Flowering Rosette Plants in the AquariumAuthor: Rhonda Wilson
Most of the plants we grow in our aquariums flower naturally in the wild, but this can be a rare instance in home aquaria. It can be very exciting to find your aquatic plants producing blossoms, and some can even be propagated this way. There are a few tips for knowing what plants are most likely to flower, and what they need in order to do so.
All flowering plants are called angiosperms. Not all the plants in the aquarium are angiosperms. Mosses, liverworts like Riccia and pelia, and aquatic ferns like Java fern, Bolbitis, and Ceratopteris,are more primitive plants that don’t produce flowers or seeds, but instead create spores, thus their name of “sporophytes.”
Of course any of the flowering plants that we keep in our aquariums have the potential to flower for us, but some are much more likely to do so than others. There are several aquarium plants that are happy to surprise us with flowers, while others may require more coaxing. In this column and the next I’ll list a few of the aquatic plants most likely to bloom in the aquarium, as well as the type of care they need in order for this to happen.
For many people, one of the first aquatic plants to bloom in the aquarium is Aponogeton crispus, which has been popular in the hobby for many years. This species is quite variable and can be crossed with other Aponogeton, which has resulted in several established cultivars as well as hybrid plants. One of the reasons that Aponogeton has become so popular in the aquarium trade is the ability of the rhizome to withstand a dry period, making these plants easy to ship. You may even see them hanging in small dry bags in pet sections of larger stores.
I’ve personally had some problems with the bagged rhizomes surviving, but I have had success with the ones I purchased already sprouting in aquarium stores. The problems I’ve had with the bagged type were probably due to me living in the hot, dry Arizona desert. It seems reasonable that they would easily dry out or get too hot during shipping here. I’ve heard of many other success stories with the dry Aponogeton rhizomes in other parts of the country, though.
These plants will usually do better in soft to moderate water and may have troubles in harder water. They will appreciate a rich substrate. In a new aquarium or a tank with very clean substrate and no additional nutrients, Aponogeton will probably only last for a few months at best. It will do better with specially prepared aquarium plant substrates, or if you’d rather, you can use a small layer of potting soil or compost under your gravel. There are many options available and most of them seem to do the job if you’re consistent in your approach. The addition of CO2 can also be helpful for growing Aponogeton, particularly if you have harder water. The plants may sometimes die down and may not seem to have the longevity of some aquarium plants, but many can be kept alive for several years if they are well cared for.
When your Aponogeton flowers, you may observe the slim stalk coming up between the leaves, though if you’re not looking for it, you might not notice. When it breaks the surface of the water you’ll probably see it. Initially the flower spike, called an inflorescence, is covered by a green spathe, but soon the spike will pop out, covered with white or violet-tinted flowers. In A. crispus there is one flower spike, but depending on the species, Aponogeton can have two to three violet or purple flowers. Sometimes seeds can be produced from the flowers. The pollen must be carefully transferred between the flowers with a small brush or cotton swab. If your plant is self-pollinating then green “berries” will develop and drop into the water. These will float until they open and drop the seed to the bottom of the aquarium, where they can grow into new plants. Fish and other aquarium inhabitants may snack on your seeds. Removing the fish or the seeds to another tank will increase your chance of getting baby plants.
The swordplants Echinodorus spp. are other favorites that bloom readily in the aquarium. In fact you can often buy large Amazon “mother” swords with many baby swords. These are called adventitious plants and they can sometimes develop while the plant is blooming. Like the Aponogeton plants, swords can be hybridized and cultivated.
I’ve had several swordplants bloom for me. Separately, I’ve noticed that some of these plants turn brown and die as soon as any part rises above the water. This is probably once again due to the extremely dry conditions in Arizona. Covering your tank can prevent dryness in plants that grow above the water surface and this is generally recommended. I do have other swords that seem to be a bit better suited to surviving in more arid climates, which will bloom happily and with some regularity. I have one group in my living room that’s been blooming regularly for years, producing many adventitious babies that have found places to live in other aquariums both in my home and in the homes of others.
Swordplants require a good healthy substrate to perform at their best. In addition to the prepared mixes, or adding special substrates or potting soil, I’ve also kept very nice swords using compressed peat plates under the gravel. Most swords for the aquarium that are found for sale are very easy to care for in terms of lighting, water pH, and hardness. I’ve had quite a lot of luck growing swords in my hard, alkaline Arizona water, with everything from strong fluorescent lighting to filtered sunlight.
Swords normally have moderate growth speeds, but with the addition of CO2 they can grow much faster. Most of them can also get quite large and should be placed in an appropriately sized aquarium. A moderate-size sword can easily fill most of a 20-gallon aquarium, and a very large sword will have no problem filling 50 gallons.
When your swordplant flowers, it will generally send an inflorescence up out of the surface of your tank. If you have an open tank, be sure to keep it from getting into the light where it will be burned. Some swordplants can have a branching inflorescence. I’ve noticed that even when a plant doesn’t generally branch, it may if it is damaged in some way during growth, like getting into the aforementioned aquarium lights. Blossoms from these inflorescences develop into small white flowers.
Your swordplants can produce seeds, but this can be a somewhat difficult process; fortunately they will often produce adventitious plantlets, or baby plants. I’ve read that these are more often encouraged if the inflorescence is kept underwater. They certainly don’t want to grow roots until placed back under the water, and it will be best if your plantlets get used to life below the water early on, since you’ll probably want to move them to another aquarium when they get larger. After the plants have grown several leaves and a good root system, they can be removed from the parent plant. I’ve found that the larger the plant is when removed (within reason), the better the chance it has of surviving—and the quicker it will become acclimated to its new life on its own.
Another plant that likes to surprise you with its blossoms is the moderately sized grassy Sagittaria subulata. Sometimes mistaken for Vallisneria, Sagittaria is usually smaller and (for me at least) grows at a much more reasonable pace than val, which can seemingly take over an entire aquarium overnight. In my experience, Sagittaria has been more likely to bloom in the home aquarium than val—and it does so regularly.
S. subulata is an undemanding plant. It usually stays at a medium height, making it nice for the mid-ground in smaller tanks or the foreground in larger ones. Sagittaria seem to do well in most tanks. I’ve had them grow wonderfully and bloom in aquariums with plain gravel and low light, and in the soupy nutrient-filled tubs I keep under shade cloth in the Arizona sun. They seem to be quite happy in either extreme. I’ve been surprised by blossoms in forgotten tanks in the corner of the fishroom.
When flowering, S. subulata sends a long stalk to the surface of the tank. Small, white, delicate flowers with three petals float at the surface of the water. Although they do seed in the wild, it’s not practical in the aquarium. Fortunately S. subulata reproduce quite well through runners, so even without seeds you should end up with plenty of extra plants.
Aquarium plant blooms aren’t as showy as those you can grow on your houseplants or out in your garden, but it is fun to experience this aspect of the hobby.
Next time I’ll discuss the stemmed plants and how you will have to do a little more planning if you want to see them bloom. Plus, I’ll take a look at some plants that show off their best blossoms in a high-tech tank.
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