Aquatic Crinums

[CG100]

I asked for some advice about a year ago, about aquatic Crinums. Thanks for the conversations that resulted.
As I bought some bulbs, I thought that I would provide some feedback.
I bought two small bulbs of both C. thaianum and C. natans from aquarium supply outlets, mostly because they were the cheapest and the whole thing would be an experiment.
They were potted into 3 inch porous clay pots using a very gritty/sandy compost, and then the pots were put into 1 litre plastic laboratory beakers (also very cheap), sitting on a shallow layer of large pebbles. The beakers were then filled with rain water so that the bulb necks were clear of the water, and placed on indoor window sills. They were/are fed totally randomly by adding fertiliser (Miracle-Gro) to the top-up water.
All bulbs grew well in 2021, making good leaf growth. During last winter they probably routinely saw lows of around 10C, maybe slightly lower. C. t. lost all leaf although C. n. just stopped growth. I let the water drop so that just the base of the clay pots remained wet.
Once the plants showed the beginning of growth this spring, 2022, the beakers were filled again.
C. thaianum each have 4 very deep green, glossy and very lax leaves 12-15 inches long that lie "in a heap" beside the beakers, so do not touch water.
C. natans isn't C. natans!!
For some reason it did not occur to me until this spring, but the leaves are narrow and the edges are not puckered. The leaf growths are rather like a spider plant (Chlorophytum comosum). It is anyone's guess where the plants originated from, but Crinum sp. or not, it will be very interesting to discover the species – all I have to do is flower at least one of them!!!!!!
The supposed C. natans came with European labels and if sourced from NL, may be wild-collected, as the country is well-known for some level of below the radar trading in lots of plant species.
One of the unknown Crinums has made two small offsets, although one is dormant, but still firm. It may be the aspect of the window sill – unshaded, west-facing – but both are a less deep green than I would like, so they have been moved to an unshaded position on a north-facing sill.
The C. thaianum are on a south-facing sill in dappled light as a consequence of outdoor trees and shrubs casting diffuse shadows.
Another challenge will be deciding if and when they need repotting and then finding some acceptable and suitably sized outer water-tight vessels.

[Uli]

Hello CG100, 
Sorry to call you by this name but I do not see any other.

Your statements are very interesting. Mainly because I would have thought that both species of Crinum grow entirely submerged. The habitat pictures show exactly that. But they are obviously very adaptive plants.
I do not think that the unknown species is wild collected. Aquatic Crinum are very popular aquarium plants in Europe and raised in large numbers from seed. The seed might be wild collected but it probably comes from aquatic nurseries in Thailand.
A mix up of species is always possible but may the different look of the plant be related to its growing conditions?
I would not be faint hearted when it comes to potting up but better in spring.

Bye for now 

Uli 

[CG100]

Hi Uli

My moniker is Carl.
I have only seen the names natans, thaianum and calamistratum used for aquarium Crinums in the UK. The "not natans" plants are like none of them. They may not even be Crinums as the leaves only grow to 15cm or so and then die completely - if they survive, I would assume that the leaves will increase in size, but Crinum leaves are usually extremely long and survive over several years, even if dying back from the tip, though not sp. such as paludosum.

NL is notorious for handling "strange" plant material - there is a large and interesting article online about trully vast numbers of wild-collected Galanthus being laundered as nursery-raised.

If you search hard, you will find pictures online of wild "aquatic" Crinums growing in shallow water and at the water's edge. I am sure bulbs must get washed out by floods and eventually come to rest on the shore.  Plus there are the spp. that the S Africans call vleileli - the Crinum species (the name is also applied to some Nerine spp.) that only appear above ground and flower if there is a few inches of water lying, as a result of seasonal rains - spp like paludosum. (I tried a single bulb of campanulatum - another vleileli that is grown as a pond plant in warmer parts of the world, grown the same way - it rotted.)
Certainly, so far, thaianum here does not need to be completely submerged, or the leaves to be wet.

[CG100]

Quick update - coincidence or not, the "not natans" look far happier on the north-facing sill, and are already a better and more uniform shade of green.

[CG100]

The latest - all are still growing well enough - longest leaves on thianum are around 2 feet/60cm. Presumably because they are better established than a year ago, none show signs of dying-back as days have shortened.
The thianum will have seen temperatures down to 12-15C, the not-natans a bit lower.

I did repot one not-natans and found that all the roots, pretty much, were in the top of the pot, even though the clay pot that it is submerged in should keep all the compost aerobic. It put on a nice spurt of growth after repotting into a 5 inch/120mm pot.

The pic's tend to be of freshly imported, usually wild-collected, bulbs, but there are reasonable numbers of pic's online, of bulbs in bud/flower and bulbs appear to be no great size - 2 inches at the very most.