this takes time. According to the size of the bulb, the substrate should be at least 10 cm deep, coarse, and nutritious. Sand and fine gravel can be used as substrate.
"5" This is truly a very beautiful plant, but given its large size, keeping a floating Crinum requires a very large aquarium. Suitable for indoor water bodies and not eaten by herbivorous fishes. The tough foliage ensures the plant’s survival even in aquariums with vegetarian fish. The plant is intended for maintenance in aquariums with a minimum height of 50 cm so that the ribbon-like leaves can spread across the water surface.
Planted in the background, separately from other plants. Since the plants prefer places with a fast current, you should ensure good water circulation in the aquarium. Transplantation has a negative effect on Crinum. Only one leaf grows per month. Leaves sprawling across the water surface create dense shade and can hinder the normal development of other aquarium flora, so they need to be trimmed periodically.
"6" Buds of future daughter plants form along the circumference of the rhizome, covered by bulb scale leaves. The shoot develops under this reliable shield, moves upward behind this wall, and its leaves emerge in the axils of old large leaves 5-8 cm above the level where it actually formed. Removing the protective scales and exposing the bud stops its growth. Gaining strength, the shoot gradually pushes apart the bulb scales and old leaves, and after a few months, its lower part is exposed. Over time, the offset’s small bulb moves away from the maternal bulb on a thick white root structure and independently roots in the substrate. When propagating the plant, the daughter plant is often forcibly separated when it grows 5 leaves.
Thai Crinum — Crinum thaianum.
"1" (English – Onion Plant). Inhabits rivers of southern Thailand. Reaches a size of 50 to 100 cm. Bush width 20-25 cm. A hardy, undemanding, and resilient plant. Moreover, it is extremely unpretentious regarding lighting levels and water composition. Leaves range from light green to dark green with straight edges and a slightly convex narrow midrib, up to 2 meters long and 1.5-2.5 cm wide. The leaf apex is shortly pointed. However, they are very strong and elastic. They can be trimmed and tied into a knot, and most aquarium fish cannot damage them. A strong adult bush can bear up to 15 leaves. They can be straight like those of giant Vallisneria, twisted in a loose spiral around the central vein, or corkscrew-shaped. Spreading like a serpentin across the water surface, they can cover the entire surface of the aquarium, shading other plants.
"2" Crinum should be grown in a tropical water body at a water temperature not lower than 22°C. In colder and slightly acidic water, growth slows down significantly, and the plant begins to shed old leaves. The water can be soft to medium-hard. Keep in mind that if the water hardness is below 4°, Crinum will stop growing steadily. dH not lower than 4°, pH 7.0-8.0. The water must be clean, and a fourth of it must be replaced weekly. Lighting can be moderate to strong. The long leaves of Crinum rise to the surface and are located in close proximity to the light fixture, so the plant receives enough light even from a relatively weak light fixture. Lighting for at least 12 hours.
"4" The bulb is rounded, up to 7 cm in diameter in old specimens, much thicker than the light elongated base of the leaf rosette. Thanks to the bulb, this plant always has a nutrient reserve for unfavorable periods of its life. Sand or fine gravel can be used as substrate. The substrate must contain a large amount of organic matter. When planting in a new substrate, it is advisable to place a lump of clay or a mixture of clay and peat under Crinum’s roots. Over time, as a result of natural silting of the substrate, the plant will have enough organic matter. The substrate layer thickness when planting a young plant should be about 5 cm; as the plant develops, substrate can be added, increasing the layer to 7-10 cm.
"5" This is a very beautiful and strong plant for a tall aquarium. Crinum can only be kept in a large tank. Suitable for indoor water bodies. It is usually placed near the back or side walls of the aquarium. Crinum must be planted in the substrate (or in a pot with substrate). Do not bury the bulb. The bulbs should protrude from the substrate by 2/3, otherwise the bulb may rot. Due to its rapid growth, dense thickets of long floating leaves will cover the water surface in a short time. The leaves spread across the entire surface of the aquarium like a serpentine, thereby shading other plants. Overly long leaves of this plant can be carefully trimmed. But be careful not to damage the bulb itself when trimming the leaves.
"6" Propagated vegetatively by bulbs. The plant forms daughter bulbs located close to the maternal plant. The first offsets appear only 3-5 years after planting, so quite a long time may pass before propagation occurs. Propagation via bulbs is achieved more often in old plants than in Crinum natans.
Identification: Genus Crinum — Crinum.
Hydrocotyle leucocephala, sibthorpioides, verticillata, vulgaris.
Alternanthera reineckii lilacina, rosaefolia, Alternanthera sessilis. 
