Propagation by runners, offshoots, and stolons.
Propagation via lateral stolons is one of the most common methods of multiplying aquatic plants. Among aquarium flora, plants from a wide variety of families and with drastically different lifestyles propagate this way. Some plants have adapted to live in the water column, such as Vallisneria spiralis, others float on the surface like Salvinia auriculata, while others grow in semi-submerged or open substrate. This includes most plant species belonging to the families Alismataceae and Araceae. This is typical for Vallisneria, Echinodorus tenellus, and Eleocharis. The stems of many aquarium plants – Cryptocoryne, Anubias, Lagenandra, and some Echinodorus – take the form of a creeping rhizome. Shoot growth occurs at varying speeds depending on the species.
An offset is a young plant formed on a creeping shoot. Propagation by offsets, which arise on more or less long creeping shoots of strong parent plants, is of great importance in aquarium keeping. In some plants, such as Vallisneria, the creeping shoot formed in the leaf axil consists of a long internode with a bud at the end and is called a runner. First, the internode grows horizontally, and then development shifts to the bud, which forms the roots and leaves of the young plant – the offset. It in turn produces runners, and the formation of new offsets follows one after another, forming a “chain” of plants.
An offset that has formed leaves and roots begins to feed independently, and it can be separated from the parent plant, but this will slow down the formation of the next offset. Offshoots should only be separated from the parent plant when they have formed a sufficient root system. If the runners are not cut, optimal plant propagation can be achieved. Over time, the runners connecting the plants die off. While Cryptocoryne development should be interfered with as little as possible, species like Echinodorus and Sagittaria require regular thinning of overcrowded populations and newly planted offsets.
Plants that appear as creeping rhizomes (Cryptocoryne, Anubias, Lagenandra, and some Echinodorus) develop relatively slowly and form any noticeable rhizome in about a year. Young plants develop from growth points on the rhizome. One must wait until the daughter plant forms an independent root system and several leaves. Offsets arise on the rhizome, which are usually located within the substrate layer. The main shoot forms at the terminal point of the offset. In some species, after the development or separation of the main shoot, new daughter plants form on the offset.
Many Echinodorus species reproduce vegetatively by forming substrate runners with numerous young plants. This propagation process is very characteristic of Echinodorus tenellus and narrow-leaved swords. Young plants can be safely separated from the parent bush after they have formed roots. Separating a runner before a fully formed plant develops on it is premature. Echinodorus species that easily propagate via runners can quickly overrun the entire aquarium.
In other plants, such as Cryptocoryne, the creeping shoot consists of several internodes and is called a whip. A single basal leaf sits at the node, and adventitious roots are formed. The whip develops under the substrate for some time, then the tip breaks through the surface, creating a compressed internode that can be considered a rhizome. With its appearance, intensive root formation begins, and the basal leaves are replaced by normal ones – a young plant (offset) is formed, which can be separated after 2-3 leaves have developed.
New whips usually form from a section of the rhizome, but can also arise from buds in the axils of basal leaves. However, keep in mind that offsets should not be separated from the parent plant too early, as they will grow too slowly or stop growing altogether. The young plant should grow to a third, preferably half, the size of the parent (in Cryptocoryne, they are almost the same size).
Barclaya longifolia can also be propagated this way by periodically dividing the dense thickets that form. It should be noted that these plants start growing very slowly. A much better result can be achieved by not cutting the rhizome, but waiting until the daughter plants formed on the parent rhizome develop an independent root system.
Such a young plant can be separated from the main rhizome quite easily and planted in the substrate. Well-developed young plants quickly adapt to their new location and begin to grow. Meanwhile, new side shoots very quickly form on the parent plant’s rhizome. Propagation by separating daughter plants is more productive than propagation by cutting the rhizome.
Cryptocorynes propagate very well through root suckers. In this case, a shoot appears among the roots, extending far under the substrate from the parent plant. At some point, a bud awakens at its tip, growing to the surface with young leaves. As a result, they form thickets that should be periodically thinned by removing some of the newly formed bushes to allow the remaining plants to develop fully.
