Subclass Alismatidae
Order Alismatales
Family Aponogetonaceae
Genus Aponogeton.
Species with tubers and rhizomes are distinguished. The rhizomes are tuberous, ranging from spherical, cream-colored in young plants, to brown, the size of a child’s fist, covered with dark brown remains of old roots. There is usually a single growth point, but exceptions occur: A. ulvaceus often forms multiple growth points, which allows the rhizomes to be divided. In the aquarium, rhizomes can be damaged by algae-scraping fish (Ancistrus, some Cichlidae), so they must be planted deep into the substrate.
When purchasing a plant, attention should be paid to its tuber, which should be firm, free of rotting areas and unpleasant odors. It should not be pressed into the substrate; it is enough to simply secure the tuber between stones, and the growing roots will pull it into the substrate themselves. If the tuber does not root for a long time and begins to rot, the rotting parts must be cut off down to healthy tissue and the cut area rubbed with charcoal powder. Then the cut should be dried, avoiding drying out the leaf growth point.
Aponogetons have submerged and floating leaves. The stem in all representatives of the genus is short. Leaves are on more or less long petioles of various shapes. The length of petioles in aquariums depends on lighting: with insufficient light, petioles elongate, while bright lighting presses the plants to the substrate, and leaves on short petioles form a horizontal rosette. Some leaves are narrow, ribbon-like, with a pointed tip, others are wide, ovate, on a relatively short petiole, but most often lanceolate, oblong. Leaves are gathered in a rosette.
Leaves are extremely delicate and resistant to mechanical impact, and many of them have specific demands on water composition and light intensity. The length of some oblong leaves reaches 40-50 cm with a width of 3-4 cm. Leaf color varies from light green to crimson in young ones, dark brown, and cherry in some species and varieties. Leaves are mostly submerged, sometimes near-surface, non-emergent (most species inhabit flowing water, with leaves located near the surface in the water current), but a number of species also form floating, emergent leaves.
In cultivation, Aponogetons are divided into four groups: — those that develop in aquariums without problems, — those that adapt with difficulty in indoor water bodies, — those that completely fail to survive in captivity, and — finally, those not yet imported alive, and therefore nothing can be said about their cultivation yet. The first group of species can be grown by planting in a pure sand substrate, while the second group is best planted in pots, filled with pure sand as well. The substrate sand should be periodically loosened, washed, and replanting from pots into clean sand is best done twice a year.
They can grow at a steady rhythm, or suddenly activate growth for several months and look magnificent, after which leaf growth stops and the plant may die. Similarly, old leaves of Aponogeton may begin to die off. In nature, many Aponogeton species have a dormancy period during which some species drop their leaves, while others stop growing and do not produce new leaves. This period can last for months. If the water parameters in the aquarium are suitable for this plant, new, fresh leaves will immediately start growing after the old ones die off.
After the rest period ends, the plant often refuses to wake up, although the tuber is clearly viable. During the dormancy period, rhizomes resting in the substrate without leaves can be lost; sometimes they die, ending up amidst the rot of dead roots. A plant entering dormancy (leaves appear less and less frequently, become smaller, and finally growth stops completely) is best dug up in time and placed in a container with sterile sand and a water temperature of 15-20°C.
When the rested rhizomes sprout young leaves again, they are moved to the aquarium at a pre-planned location. It is recommended to replant young plants more often so they develop better. If you notice in your aquarium that the leaves have not grown for quite a while, replant the plant to another part of the aquarium; then the dormancy period should end, and the plant should resume growth. When you have a bulb from which you want to grow an Aponogeton, you simply need to place it in a container with wet, cold sand and leave it in a cool, dark place for 6 weeks. It should only be placed in the aquarium when young leaves begin to grow from the bulb.
Under favorable conditions, Aponogetons represent the fastest-growing group of short-stemmed plants in the aquarium. Plants 15 cm in height are planted. When planting young shoots, keep in mind that for several days, and in some cases 2-3 weeks, rapid growth should not be expected, as the plant will first shed all its roots through decay, and only then will new roots begin to grow. Although in natural conditions, in nutrient-rich soils, the root system of Aponogetons is essential for nutrient storage, in the aquarium, well-lit, freely positioned leaves play the main role in plant nutrition.
A common mistake of beginner aquarists is that Aponogetons love fresh water very much. Constant replacement of fresh water is necessary. In still aquarium water, these plants often experience carbon starvation. For most Aponogetons, the most acceptable temperature is 22-25°C, but Aponogeton madagascariensis (Uvirandra) also grows at 16-20°C.
The water should preferably be soft; easy-to-culture species tolerate hardness up to 20°, problematic ones up to 10-12°, and lattice-leaved ones grow at hardness no greater than 5-6°. The optimal active reaction of water for Aponogetons is neutral, with a slight shift toward the acidic side at pH 7-6.3. The redox potential is high — 30-28. In an aquarium with old, long-unchanged water and heavily silted substrate, growth stops, followed by leaf destruction and plant death.
Water flow is mandatory, achieved by changing 10% of the water weekly. Water movement, achieved using aeration and filters, is necessary; the leaves of these plants in nature are constantly washed by currents and suffer when dirt and mucus accumulate on them. Keeping plants from Madagascar is very difficult and requires experience. Plants with a net-like leaf structure are extremely difficult to maintain; they need clean, transparent water with dH 1-4° and pH 7.0. They cannot tolerate humus-rich substrates, which cause the rhizome to rot. They are very prone to algal overgrowth.
Australian Aponogetons.
Aponogeton elongatus.
