Subclass Alismatidae
Order Alismatales
Family Aponogetonaceae
Continued…
Genus Aponogeton.
Asian and Indonesian species.
Aponogeton rigidifolius.
“1” Island of Sri Lanka. The plant has a branched, long rhizome up to 1 cm in diameter and a shortened stem with a rosette of petiolate leaves. The height of the bush in the aquarium reaches 45-60 cm and a width of 25-35 cm, forming a dense rosette of dark green or brownish corrugated leaves on a shortened stem. But even under favorable conditions, it grows slowly. It forms long narrow leaves up to 50 cm, up to 3 cm wide, slightly wavy at the edges, with a pointed apex. Depending on water hardness and lighting, the leaves can be of various density and coloration: from crimson-brown young and dark green with a brown tint in old ones to dark green without signs of brown color, turning brownish-brown under intense lighting. On the sides of the main vein, there are 3-4 pairs of parallel veins.
Growth is extremely slow. Under the influence of light, the leaves perform daily movements, lowering at night, straightening during the day, and vice versa in bright sunlight. Does not need a dormant period. Unlike most other varieties, it does not have a developed root system, attaching with rhizoids. When purchasing, you should pay attention that the plant is at least 10 cm in size.
Selected forms have been bred:
— “Red” – Leaf blade 3-6 cm wide, initially red or pink, then green or golden.
— “Leder” – Leathery Aponogeton. Leaf blade 3-6 cm wide, light green or golden. This hybrid under any conditions does not show red-brown coloration.
— “Chocolate” – Leaf length 15-25 cm. Leaf blade 1-1.5 cm wide with a pointed apex, red to dark brown in color. With red-brown petioles and the presence of a brown tint on wide, slightly wavy, rounded-tipped leaves.
“2” Water temperature 22-28°C. At temperatures below 22°C, growth almost stops. Aponogeton rigidifolius is one of the few species that needs harder water than its other relatives. Water with a hardness of 7 to 12° is most suitable for it, which must be taken into account when keeping it with fish. The active reaction should be neutral or slightly alkaline pH 6.0-8.0. The plant belongs to demanding and light-loving species. Lighting should be of medium intensity, about 0.4 W/l. The preferred daylight duration is at least 12 hours. If the plant dislikes something, its leaves become covered with spots and eventually fall off.
“4” The rhizome of this Aponogeton is fundamentally different from the species described above and is found only in one variety of Aponogeton madagascariensis – it is creeping, about 1 cm in diameter and up to 15 cm long. The soil should be moderately silted. It is advisable to add clay, peat, and charcoal to the soil. A wide variety of soil substrates can be used, but fine or medium gravel is preferred, which should be laid in a layer of at least 5 cm, since the plant forms a sufficiently developed root system.
This species of Aponogeton grows slower than other representatives of the genus, so when mineral nutrients are lacking in the water, signs of mineral starvation appear in it later than in other species. Rather capricious, requires complex care, including control of soil nutrient saturation, additional carbon dioxide supply, regular root and foliar feeding. By constantly feeding the plant with minimal doses of complex mineral fertilizers, its stable growth can be achieved.
“5” The aquarium should be spacious, with a high water level. It is a solitaire plant, best planted separately from all plants (the chocolate form is planted in a group in the middle ground). The plant should be placed in the background, in corners or near the side walls of the aquarium. Constant water circulation is very essential for maintenance, so the optimal location is near the filter. When care mistakes are made, the leaves become covered with spots and wither.
Although the species develops slowly in the aquarium, within a few months it grows into a luxurious plant. If natural light enters the aquarium, the color of the plant’s leaves is much brighter than under artificial lighting alone. The plant does not need a dormant period. During the growth period, an adult Aponogeton rigidifolius produces about 1 leaf per month. It tolerates transplantation poorly.
“6” It is usually propagated vegetatively. It reproduces either by offsets on the rhizome appearing near the mother plant, or forcibly by dividing the rhizome. The long rhizome formed in this species of Aponogeton is cut into pieces. Each part of the rhizome should have at least two growth buds, from which a new plant subsequently develops. On the old rhizome, if left undisturbed, young plants form, which after the formation of 3-4 leaves can be separated and replanted in a new place.
Aponogeton robinsonii.
Synonym: Aponogeton eberhardtii. Inhabits Central and Southern Vietnam. Leaf blade with a petiole up to 60 cm, ribbon-like, transparent, 30-40 cm long, up to 3.5 cm wide, olive to olive-green, young leaves can be brown. The edges of the blade are slightly wavy. The end of the leaf is pointed or acutely rounded, the central vein is wide, with two longitudinal veins on each side. It has dense, rigid, and slightly oily to the touch leaves. Located vertically in the water on short petioles. Its leaves do not float, but are located under the water surface. Bush width up to 35 cm. After several months in favorable conditions, it can develop into a large, very attractive plant with beautiful, dark green riffled leaves.
Unlike most other varieties, it does not have a developed root system, is attached by rhizoids, and does not require a dormant period. Undemanding to water quality, thrives in both hard and soft water, and is content with moderate lighting. Can grow in the aquarium for several years. The rhizome is tuberous, rounded, small, up to 2 cm thick. The soil should be nutritious and loose. Strong water circulation promotes the development of strong plants.
Requires fairly spacious bodies of water with a high water level, as it reaches 60 cm in height. Planted in the middle and background. To make the most of the decorative impression of the plant, aquariums of at least 50 cm in height are recommended. dH up to 15; pH up to 15; T 25-27°C.
Aponogeton madagascariensis, Aponogeton ulvaceus.
Aponogeton crispus, Aponogeton undulatus. 
