Hi all,
So is a flowering plant in good health or is that too general? In terrestrial plants flowering would normally be associated with the plant being well looked after and in good health.
I think generally this is the same for most aquatics/emergents.
I think a lot of it it do with what types of plant, all plants aren't going to flower under water (even
Vallisneria has male flowers which float after they have been released) as pollen and water isn't a good mix.
If you let plants like
Hygrophila corymbosa, Heteranthera zosterifolia, Cabomba spp. or Utricularia gibba grow in a tangled mass at the water surface they will then send up aerial stems that will flower. In
Cabomba , the leaf morphology will change to form small "pads" before flowering is initiated.
The same applies to
Cryptocoryne and
Echinodorus spp., if you have large healthy submerged plants, and then drop the water level, this will initiate flower production. You can also do this with
Nymphaea spp., allow them to form floating pads and they will flower. If you have a look at "Ghostsword" or "Schruz's" emersed threads, you will see a lot of aquatics are really emergent or totally terrestrial marsh plants and flowering is only suppressed by being submerged.
For a lot of perennial plants, they will grow vegetatively all the time resources are available, and in
Echinodorus if the plant is ready to flower and still submerged the flowering scape will have "plantlets", rather than flowers. A lot of other plants do this. I've got an orchid,
Dendrobium kingianum, in which you can manipulate flower or pseudobulb ("keiki") production by changing the watering regime. The last variable is light, a lot of plants will flower if you expose them to higher light levels.
Limnobium laevigatum is a really good example of this, natural day-light levels of light = flowers.
Annual plants are slightly different, they are programmed to flower, and flower production is usually triggered by lack of resources. These plants only way of reproduction is seed formation, and in really nutrient starved conditions minute plants will flower and die, producing only one or two seeds. In more nutrient rich conditions a genetically similar plant may be capable of producing 10,000's of seeds. Have a look at "Rapid Cycling Brassica" for details. I can't think of any obligate annuals as aquarium plants, but there may be some.
cheers Darrel