Once the new plant gains strength, it can be pinched off from the parent. Very small plants accidentally pulled from the substrate are best not transplanted into a new aquarium, but planted back in their original spot. This helps preserve even very small and weak plants. After a certain period, old plants can be removed and replaced with new ones to prevent the planting from “aging”.
Many floating plant species, such as Hydrocharis, Limnobium, Pistia, and others, also reproduce via offsets. The offset of a floating plant is not separated manually; the connection breaks down on its own.
Let us look at the propagation of Cryptocoryne blassii as an example. A small plant planted in an aquarium begins to grow under favorable conditions and can reproduce as its root system, stem, and leaves develop. The plant has a short, thick, fleshy stem on which leaf buds appear. New stems begin to develop from these buds, bearing adventitious roots along their entire length and leaf buds at the ends. Young plantlets develop from these buds. Initially, they remain attached to the parent plant, then the stems connecting them to the parent plant rot away, and the young plants become independent.
As a result, they form thickets that should be periodically thinned by removing some of the newly formed bushes to allow the remaining plants to develop fully. Very small plants accidentally pulled from the substrate are best replanted in their old spot rather than a new aquarium. This ensures even very small and weak plants are saved. Barclaya longifolia can also be propagated using this method by periodically dividing the dense thickets.
Daughter plants of Cryptocoryne species – Cryptocoryne blassii, Cr. balansae, Cr. spiralis, etc. – grow at a considerable distance from the parent plant; in other species, such as Cryptocoryne beckettii, Cr. lutea, Cr. minima, etc., they grow in close proximity and form distinct groups. A plant of this genus, propagating via substrate runners, can produce 8–10 new plants per year. Young plant specimens aged 1–3 years produce more plantlets than the same plants aged 3 years and older.
Plants belonging to the genus Echinodorus grown in the water column 
reproduce using runners with leaf buds (flower stems). For example, Echinodorus amazonicus produces a runner with numerous leaf buds as foliage develops. A rosette with leaves and later roots develops from each bud. If the flower stalk remains under water, a young plant soon appears at each node. As the leaves and roots of the rosettes develop, the runner becomes heavier and sinks to the bottom, where they can be separated from the stalk and planted in the substrate.
You can bend the flower stalk to the substrate, weigh it down with a stone, and allow the young plants to root; daughter plants develop very quickly. On a stalk not pinned to the substrate, side shoots develop much slower. Once rooted, the plantlets begin to grow rapidly and become independent within a few months. Such rosettes with leaves and roots can form on flower stems even when they do not rise above the water surface (in Echinodorus major).
Young plants can be safely separated from the parent bush after they have formed roots. Separating a runner before a fully formed plant grows on it is premature. Some plants with shortened stems develop a flower stalk ending in an inflorescence. In several Echinodorus species, daughter plants form around the inflorescence, usually growing underwater. After forming roots and 5-7 leaves, they are separated and planted in the substrate. You can bend the flower stalk to the substrate and weigh it down with a stone so the daughter plants take root. Some Aponogeton species also form a daughter plant near the inflorescence, which is separated after a tuber and several leaves have formed.
It should be noted that when daughter plants form on flower stalks, some Echinodorus species significantly slow their growth, become smaller, and lose their decorative appeal for two to three months. This trait is clearly expressed in Echinodorus osiris, Echinodorus major, and Echinodorus horemanii. It is less noticeable in Echinodorus sellowianus, Echinodorus verticillatus, Echinodorus aschersonianus, and some others when kept in an aquarium. By trimming the flower spikes, the decorative qualities of these interesting plants can be preserved.
After daughter plants form on the flower spike, even before their root system develops, the entire flower stalk can be cut off and placed in a separate tray, pinned to the substrate with pins. Such a stalk should be placed under strong light at a shallow depth. Daughter plants develop very slowly, but this method preserves the decorative qualities of the parent bush while yielding new plants.