«1» Australia. Standing and flowing waters, found in both sunny and shady places. This is a large plant with long, slightly wavy bright green leaves that can reach over 50 cm in length. Adult specimens develop up to 50 leaves. Petiolate leaves, ribbon-like, elongated-lanceolate in shape; lanceolate leaves taper toward the end, with some forms having a pointed tip and others rounded, soft, edges slightly wavy, length varying from 2.5 to 45 cm with a width of 0.5-5 cm. The leaf is light green, as well as yellow-green to reddish-brown. Leaves grow both submerged and semi-floating. Under less intense lighting, leaf petioles elongate, and the plant acquires elongated forms and loses its appeal; due to the tenderness and fragility of the leaves, its widespread cultivation is difficult.
The species has several forms, which, unlike the forms of previous Aponogetons, have received scientific names:
— Aponogeton elongatus f. elongates — Aponogeton elongatus with elongated leaves 15-30 cm long and 1.2-2.5 cm wide with wavy edges. Petiole 4-15 cm long, shorter than the leaf blade;
— Aponogeton elongatus f. latifolus — Broad-leaved Aponogeton with wide (up to 5 cm) leaves up to 40 cm long. Petiole length from 10 to 25 cm, but can be up to 45 cm;
— Aponogeton elongatus f. longifolius — Long-leaved Aponogeton with very long (up to 55 cm) narrow (2.5 cm) leaves, petiole length 50 cm;
— Aponogeton elongatus f. strigosus — Bristly Aponogeton with leaves up to 40 cm long, up to 5 cm wide. The smaller the water layer, the smaller the leaves. Tuber covered with spines.
«2» Best kept in a tropical aquarium with a water temperature from 24 to 26°C. Lowering the water temperature leads to slowed growth and then cessation. High water temperature (above 26°C) during the dormancy period exhausts the plant. Soft water with a total hardness of 2-6° is most suitable, but hardness up to 12° is also acceptable. The active water reaction should be close to neutral (pH 6.5-7.5). The plant loves fresh water, so it should be regularly changed. Aponogeton elongatus requires bright lighting — about 0.4 W per liter of aquarium volume. An indicator that Aponogeton has enough light is the reddish-brown color of young leaves. Daylight is about 12 hours.
«4» The root system of the plant is strongly developed, with a heavily branched root bunch. The rhizome is tuberous, up to 2.5 cm thick, rarely with spines around the growth point. Large and medium gravel can serve as a substrate. The substrate should be silted, with a large amount of organic matter. Clay or a mixture of clay and peat should be added under the plant’s roots in new substrate. In summer and autumn, during the period of vigorous Aponogeton growth, it is advisable to feed it with complex mineral fertilizers dominated by nitrogen. The substrate layer thickness in the aquarium should be about 7 cm.
«5» A very beautiful and fairly large aquatic plant with long, bright green, slightly wavy leaves. Suitable for keeping in a large body of water. Acts as a solitary specimen. Growth seasonality is weakly expressed; growth slows down in winter and spring, but most of the leaves remain. The aquarium’s fish stocking density should be low.
«6» At the end of the dormancy period, the oval rhizome of Aponogeton can be divided into 2-4 parts, ensuring growth buds are preserved on each. Rhizome pieces are best planted in a lightly silted substrate mixed with charcoal. A new plant develops from each rhizome piece. After 3-4 leaves have formed, the plant can be transplanted into the main aquarium.
Aponogeton bullosus.
Australia and Madagascar, in fast-flowing rivers, waterfalls fed by mountain streams with rather cold water. The rhizome is tuberous, elongated, thin, 1-2 cm thick, sometimes growing into sand between rocks. Leaves are submerged, their blade ribbon-like, usually 7-30, occasionally 50 cm long and 1-2 cm wide, puckered, dark green or brownish-green, young leaves reddish, narrowing toward the base and smoothly transitioning into the petiole, also smoothly narrowing toward the apex and ending in a bluntly oval tip. Venation is parallel, the main vein is thick, with up to 5 longitudinal veins. Petioles are very short, up to 10, rarely 15 cm in length.
When kept in an aquarium, it requires a water temperature of 25°C in summer and 16-18°C in winter, moderate lighting, and grows better with partial water changes. Solitary plant. Planted in nutrient-rich substrate. Propagated by seeds and tuber division. Water: 24-28°C, pH 6.5-7.5.
Aponogeton queenslandicus.
Australia. The plant has a spherical or oval rhizome up to 2.5 cm thick, spiny, with scars from fallen leaves. During development, the leaf shape changes. The first leaves 
appearing underwater are lanceolate, up to 20 cm long and 3.5 cm across, their base is oval, sometimes with a shallow heart-shaped notch; they are narrowed toward the apex, obtusely pointed. Venation is parallel, the main vein protrudes from below, usually up to 7, rarely up to 5 or 9 veins are visible, petioles up to 10 cm long. The main leaves are floating, light green, narrow-oval, 5-11 cm long and 0.8-3 cm across.
In aquarium conditions, the plant grows well at 26-28°C and pH 6.8-7.2. Substrate — coarse sand or fine river gravel mixed with fine peat crumbs and humus-rich clay. It grows better in clean, fresh water with good lighting and intensive water aeration by a compressor or water pump. The plant reproduces by separating daughter plantlets after at least 3-4 leaves have developed on the mother plant. Young plantlets must be separated very carefully so as not to harm the parent plant.
Aponogeton crispus, Aponogeton undulatus.
Lilaeopsis brasiliensis, carolinensis, macloviana, mauritiana. 
